Germination and stress tolerance of oats treated with pulsed electric field at different phases of seedling growth

This study explores the impact of pulsed electric field (PEF) application on oat seedling growth and stress tolerance. PEF treatment (99 monopolar, rectangular pulses lasting 10 µs each, with a frequency of 13 Hz and a nominal electric field strength of 2250 V/cm) was applied at two growth stages: (i) when the seedlings had 0.2 cm roots emerging from the kernel, and (ii) when they had a 0.4 cm shoot emerging from the kernel. Post-treatment, the seedlings were hydroponically grown for 8 days. To induce stress, the hydroponic medium was augmented with PEG (15 %) to induce drought stress and NaCl (150 mM) to induce salinity stress. Results demonstrate that applying PEF improved the growth of the root and shoot of oat seedlings. This effect was more pronounced when applied to more developed seedlings. When PEF was applied during the later stage of germination, seedlings exposed to salinity stress showed enhanced shoot growth compared to the control. Under the studied conditions, the application of PEF had no impact on the growth of seedlings under drought stress.

Physiological response and tolerance of Sesuvium portulacastrum L. to low temperature stress

The plant Sesuvium portulacastrum L., commonly referred to as sea purslane, is a perennial halophytic species with significant potential for development in marine ecological restoration. However, its growth is limited in high-latitude regions with lower temperatures due to its subtropical nature. Furthermore, literature on its cold tolerance is scarce. This study, therefore, focused on sea purslane plants naturally overwintering in Ningbo (29°77'N), investigating their morphological, histological, rooting, and physiological responses to low temperatures (7 °C, 11 °C, 15 °C, and 19 °C). The findings indicated an escalation in cold damage severity with decreasing temperatures. At 7 °C, the plants failed to root and subsequently perished. In contrast, at 11 °C, root systems developed, while at 15 °C and 19 °C, the plants exhibited robust growth, outperforming the 11 °C group in terms of leaf number and root length significantly (P < 0.05). Histological analyses showed a marked reduction in leaf thickness under cold stress (P < 0.05), with disorganized leaf structure observed in the 7 °C group, whereas it remained stable at higher temperatures. No root primordia were evident in the vascular cambium of the 7 and 11 °C groups, in contrast to the 15 and 19 °C groups. Total chlorophyll content decreased with temperature, following the order: 19 °C > 15 °C > 11 °C > 7 °C. Notably, ascorbic acid levels were significantly higher in the 7 and 11 °C groups than in the 15 and 19 °C groups. Additionally, the proline concentration in the 7 °C group was approximately fourfold higher than in the 19 °C group. Activities of antioxidant enzymes-superoxide dismutase, peroxidase, and catalase-were significantly elevated in the 7 and 11 °C groups compared to the 15 and 19 °C groups. Moreover, the malondialdehyde content in the 7 °C group (36.63 ± 1.75 nmol/g) was significantly higher, about 5.5 and 9.6 times, compared to the 15 °C and 19 °C groups, respectively. In summary, 7 °C is a critical threshold for sea purslane stem segments; below this temperature, cellular homeostasis is disrupted, leading to an excessive accumulation of lipid peroxides and subsequent death due to an inability to neutralize excess reactive oxygen species. At 11 °C, although photosynthesis is impaired, self-protective mechanisms such as enhanced antioxidative systems and osmoregulation are activated. However, root development is compromised, resulting in stunted growth. These results contribute to expanding the geographic distribution of sea purslane and provide a theoretical basis for its ecological restoration in high-latitude mariculture.

Supplementary Information

The online version contains supplementary material available at 10.1007/s12298-024-01429-6.

Direct Shoot From Root and True-to-Type Micropropagation of Limonium "Misty Blue" in Partially Immersed Culture on an Aluminum Mesh Raft

Commercial plant tissue culture now primarily serves the ornamental horticulture industry. The main pillars of the commercial tissue culture business are scalability of production, cost reduction, limited labor involvement, high quality, and genetic homogeneity of propagated plants. Based on these requirements, the current protocol employs a partially immersed liquid culture medium supported by a flexible aluminum mesh raft with a wire stand to facilitate shoot organogenesis from the horizontally placed root explants and hold the plants upright for shoot multiplication and rooting of Limonium Misty Blue. It is a florist crop that is in high demand as both dried and fresh flower fillers in various floral decorations. The majority of cultivated Limonium or statice cultivars are heterozygous in nature and propagate commercially through in vitro propagation to cater to the huge demand for planting materials needed for flower production. This is the first protocol to describe direct shoot organogenesis from the roots in a liquid half-component of Murashige and Skoog's (1962) (MS) basal medium supplemented with 1.6 μM NAA and 1.1 μM BA. The regenerated shoots are multiplied and rooted at the same time on the raft in a MS-based liquid culture medium that included 0.44 μM BA and 1.07 μM NAA. In comparison to agar-gelled medium, plants cultured in liquid medium grow more quickly without any signs of hyperhydricity. In liquid medium, a clump of 4-5 shoots is formed from a single shoot explant within 4 weeks and are rooted simultaneously within 6 weeks. On average, seven explants may fit on each raft, so on average, 25 healthy plants are produced from a single bottle. The regenerated plants are easily hardened in the greenhouse, and using ISSR-based molecular markers, the genetic homogeneity of the randomly selected hardened plants can be determined.

Aloe monticola Reynolds: A refugee of the mountains - contributing towards its conservation through in vitro propagation

In vitro micropropagation study of Aloe monticola Reynolds was conducted using offshoots in Murashige and Skoog (MS) media enriched with plant growth regulators (PGRs). Initiation experiment, carried out by culturing sterilized explants in full-strength MS media enriched with 0.0-1.0 mg/L benzyl amino purine (BAP) alone and in combination with 0.10 mg/L indole-3-butyric acid (IBA), resulted in 89 - 100 % healthy and live (i.e., initiated) explants in 9-29 days. Regeneration study, conducted by culturing initiated explants in full-strength MS media supplemented with 0.0-3.0 mg/L BAP alone and in combination with 0.50 mg/L IBA, showed that treatments enriched with 1.0-3.0 mg/L BAP in combination with 0.50 mg/L IBA yielded better shooting responses than the rest of the treatments. The rooting responses of the shoots were also tested by culturing in half-strength MS media enriched with 0.0-4.0 mg/L NAA alone and in combination with 0.25 mg/L IBA. Better rooting responses were observed in treatments supplemented with 1.0-4.0 mg/L NAA in combination with 0.25 mg/L IBA with two exceptions. The responses of A. monticola plantlets to primary and secondary acclimatization in greenhouse, nursery shade, and direct sunlight in coco peat, composted soil, and manured soil were excellent - with survival percentages of 90-98 %. The findings of this empirical research are important for developing refined protocol of in vitro micropropagation of this ecologically important but endangered plant.

In vitro and ex vitro propagation of Turkish myrtles through conventional and plantform bioreactor systems

The myrtle (Myrtus communis) plant naturally grows in the temperate Mediterranean and subtropical regions and is used for various purposes; thus, it is among the promising species of horticultural crops. This study aimed to evaluate and compare the performance of different propagation systems, including rooting, solid media propagation, rooting, and with the Plantform bioreactor system, in achieving healthy and rapid growth of four myrtle genotypes with diverse genetic origins and well-regional adaptation. The selection of myrtle genotypes with distinct genetic backgrounds and proven adaptability to specific regions allowed for a comprehensive assessment of the propagation systems under investigation. Present findings proved that the Plantform system, the new-generation tissue culture system, was quite successful in micropropagation and rooting myrtle genotypes. We succeeded in vitro micropropagation and rooting of diverse wild myrtle genotypes, enabling year-round propagation without reliance on specific seasons or environmental conditions. The process involved initiating cultures from explants and multiplying them through shoot proliferation in a controlled environment. This contributes to sustainable plant propagation, preserving and utilizing genetic resources for conservation and agriculture.

In vitro micropropagation of Aloe elegans Tod. using offshoot cuttings

OBJECTIVE

Aloe elegans Tod. is an ecologically, environmentally, medicinally, and commercially useful aloe species in Ethiopia and Eritrea. Unfortunately, it is highly threatened due to industrial and urban expansion and traditional mining and agricultural activities. As a consequence, it is included in the IUCN List of Threatened Species since 2013. The plant is getting thinly populated in many parts of the Tigrai floristic region since it is being exploited for traditional and commercial purposes. Therefore, this study was aimed to develop a reproducible, large-scale micropropagation protocol using offshoot cuttings in Murashige and Skoog (MS) media enriched with plant growth regulators (PGRs).

RESULTS

Sterilized explants cultured in full-strength MS media enriched with 0.25 mg/L benzyl amino purine (BAP) and 0.10 mg/L naphthaleneacetic acid (NAA) resulted in 100% healthy and live (i.e., initiated) explants after four weeks of initiation study. Unsupplemented initiation media (control) yielded only 14.3% initiated explants. The initiated explants were tested for their shooting response to produce microshoots by incubating in different concentrations and combinations of BAP and NAA for four weeks. Fewer days to shooting (13.0 ± 1.0 days), higher mean shoot number (5.0 ± 1.0), and higher mean shoot length (9.20 ± 2.35 cm) were observed with 1.0/0.50, 1.0/0.25, and 1.0 /0.50 mg/L BAP/NAA combinations, respectively. The rooting responses of the microshoots toward producing plantlets were also tested by incubating them in half-strength MS media enriched with different concentrations of NAA and indole-3-butyric acid (IBA) for four weeks. Fewer mean days to rooting (12.0 ± 1.0 days), higher mean root number (8.0 ± 4.0), and higher mean root length (7.53 ± 3.03 cm) were observed in MS media enriched with 0.75, 0.75, and 1.25 mg/L IBA, respectively. The responses of A. elegans plantlets to primary (in greenhouse) and secondary (in nursery shade and direct sunlight) acclimatization in coco peat, composted soil, and manured soil media were high - with survival percentages of 87.5-97.8% in three to four weeks.

Improvement of rooting and growth in kiwifruit (Actinidia deliciosa) cuttings with organic biostimulants

Seaweed extracts have shown profoundly positive effects on crop growth, quality and reproduction in diverse agricultural and horticultural crops. Seaweed extracts can be used to promote the rooting and growth of cuttings in perennial fruit species like kiwifruit (Actinidia deliciosa). In this study, the cuttings were treated with 1, 5, 10 and 50% solutions of G Sap (Gracilaria edulis), K Sap (Kappaphycus alvarezii), AN (Ascophyllum nodosum), EM (Ecklonia maxima), HA (Humic acid) and control (water) for 6 h as base dipping. Subsequently, the treatments of G Sap, K Sap, AN, EM, HA and control were repeated every 15 days for a period of six months as application of 50 ml solutions in the potted cuttings. All the treatments exhibited significant effects on the rooting percent in all the kiwifruit cultivars, namely 'Monty', 'Abott', 'Hayward', 'Allison' and 'Bruno' (P ≤ 0.01) as compared to the control. Shoot and root growth parameters including leaf number per cutting, number of roots per cutting, number of branches, plant height, shoot diameter, root length, root diameter and root weight were all positively increased with the application of seaweed extracts (P ≤ 0.05). Cuttings treated with seaweed extract exhibited significantly higher levels of pigments (chlorophyll a, chlorophyll b and total carotenoids), metabolites (total carbohydrates and soluble phenols) and less electrolyte leakage as compared to the control cuttings. Significant positive and negative correlations were observed between biochemical parameters combined with plant nutrient concentration. Principal component analysis (PCA) revealed that PC1 and PC2 (first two principal components) accounted for 75% of the entire variation. While, PC1 accounted for 63% of the total variation, PC2 accounted for 11% of the total variation. The leaves and the roots of kiwifruit cultivar 'Hayward' treated with G Sap at 10%, K Sap at 10%, AN at 10%, EM at 10%, HA at 10% exhibited higher expression of all four root promoting candidate genes (GH3-3, LBD16, LBD29 and LRP1) compared to the control. Therefore, it can be concluded that, seaweed extract and humic acid can be used as a suitable alternative to synthetic hormones for promoting the rooting and growth of kiwifruit cuttings.

Effect of sterilants and plant growth regulators in regenerating commonly used cassava cultivars at the Kenyan coast

Cassava is an important root crop whose seed system is undeveloped. Micropropagation of explants in vitro has the potential of addressing the challenge of the unavailability of healthy cassava planting materials. Therefore, the study determined the effect of sterilization and plant growth regulators on cassava explants to produce certified disease-free plants of commonly used cultivars at the coast of Kenya. The apical nodes drawn from the three cultivars of cassava, Tajirika and Kibandameno and Taita, were used as explants. The sterilant sodium hypochlorite (NaOCl) at 5, 10 and 15% and 70% ethanol for 1 and 5 min and sprayed for 20 s were tested for the effect on the explant. Similarly, the effect of BAP (6-Benzyl amino purine) and NAA (1-Naphthalene acetic acid) Plant Growth Regulators (PGRs) each at 0.5, 1 and 5 mg/L under optimal conditions of sterilization was determined. Surface sterilization using 10% NaOCl followed by spraying 70% ethanol for 20 s had 85% initiation on Tajirika whereas 5% NaOCl followed by spraying 70% ethanol for 20 s had 87% and 91% initiation in Kibandameno and Taita cultivars, respectively. In Tajirika, significantly (p < 0.05) high shooting of 68% was from 5 mg/L BAP in MS media whereas approximately 50% rooting was from either 0.5 mg/L BAP or 5 mg/L NAA in MS media. Kibandameno and Taita cultivars had approximately 50% shooting from MS media without PGRs. Kibandameno had >37% rooting from 0.5 to 5 mg/L BAP or NAA in MS media whereas Taita had approximately 50% rooting from 0 to 5 mg/L NAA in MS media. This protocol showed at least 50% success rate of initiation, shooting and rooting as a rapid multiplication regeneration of Tajirika and Kibandameno and Taita cultivar plantlets with little modification of humidity and temperatures in the growth chambers. This protocol requires validation for use in large-scale production of cassava plantlets to alleviate the inadequacy of cassava planting materials among farmers.

Phylogenomic Testing of Root Hypotheses

The determination of the last common ancestor (LCA) of a group of species plays a vital role in evolutionary theory. Traditionally, an LCA is inferred by the rooting of a fully resolved species tree. From a theoretical perspective, however, inference of the LCA amounts to the reconstruction of just one branch - the root branch - of the true species tree, and should therefore be a much easier task than the full resolution of the species tree. Discarding the reliance on a hypothesised species tree and its rooting leads us to re-evaluate what phylogenetic signal is directly relevant to LCA inference, and to recast the task as that of sampling the total evidence from all gene families at the genomic scope. Here we reformulate LCA and root inference in the framework of statistical hypothesis testing and outline an analytical procedure to formally test competing a-priori LCA hypotheses and to infer confidence sets for the earliest speciation events in the history of a group of species. Applying our methods to two demonstrative datasets we show that our inference of the opisthokonta LCA is well in agreement with the common knowledge. Inference of the proteobacteria LCA shows that it is most closely related to modern Epsilonproteobacteria, raising the possibility that it may have been characterized by a chemolithoautotrophic and anaerobic life-style. Our inference is based on data comprising between 43% (opisthokonta) and 86% (proteobacteria) of all gene families. Approaching LCA inference within a statistical framework renders the phylogenomic inference powerful and robust.

Physiological changes besides the enhancement of pigmentation in Petunia hybrida caused by overexpression of PhAN2, an R2R3-MYB transcription factor

Ectopic expression of PhAN2 in vegetative tissue can improve regeneration and adventitious rooting but inhibit axillary bud outgrowth of petunia, while overexpression specifically in flowers could shorten longevity. Anthocyanin 2 has been only treated as a critical positive regulation factor of anthocyanin biosynthesis in petunia flowers. To determine if this gene had other functions in plant growth, we overexpressed this gene in an an2 mutant petunia cultivar driven by promoters with different strengths or tissue specificity. Various physiological processes of transformants in different growth stages and environments were analyzed. Besides the expected pigmentation improvement in different tissues, the results also showed that ectopic expression of AN2 could improve the regeneration skill but inhibit the axillary bud germination of in vitro plants. Moreover, the rooting ability of shoot tips of transformants was significantly improved, while some transgenic lines' flower longevity was shortened. Gene expression analysis showed that the transcripts level of AN2, partner genes anthocyanin 1 (AN1), anthocyanin 11 (AN11), and target gene dihydroflavonol 4-reductase (DFR) was altered in the different transgenic lines. In addition, ethylene biosynthesis-related genes 1-aminocyclopropane-1-carboxylic acid synthase (ACS1) and ACC oxidase (ACO1) were upregulated in rooting and flower senescence processes but at different time points. Overall, our data demonstrate that the critical role of this AN2 gene in plant growth physiology may extend beyond that of a single activator of anthocyanin biosynthesis.

The effect of polyamines and silver thiosulphate on micropropagation of date palm followed by genetic stability assessment

There are some limitations in date palm micropropagation. These include low multiplication efficiency, low rooting rate, and high mortality experienced by in vitro raised plantlets during laboratory to soil transfer. The objective of the study was to determine the effect of the polyamines and Silver Thiosulphate (STS) on the enhancement of shoot multiplication and genetic stability of in vitro cultures of date palm cultivar Quntar. Media supplemented with 75 mg L^-1 SPD in combination with 10 mg L^-1 STS gave the highest percentage of callus producing buds (83.34%) and average bud formation (16.3) per jar. The addition of PUT and STS to the medium was most effective on root formation and the number of roots per shoot, where the best result, 91.67% and 6.37 roots per shoot, respectively, were obtained using 75 mg L^-1 PUT and 10 mg L^-1 STS, resulting in fast-growing plantlets during acclimatization phase, reaching 80% of plant survival. The genetic fidelity assessment of plants derived from micropropagation was confirmed by RAPD analysis. Four operon primers were used, and all of them showed amplified unambiguous (OPA02, OPC-04, OPD-07, and OPE-15). All generated bands were monomorphic and had no variation among the tissue culture-derived plants tested. Accordingly, these results indicate that adding polyamines and silver thiosulfate to the nutrient medium of date palm cv. Quntar was beneficial to improving shoot organogenesis, rooting, and production of genetically stable date palm plants.

Rooting Species Trees Using Gene Tree-Species Tree Reconciliation

Interpreting phylogenetic trees requires a root, which provides the direction of evolution and polarizes ancestor-descendant relationships. But inferring the root using genetic data is difficult, particularly in cases where the closest available outgroup is only distantly related, which are common for microbes. In this chapter, we present a workflow for estimating rooted species trees and the evolutionary history of the gene families that evolve within them using probabilistic gene tree-species tree reconciliation. We illustrate the pipeline using a small dataset of prokaryotic genomes, for which the example scripts can be run using modest computer resources. We describe the rooting method used in this work in the context or other rooting strategies and discuss some of the limitations and opportunities presented by probabilistic gene tree-species tree reconciliation methods.

Effects of different gelling agents on the different stages of rice regeneration in two rice cultivars

Plant tissue culture technology offers a solution for meeting the increasing commercial demand on economically important plants such as rice, a widespread dietary staple. However, significant genotype-specific morphogenetic responses constitute a considerable on rice regeneration in plant biotechnology contexts. Aside from genotype dependency, the components of the nutrient media including gelling agents have an important impact on regeneration efficiency. The current study explores the effect of different gelling agents on various stages of rice regeneration in two Egyptian rice cultivars-Sakha104 and Giza178. Media solidified with varying concentrations of a variety of gelling agents (agar, bacto agar, gelrite and phytagel) were tested for their impact on the frequency of callus induction, shoot regeneration and rooting. The results indicated gellan gum (gelrite and phytagel) was superior to agar products (agar and bacto agar) for callus induction. By contrast, no significant differences were found between different gelling agents for shoot regeneration. Gellan gum and media solidified with bacto agar were found to lead to significantly higher root regeneration than agar. The Sakha104 cultivar showed better responses than Giza 178 for callus induction and similar performance to the Giza 178 cultivar for root regeneration irrespective of the gelling agent. This work provides insights into the impact of different gelling agents on the morphogenetic response of two rice cultivars and can be used to help maximize the frequency of rice regeneration.

In vitro plant regeneration system for date palm (Phoenix dactylifera L.): effect of chelated iron sources

Background

Iron chelate sources and their concentrations are important factors in in vitro propagation of date palm. This study’s objective was to investigate the effect of the iron chelated form on the growth and development of tissue cultures of Barhee cultivar.

Results

The addition of FeEDDHA to the culture medium was more effective than FeEDTA on callus growth, shoot regeneration, and the number of shoots per jar, where the best result (220.8mg callus, 86.67% and 17.2 shoots per jar, respectively) was obtained by using 93.5 mg L⁻¹ FeEDDHA (5.6 mg L⁻¹ Fe), compared with other treatments. The results also indicate that using 93.5 mg L⁻¹ FeEDDHA (5.6 mg L⁻¹ Fe) as a supplement can decrease antioxidant enzymes CAT and POD activity compared to the rest of the treatments. Medium equipped with 187.0 mg L⁻¹ FeEDDHA (11.2 mg L⁻¹Fe) had the highest rooting percentage and number of roots per shoot than other treatments. The biochemical analysis results showed that treatments with FeEDDHA of 280.5 mg L⁻¹ (16.8 mg L⁻¹ Fe) and 187.0 mg L⁻¹ (11.2 mg L⁻¹Fe) significantly increased the iron content. The results showed that shoot maximum chlorophyll and endogenous IAA level content were recorded in a medium supplemented with 187.0 mg L⁻¹ FeEDDHA (11.2 mg L⁻¹Fe) as Fe source.

Conclusion

FeEDDHA used in the present study was proven to be a promising iron chelate source in comparison with the FeEDTA sources.

Optimization of growth regulators on in vitro propagation of Moringa stenopetala from shoot explants

Background

Moringa stenopetala belongs to the flowering family Moringaceae and genus Moringa. It is often referred to as the East African Moringa tree because it is native only to southern Ethiopia and northern Kenya. The expansion of its cultivation and utilization throughout the world especially in Africa is becoming important. For such expansion, the existing propagation method is limiting, so it needs a good propagation system to supply enough planting material with a uniform genotype. Therefore, the main objective of this study was to optimize an in vitro shoot multiplication protocol for M. stenopetala by using shoot tip as explants.

Results

Shoots were sterilized and cultured on Muraghige and Skoog (MS) medium for in vitro shoot initiation. For multiple shoot induction, the explants were cultured on MS medium supplemented with different concentrations of kinetin (0.5, 1.0, 1.5, 2.0, 2.5 mg/L) with Indole-3- butyric acid (IBA) or α -naphthalene acetic acid (NAA) (0.01, 0.1, 0.5 mg/L) and maintained at 25 ± 2 °C for four weeks. Rooting was achieved by culturing well developed shoots in half-strength MS medium containing IBA (0.1, 0.5, 1.0, 1.5, 2.0 mg/L), NAA (0.1, 0.5, 1.0, 1.5, 2.0 mg/L), and 0.5 mg/L IBA with NAA (0.1, 0.5, 1.0, 1.5, 2.0 mg/L). Statistical analysis revealed that there was a significant difference among all treatments applied in both shoot multiplication and rooting experiments. The maximum number of shoots per explant (3.43 ± 1.41) and 7.97 ± 4.18 leaves per explant were obtained on MS medium containing 0.5 mg/L kinetin with 0.01 mg/LNAA. The highest mean number of roots per shoot (1.63 ± 1.03) and mean root length (0.87 ± 1.22 cm) were obtained on MS medium containing 1.0 mg/LNAA and 0.1 mg/LIBA alone respectively. After acclimatization, 76% of plants were survived in the greenhouse.

Conclusion

In general, using NAA with kinetin for shoot multiplication was effective than kinetin with IBA. On the other hand, the application of 1.0 mg/L NAA alone and 1.0 mg/L NAA with 0.5 mg/L IBA were more effective for root induction.

Efficient direct shoot organogenesis and genetic stability in micropropagated sacha inchi (Plukenetia volubilis L.)

OBJECTIVE

It is necessary to improve biotech platforms based on in vitro cell tissue culture to support sacha inchi (Plukenetia volubilis L.) research programs and draw on the nutritional value of the high polyunsaturated fatty acid content of its oilseed. Here, we developed a rapid and efficient method for induction and direct in vitro shoot development for this species.

RESULTS

Shoots were generated from hypocotyl explants. The highest organogenic response was obtained in woody plant medium supplemented with 1 mg/L thidiazuron and 0.5 mg/L zeatin supplemented with L-glutamine, adenine hemisulfate, and L-arginine. Shoots obtained using this medium were transferred and subcultivated with different concentrations of indole-3-butyric acid and 1-naphthylacetic acid for rooting. For the first time, a histological analysis was performed supporting direct organogenic development in this species. The plantlets obtained were transferred ex vitro with a survival percentage of 80%. The genetic stability of the plants recovered was confirmed by randomly amplified polymorphic DNA analysis. All results indicate that it would be possible to stimulate direct shoot formation from hypocotyls to support the sustainable use of this species.

Quality and use of habitat patches by wild boar (Sus scrofa) along an urban gradient

Expansion and urbanization process of wild boar (Sus scrofa) populations lead to serious human-wildlife conflicts in many cities, e.g. in Budapest, Hungary. In this study we evaluated the penetration potential of the species into the inner urban areas by identifying the occurrence of wild boar and the quality of the habitat patches for them along an urban gradient from the periphery towards the centre. Wild boar rooting intensity, shrub cover and the availability of woody species giving favourable food to wild boar were measured in four different habitat patches. The availability of hiding shrub patches was much higher in the outer areas than in the inner ones. Similarly, the proportion of shrub and tree species providing favourable food for wild boar decreased towards the centre. Accordingly, we found rooting only in two areas nearer to the city boundary. Based on our results at the peripheral areas permanent presence of wild boar in near-natural habitats should be expected, but not in the inner green zones. We recommend to monitor the urban wild boar presence and evaluate the quality of urban green patches to mitigate problems related to the wild boars.

Effect of γ-radiation on post-harvest storage life and quality of onion bulb under ambient condition

Different doses of gamma Irradiation (0 Gy, 10 Gy, 60 Gy, 100 Gy and 200 Gy) were evaluated as potential treatment to extend the storage period and maintain the quality attributes of onion bulbs (cv. Punjab Noraya) at ambient temperature for a period of 144 days. It was observed that storage parameters such as physiological loss in weight, sprouting percentage, rotting percentage and quality traits like total soluble solids, firmness, color parameters, ascorbic acid and pyruvic acid varied significantly (p < 0.05) during storage period with respect to doses of irradiation. No rotting and sprouting were observed upto 24 days and 84 days, respectively in both gamma irradiated and un-irradiated bulbs. At 5 months of storage, the physiological loss in weight varied from 28.5 to 63.6% in all treatments. Physiological weight loss and rotting percentage were higher in the untreated (control) as well as bulbs radiated @ 10 Gy and 200 Gy. Firmness was better retained in the bulbs irradiated with gamma rays @ 120 Gy bulbs upto 84 days of storage. However, no clear-cut pattern for colour changes (L, a, b values) was observed with respect to the irradiation doses. TSS in bulbs decreased upto 36 days of storage and thereafter increased upto 48th day of storage irrespective of the dose of gamma irradiation. Ascorbic acid content of bulbs decreases significantly in all the irradiation treatments during storage but pyruvic acid initially increased, then decreased and again increased at the end of the storage period in un-irradiated and irradiated treatments. It is concluded that onion bulbs irradiated with gamma rays @ 120 Gy resulted in minimum loss in weight, rotting and sprouting while maintained best quality for 3 months of storage at ambient storage conditions.

Synthesis and bioactivity of indoleacetic acid-carbendazim and its effects on Cylindrocladium parasiticum

Indoleacetic acid (IAA)-carbendazim was synthesized to assess whether this conjugate could retain the fungicidal activity of carbendazim and gain root-inducing properties upon the addition of an indoleacetic acid group. An indoor virulence test demonstrated that the conjugate retained the fungicidal activity of carbendazim towards Cylindrocladium parasiticum. The conjugate was detected in roots after soaking Ricinus communis L. leaves into a solution of the IAA-carbendazim, which confirmed its phloem mobility. The activities of the cellulase, polygalacturonase and xylanase produced by Cylindrocladium parasiticum treated with different concentrations of the conjugate were determined, and the peak activities appeared at 72 h or 96 h. More importantly, the conjugate showed the ability to promote root growth. These results revealed that indoleacetic acid-carbendazim may be useful in preventing Cylindrocladium parasiticum and other diseases.

What is an archaeon and are the Archaea really unique?

The recognition of the group Archaea as a major branch of the tree of life (ToL) prompted a new view of the evolution of biodiversity. The genomic representation of archaeal biodiversity has since significantly increased. In addition, advances in phylogenetic modeling of multi-locus datasets have resolved many recalcitrant branches of the ToL. Despite the technical advances and an expanded taxonomic representation, two important aspects of the origins and evolution of the Archaea remain controversial, even as we celebrate the 40th anniversary of the monumental discovery. These issues concern (i) the uniqueness (monophyly) of the Archaea, and (ii) the evolutionary relationships of the Archaea to the Bacteria and the Eukarya; both of these are relevant to the deep structure of the ToL. To explore the causes for this persistent ambiguity, I examine multiple datasets and different phylogenetic approaches that support contradicting conclusions. I find that the uncertainty is primarily due to a scarcity of information in standard datasets-universal core-genes datasets-to reliably resolve the conflicts. These conflicts can be resolved efficiently by comparing patterns of variation in the distribution of functional genomic signatures, which are less diffused unlike patterns of primary sequence variation. Relatively lower heterogeneity in distribution patterns minimizes uncertainties and supports statistically robust phylogenetic inferences, especially of the earliest divergences of life. This case study further highlights the limitations of primary sequence data in resolving difficult phylogenetic problems, and raises questions about evolutionary inferences drawn from the analyses of sequence alignments of a small set of core genes. In particular, the findings of this study corroborate the growing consensus that reversible substitution mutations may not be optimal phylogenetic markers for resolving early divergences in the ToL, nor for determining the polarity of evolutionary transitions across the ToL.

In Vitro Propagation of Withania somnifera (L.) Dunal

Withania somnifera (L.) Dunal known as Ashwagandha is commonly used in traditional Indian medicine system. It possesses immense therapeutic value against a large number of ailments such as mental diseases, asthma, inflammation, arthritis, rheumatism, tuberculosis, and a variety of other diseases including cancer. The therapeutic potential of W. somnifera is due to the presence of secondary metabolites mainly, tropane alkaloids and withanolides (steroidal lactones). The growing realization of commercial value of the plant has initiated a new demand for in vitro propagation of elite chemotypes of Withania. Micropropagation which is an important tool for rapid multiplication requires optimization of number of factors such as nutrient medium, status of medium (solid and liquid), type of explant, and plant growth regulators. Similarly, an efficient and reproducible in vitro regeneration system which is a prerequisite for the development of genetic transformation protocol requires precise manipulation of various intrinsic and extrinsic factors.

Enhanced Indirect Somatic Embryogenesis from Shoot-Tip Explants of Date Palm by Gradual Reductions of 2,4-D Concentration

Shoot-tip explants obtained from offshoots of adult date palms are an excellent source for callus induction and subsequent somatic embryogenesis. In this protocol, the shoot-tip explants are transferred sequentially to a series of media containing gradually reduced concentrations of plant growth hormones: (a) 10 mg/L 2,4-dichlorophenoxy acetic acid (2,4-D) and 3 mg/L 2-isopentenyl adenine (2iP), (b) 7 mg/L 2,4-D and 1 mg/L 2iP, (c) 5 mg/L 2,4-D and 1 mg/L 2iP, and (d) 3 mg/L 2,4-D and 1 mg/L 2iP. Embryogenic callus differentiates into somatic embryos upon transfer to MS medium containing 0.5 mg/L abscisic acid (ABA) and 0.1 mg/L naphthalene acetic acid (NAA). Well-matured somatic embryos germinate on a medium containing 0.1 mg/L NAA. Repeated, multiple, and secondary somatic embryos are induced to produce normal well-developed somatic embryos upon transfer to MS medium containing 0.1 mg/L NAA and 0.05 mg/L benzyladenine (BA). This protocol is potentially applicable for commercial micropropagation of date palm.

Micropropagation of Ajuga species: a mini review

The genus Ajuga L., belonging to Lamiaceae family, is widespread. The demand for Ajuga species has risen sharply because of their medicinal, ornamental, and pharmacological properties. These wide-ranging plants are being rapidly depleted due to over-collection for ornamental and medicinal purposes, as well as by habitat destruction and deforestation. Ajuga boninsimae, A. bracteosa, A. ciliate, A. genevensis, A. incisa, A. makinoi, A. multiflora, A. pyramidalis, A. shikotanensis, A. reptans, and A. vestita are categorized and protected as endangered plants. In vitro plant culture has therefore emerged for the conservation and mass clonal propagation of rare plants. This mini-review covers the current in vitro scenario in the propagation of Ajuga species. Adventitious or axillary shoots are initiated on the leaf, petiole and internodes, as well as roots, nodes, and shoot tip explants. Shoot induction is predominantly dependent on plant growth regulators added to the culture medium. Full- or half-strength Murashige and Skoog medium with or without auxin is used for in vitro rooting. Rooted shoots need to be acclimatized in the greenhouse with an estimated 82-100% survival rate.

Akaryotes and Eukaryotes are independent descendants of a universal common ancestor

We reconstructed a global tree of life (ToL) with non-reversible and non-stationary models of genome evolution that root trees intrinsically. We implemented Bayesian model selection tests and compared the statistical support for four conflicting ToL hypotheses. We show that reconstructions obtained with a Bayesian implementation (Klopfstein et al., 2015) are consistent with reconstructions obtained with an empirical Sankoff parsimony (ESP) implementation (Harish et al., 2013). Both are based on the genome contents of coding sequences for protein domains (superfamilies) from hundreds of genomes. Thus, we conclude that the independent descent of Eukaryotes and Akaryotes (archaea and bacteria) from the universal common ancestor (UCA) is the most probable as well as the most parsimonious hypothesis for the evolutionary origins of extant genomes. Reconstructions of ancestral proteomes by both Bayesian and ESP methods suggest that at least 70% of unique domain-superfamilies known in extant species were present in the UCA. In addition, identification of a vast majority (96%) of the mitochondrial superfamilies in the UCA proteome precludes a symbiotic hypothesis for the origin of eukaryotes. Accordingly, neither the archaeal origin of eukaryotes nor the bacterial origin of mitochondria is supported by the data. The proteomic complexity of the UCA suggests that the evolution of cellular phenotypes in the two primordial lineages, Akaryotes and Eukaryotes, was driven largely by duplication of common superfamilies as well as by loss of unique superfamilies. Finally, innovation of novel superfamilies has played a surprisingly small role in the evolution of Akaryotes and only a marginal role in the evolution of Eukaryotes.

In vitro propagation and assessment of genetic stability of acclimated plantlets of Cornus alba L. using RAPD and ISSR markers

Cornus alba L. (white dogwood) is an important ornamental shrub having a wide range of applications such as reforestation programs and soil retention systems. The vegetative propagation of dogwood by cuttings may be slow, difficult, and cultivar dependent; therefore, an improved micropropagation method was developed. Nodal stem segments of C. alba cultivars 'Aurea' and 'Elegantissima' were cultured on media enriched with six different sources of macronutrients. Media were supplemented with either N6-benzyladenine (BA) or thidiazuron (TDZ) in combination with 1-naphthaleneacetic acid (NAA). Regardless of the cultivar, the best shoot proliferation was observed on Lloyd and McCown medium (woody plant medium (WPM)) at pH 6.2, containing 1.0 mg L-1 BA, 0.1 mg L-1 NAA, and 20-30 g L-1 sucrose. Rooting of regenerated shoots was achieved by an in vitro method when different concentrations of NAA or indole-3-butyric acid (IBA) were tested. Microcuttings were rooted for 8 wk on medium enriched with 0.25 mg L-1 NAA and potted into P9 containers in the greenhouse. The final survival rate of the plants after 20 wk was 80% for 'Aurea' and 90% for 'Elegantissima'. Genetic stability of the micropropagated plants was confirmed by using two DNA-based molecular marker techniques. A total of 30 random amplified polymorphic DNA (RAPD) and 20 inter-simple sequence repeat (ISSR) primers resulted in 197-199 and 184-187 distinct and reproducible band classes, respectively, in 'Aurea' and 'Elegantissima' plantlets. All of the RAPD and ISSR profiles were monomorphic and comparable with the mother plant.

CuO Nanoparticles Inhibited Root Growth from Brassica nigra Seedlings but Induced Root from Stem and Leaf Explants

Interests associated with nanoparticles (NPs) are budding due to their toxicity to living species. The lethal effect of NPs depends on their nature, size, shape, and concentration. Present investigation reports that CuO NPs badly affected Brassica nigra seed germination and seedling growth parameters. However, variation in antioxidative activities and nonenzymatic oxidants is observed in plantlets. Culturing the leaf and stem explants on MS medium in presence of low concentration of CuO NPs (1-20 mg l^-1) produces white thin roots with thick root hairs. These roots also show an increase in DPPH radical scavenging activity (up to 80 % at 10 mg l^-1), total antioxidant, and reducing power potential (maximum in presence of 10 mg l^-1 CuO NPs in the media). Nonenzymatic antioxidative molecules, phenolics and flavonoids, are observed elevated but NPs concentration dependent. We can conclude that CuO NPs can induce rooting from plant explants cultured on appropriate medium. These roots can be explored for the production of active chemical constituents.

Comparative transcriptional analysis provides new insights into the molecular basis of adventitious rooting recalcitrance in Eucalyptus

Adventitious rooting (AR) is essential in clonal propagation. Eucalyptus globulus is relevant for the cellulose industry due to its low lignin content. However, several useful clones are recalcitrant to AR, often requiring exogenous auxin, adding cost to clonal garden operations. In contrast, E. grandis is an easy-to-root species widely used in clonal forestry. Aiming at contributing to the elucidation of recalcitrance causes in E. globulus, we conducted a comparative analysis with these two species differing in rooting competence, combining gene expression and anatomical techniques. Recalcitrance in E. globulus is reversed by exposure to exogenous indole-3-acetic acid (IAA), which promotes important gene expression modifications in both species. The endogenous content of IAA was significantly higher in E. grandis than in E. globulus. The cambium zone was identified as an active area during AR, concentrating the first cell divisions. Immunolocalization assay showed auxin accumulation in cambium cells, further indicating the importance of this region for rooting. We then performed a cambium zone-specific gene expression analysis during AR using laser microdissection. The results indicated that the auxin-related genes TOPLESS and IAA12/BODENLOS and the cytokinin-related gene ARR1may act as negative regulators of AR, possibly contributing to the hard-to-root phenotype of E. globulus.

Dissecting the role of two cytokinin analogues (INCYDE and PI-55) on in vitro organogenesis, phytohormone accumulation, phytochemical content and antioxidant activity

There is a continuous search for new chemical entities to expand the collection of suitable compounds to increase the efficiency of micropropagation protocols. Two cytokinin (CK) analogues, 2-chloro-6-(3-methoxyphenyl)aminopurine (INCYDE) and CK antagonist 6-(2-hydroxy-3-methylbenzylamino)purine (PI-55) were used as a tool to elucidate the auxin-CK crosstalk under in vitro conditions in the medicinally important plant, Eucomis autumnalis subspecies autumnalis. These compounds were tested at 0.01, 0.1 and 10 μM alone as well as in combination with benzyladenine (BA) and naphthaleneacetic acid (NAA). The organogenesis, phytohormone content, phytochemical and antioxidant response in 10 week-old-in vitro regenerated E. autumnalis subspecies autumnalis was evaluated. INCYDE generally favoured shoot regeneration while the effect of PI-55 was more evident in root proliferation. Overall, INCYDE promoted the accumulation of higher concentrations and varieties of endogenous CK relative to the PI-55 treatments. In contrast, higher concentration of indole-3-acetic acid and 2-oxindole-3-acetic acid were generally observed in PI-55-supplemented cultures when compared to plantlets derived from INCYDE. Both CK analogues (individually and in-conjunction with exogenously applied PGRs) significantly influenced the phytochemicals and consequently the antioxidant potential of the in vitro regenerants. These results provided insight on how to alleviate root inhibition, a problem which causes considerable loss of several elite species during micropropagation.

Plant regeneration from organogenic callus and assessment of clonal fidelity in Elephantopus scaber Linn., an ethnomedicinal herb

An efficient callus induction and plant regeneration system has been standardized for an ethnomedicinal plant, Elephantopus scaber Linn. Two explants i. e. seeds and leaf segments were used for callus induction. Murashige and Skoog (MS) medium supplemented with 5.0 μM 2, 4-dichlorophenoxy acetic acid (2, 4-D) and 0.5 μM kinetin (Kn) gave the optimum frequency (89 %) of callus induction from seed explant. The results showed that the highest response in terms of percent callus regenerating (91 %) and number of shoots (56) per culture was recorded on MS medium supplemented with 6.0 μM N6-benzylaminopurine (BA) and 1.5 μM α naphthalene acetic acid (NAA). The best rooting of regenerated shoots was obtained on half strength MS medium supplemented with 6.0 μM indole-3- butyric acid (IBA). On this medium, 100 % of the shoots produced roots with a mean number of 3.2 roots per shoot. The positive role of vesicular arbuscular mycorrhizae (VAM) along with potting mix has been well established in the present study. Of the various potting mix employed for plant acclimatization, the highest response of 100 % plant survival was noticed when autoclaved garden soil, sand (2:1) and VAM was utilized as potting mix. Inter-simple sequence repeats (ISSR) were used to establish the clonal fidelity of regenerated plantlets and the banding profiles from callus derived plants were monomorphic and similar to those of mother plant, thus ascertaining the true-to-type nature of these plants.

Optimizing culture media for in vitro proliferation and rooting of Tetra (Prunus empyrean 3) rootstock

The enormous demand for new rootstock genotypes in Prunus spp. makes us to use micropropagation as an unavoidable propagation method. Therefore, the study on micropropagation of a new semi-dwarf vegetative rootstock namely Tetra (Prunus empyrean 3) was carried out to develop an optimized protocol. Culture establishment using nodal segments was enhanced using WPM (woody plant medium) medium lacking growth regulators. From various shoot multiplication treatments, the highest number of shoots per explant (30.4) was found on ME (Media created specifically) medium supplemented with 0.8 mg l^-1 BAP and 0.05 mg l^-1 IBA. 100% in vitro rooting was achieved on ½ strength MS medium with 0.5 mg l^-1 IBA, 1.6 mg l^-1 thiamine and 150 mg l^-1 iron sequestrene.

Factors affecting efficient in vitro micropropagation of Muscari muscarimi Medikus using twin bulb scale

Endemic Muscari muscarimi Medikus is the most fragrant plant among Muscari species and has a high ornamental potential. The natural populations of M. muscarimi, are severely affected by increased environmental pollution and urbanization. There is a need to develop a micropropagation method that should serve effectively for commercial propagation and conservation. Therefore, the study targeted to set up a strategy for efficient in vitro bulblet regeneration system of M. muscarimi using twin scale bulb explants on 1.0 × MS medium containing 4.44, 8.88, 17.76 μM BAP (6-Benzylaminopurine) plus 2.685, 5.37, 10.74 μM NAA (α-Naphthalene acetic acid). Maximum number of 19 daughter axillary bulblets and 16 daughter adventitious bulblets per twin bulb scale explant was regenerated on 1.0 × MS medium containing 17.76 μM BAP plus 10.74 μM NAA and 17.76 μM BAP plus 2.685 μM NAA respectively. The daughter bulblets regenerated on twin bulb scales on 8 out of 9 regeneration treatment could be easily rooted on 1.0 × MS medium containing 4.9 μM IBA (Indole-3-butyric acid). The daughter bulblets regenerated on 9th treatment (1.0 × MS medium containing 17.76 μM BAP plus 10.74 μM NAA) were transferred to 1.0 × MS medium containing 30 g/l sucrose to break negative carry over effect of this dose of BAP-NAA, where they grew 2-3 roots of variable length. Daughter bulblet diameter was increased by culturing them on 1.0 × MS medium containing 4.44 μM BAP plus 5.37 μM NAA. The results verified that both age and the source of explants had significant effect on regeneration. In another set of experiments, twin scales were obtained from in vitro regenerated daughter bulblets, although they induced bulblets, yet their bulblet regeneration percentage, mean number of bulblets per explant and their diameter were significantly reduced. In vitro regenerated bulblets were acclimatized in growth chamber under ambient conditions of temperature and humidity on peat moss, where they flowered. The study provides important information about selection of suitable micropropagation medium, strategies to improve bulblet diameter and rooting of M. muscarimi which offers a scope for commercial propagation.

Plant regeneration via somatic embryogenesis and shoot organogenesis from immature cotyledons of Camellia nitidissima Chi

Camellia nitidissima Chi (Theaceae) is a world-famous economic and ornamental plant with golden-yellow flowers. It has been classified as one of the rarest and most endangered plants in China. Our objective was to induce somatic embryogenesis, shoot organogenesis and plant regeneration for C. nitidissima. Three types of callus (whitish, reddish and yellowish) were induced from immature cotyledons on improved woody plant medium (WPM) with different plant growth regulators (PGRs). Among the callus, whitish callus was induced by 4.5 μM 2,4-dichlorophenoxyacetic acid (2,4-D) and reddish and yellowish callus were induced by strongly active cytokinins, thidiazuron (TDZ) or 6-benzylaminopurine (BAP), singly or combined with weakly active auxin, α-naphthaleneacetic acid (NAA). The embryogenic callus could differentiate into somatic embryos, nodular embryogenic structures (large embryo-like structures) or adventitious shoots depending on the PGR used in WPM. BAP was best for adventitious buds and zeatin was best for somatic embryogenesis while kinetin (Kt) was best for the formation of nodular embryogenic structures. The three regeneration pathways often occurred in the same embryogenic callus clumps. Most shoots (80.0%) developed roots in WPM supplemented with 24.6 μM IBA and 0.3 μM NAA while 47.5% of somatic embryos could germinate directly and develop into plantlets on induction medium supplemented with 0.9 μM BAP and 0.1 μM NAA. The nodular embryogenic structures could be sub-cultured and cyclically developed in one of two differentiation pathways: shoot organogenesis or somatic embryogenesis. Plantlets derived from shoot buds rooted and somatic embryos germinated when transplanted into soil in a greenhouse; 66.7% of plantlets from shoot culture and 78.6% of plantlets from somatic embryos survived after 8 weeks' acclimatization.

An optimal protocol for in vitro regeneration, efficient rooting and stable transplantation of chickpea

A rapid, reproducible and efficient regeneration method was developed for chickpea (Cicer arietinum L.) using single cotyledon with half embryonal axis as explants. MS medium supplemented with 4 ìM TDZ, 10 ìM 2-iP and 2 ìM kinetin induced 50-100 adventitious buds/shoots after 14 days of culture and elongated on MS medium supplemented with 5 ìM 2-iP and 2 ìM kinetin. Healthy, strong and 100 % rooting was achieved by exposing cut ends of the shoots to 10 sec pulse treatment with 100 ìmoles/ml IBA followed by their transfer to liquid MS basal medium within 10-14 d. 2-3 cm long shoots were most suitable for rooting. Potting-mixture with good aeration and lesser capacity to retain water was most suitable for achieving successful establishment of chickpea plantlets. Garden soil mixed with sand (gravel) and bio-manure in the ratio of 1:1:1 is most suitable for achieving cent percent transplantation success. Cent percent of plantlets got acclimatized, survived in the pots and showed normal growth, development, flowering followed by podding and seeds setting. Harvesting of seeds was done after the pods were fully matured and dry. In this communication, we have demonstrated for the first time that shoot length, pulse treatment of cut ends of shoots with 100 ìmoles/ml IBA and aeration of potting mixture are key factors for rapid micro-propagation and successful establishment of chickpea.

Influence of the antibiotic timentin on plant regeneration of tomato (Lycopersicon esculentum Mill.) cultivars

 Cotyledon explants of tomato (Lycopersicon esculentum Mill. cvs 'Santa Clara', 'Firme' mutant, 'IPA-5' and 'IPA-6') were excised from 8- to 10-day-old in vitro-grown seedlings. Four different shoot induction media supplemented with timentin (300 mg l^-1) were screened. When cotyledon explants were cultured on MS-based medium with 1.0 mg l^-1 zeatin plus 0.1 mg l^-1 IAA and supplemented with timentin, higher regeneration frequencies and a greater number of elongated shoots were obtained. It was observed that timentin caused an increase in the morphogenesis of in vitro cotyledon explants of tomato cultivars. In two of three cultivars tested, rooting of shoots was positively influenced, both in the presence and absence of timentin in the rooting medium, among shoots regenerated from explants derived from timentin-supplemented medium. The results confirm those of a previous investigation on the beneficial effects of this class of antibiotics on tomato regeneration and, consequently, its reliability for use in the transformation of this species.

Rooting dynamics of Medicago sativa seedlings growing in association with Bothriochloa caucasica

Medicago sativa was seeded into an established sward of Bothriochloa caucasica. Two frequencies of sward defoliation were compared to a nondefoliated control. Although 84 to 92% of the root mass at 0-20 cm belonged to B. caucasica during the spring and summer samplings, defoliation generally reduced the root mass of B. caucasica. During the summer, aboverground mass of B. caucasica ranged from 735 to 1220 g m^-2 and 295 to 410 g m^-2 for control and defoliation treatments, respectively. Defoliation apparently reduced the competitive effects of B. caucasica on M. sativa, as taproot and lateral root mass of M. sativa was much higher in defoliated than in control plots by the end of the growing season. Predawn xylem potential of M. sativa was 0.4 to 0.8 MPa more negative in control than in defoliated plots from mid-summer to fall. Thus, we suggest that the transpirational demand of undefoliated B. caucasica reduced soil moisture available to M. sativa, thereby reducing its growth and survival during late summer and fall, compared to defoliated treatments.