A shared response of thaumatin like protein, chitinase, and late embryogenesis abundant protein3 to environmental stresses in tea [Camellia sinensis (L.) O. Kuntze]

Molecular characterization revealed the role of thaumatin-like proteins of Rhizoctonia solani AG4-JY in inducing maize disease resistance

The gene family of thaumatin-like proteins (TLPs) plays a crucial role in the adaptation of organisms to environmental stresses. In recent years, fungal secreted proteins (SP) with inducing disease resistance activity in plants have emerged as important elicitors in the control of fungal diseases. Identifying SPs with inducing disease resistance activity and studying their mechanisms are crucial for controlling sheath blight. In the present study, 10 proteins containing the thaumatin-like domain were identified in strain AG4-JY of Rhizoctonia solani and eight of the 10 proteins had signal peptides. Analysis of the TLP genes of the 10 different anastomosis groups (AGs) showed that the evolutionary relationship of the TLP gene was consistent with that between different AGs of R. solani. Furthermore, it was found that RsTLP3, RsTLP9 and RsTLP10 were regarded as secreted proteins for their signaling peptides exhibited secretory activity. Prokaryotic expression and enzyme activity analysis revealed that the three secreted proteins possess glycoside hydrolase activity, suggesting they belong to the TLP family. Additionally, spraying the crude enzyme solution of the three TLP proteins could enhance maize resistance to sheath blight. Further analysis showed that genes associated with the salicylic acid and ethylene pathways were up-regulated following RsTLP3 application. The results indicated that RsTLP3 had a good application prospect in biological control.

Hydropriming and Osmotic Priming Induce Resistance against Aspergillus niger in Wheat (Triticum aestivum L.) by Activating β-1, 3-glucanase, Chitinase, and Thaumatin-like Protein Genes

Priming is used as a method to improve plant growth and alleviate the detrimental effects of pathogens. The present study was conducted to evaluate the effects of different priming methods in the context of resistance to Aspergillus niger in wheat (Triticum aestivum L.). Here, we show that different priming treatments—viz., hydropriming, osmotic priming, halopriming, and hormonal priming techniques can induce disease resistance by improving the biochemical contents of wheat, including chlorophyll, protein, proline, and sugar. In addition, physiological parameters—such as root length, shoot length, fresh and dry root/shoot ratios, and relative water content were positively affected by these priming methods. In essence, hydropriming and osmotic priming treatments were found to be more potent for enhancing wheat biochemical contents, along with all the physiological parameters, and for reducing disease severity. Hydropriming and osmotic priming significantly decreased disease severity, by 70.59−75.00% and 64.71−88.33%, respectively. RT-PCR and quantitative real-time PCR analyses of potentially important pathogenesis-related (PR)-protein genes (Thaumatin-like protein (TLP), chitinase, and β-1,3-glucanase) in primed plants were evaluated: β-1,3-glucanase was most highly expressed in all primed plants; Chitinase and TLP exhibited higher expression in hormonal-, halo-, osmotic-, and hydro-primed plants, respectively. These results suggest that the higher expression of β-1,3-glucanase, TLP, and chitinase after hydropriming and osmotic priming may increase disease resistance in wheat. Our study demonstrates the greater potential of hydropriming and osmotic priming for alleviating stress caused by A. niger inoculation, and enhancing resistance to it, in addition to significantly improving plant growth. Thus, these priming methods could be beneficial for better plant growth and disease resistance in other plants.

Dynamic changes in metabolic and lipidomic profiles of tea plants during drought stress and re-watering

Tea (Camellia sinensis L.), as an evergreen plant, needs a humid environment. Water deficit would diminish tea yield and quality. We analyzed the dynamic changes in the metabolite and lipid profiling of tea leaves under various drought conditions and re-watering to determine the metabolic changes in tea leaves responding to drought challenges. In all, 119 metabolites showed substantial alterations in drought-stressed tea plants, including sugars and sugar alcohols, amino acids, and tricarboxylic acid cycle intermediates and lipids. We detected 29 lipids and they were classified into phosphatidylglycerol (PG), phosphatidic acid (PA), sulfoquinovosyl-diacylglycerol (SQDG), phosphatidylcholine (PC), lyso-phosphatidylcholine (LysoPC), and phosphatidylinositol (PI). The levels of sugar, sugar alcohol, and sugar precursors may change as a response to drought stress. Compared with these metabolites, the membrane lipids showed more dynamic changes in tea under drought stresses. Furthermore, metabolic recovery was only partial, with the majority of the examined metabolites exhibiting significantly different levels between samples from re-watered and well-watered tea plants. The findings also showed that comprehensive metabolomic and lipidomic approaches were efficient in elucidating the impacts of drought stress on tea plant metabolism. Our findings are valuable for understanding the mechanisms behind drought tolerance in tea plants from the metabolism perspective and utilizing the compounds to improve the drought tolerance of tea plants.

BolTLP1, a Thaumatin-like Protein Gene, Confers Tolerance to Salt and Drought Stresses in Broccoli (Brassica oleracea L. var. Italica)

Plant thaumatin-like proteins (TLPs) play pleiotropic roles in defending against biotic and abiotic stresses. However, the functions of TLPs in broccoli, which is one of the major vegetables among the B. oleracea varieties, remain largely unknown. In the present study, bolTLP1 was identified in broccoli, and displayed remarkably inducible expression patterns by abiotic stress. The ectopic overexpression of bolTLP1 conferred increased tolerance to high salt and drought conditions in Arabidopsis. Similarly, bolTLP1-overexpressing broccoli transgenic lines significantly improved tolerance to salt and drought stresses. These results demonstrated that bolTLP1 positively regulates drought and salt tolerance. Transcriptome data displayed that bolTLP1 may function by regulating phytohormone (ABA, ethylene and auxin)-mediated signaling pathways, hydrolase and oxidoreductase activity, sulfur compound synthesis, and the differential expression of histone variants. Further studies confirmed that RESPONSE TO DESICCATION 2 (RD2), RESPONSIVE TO DEHYDRATION 22 (RD22), VASCULAR PLANT ONE-ZINC FINGER 2 (VOZ2), SM-LIKE 1B (LSM1B) and MALATE DEHYDROGENASE (MDH) physically interacted with bolTLP1, which implied that bolTLP1 could directly interact with these proteins to confer abiotic stress tolerance in broccoli. These findings provide new insights into the function and regulation of bolTLP1, and suggest potential applications for bolTLP1 in breeding broccoli and other crops with increased tolerance to salt and drought stresses.

BolTLP1, a Thaumatin-like Protein Gene, Confers Tolerance to Salt and Drought Stresses in Broccoli (Brassica oleracea L. var. Italica)

Plant thaumatin-like proteins (TLPs) play pleiotropic roles in defending against biotic and abiotic stresses. However, the functions of TLPs in broccoli, which is one of the major vegetables among the B. oleracea varieties, remain largely unknown. In the present study, bolTLP1 was identified in broccoli, and displayed remarkably inducible expression patterns by abiotic stress. The ectopic overexpression of bolTLP1 conferred increased tolerance to high salt and drought conditions in Arabidopsis. Similarly, bolTLP1-overexpressing broccoli transgenic lines significantly improved tolerance to salt and drought stresses. These results demonstrated that bolTLP1 positively regulates drought and salt tolerance. Transcriptome data displayed that bolTLP1 may function by regulating phytohormone (ABA, ethylene and auxin)-mediated signaling pathways, hydrolase and oxidoreductase activity, sulfur compound synthesis, and the differential expression of histone variants. Further studies confirmed that RESPONSE TO DESICCATION 2 (RD2), RESPONSIVE TO DEHYDRATION 22 (RD22), VASCULAR PLANT ONE-ZINC FINGER 2 (VOZ2), SM-LIKE 1B (LSM1B) and MALATE DEHYDROGENASE (MDH) physically interacted with bolTLP1, which implied that bolTLP1 could directly interact with these proteins to confer abiotic stress tolerance in broccoli. These findings provide new insights into the function and regulation of bolTLP1, and suggest potential applications for bolTLP1 in breeding broccoli and other crops with increased tolerance to salt and drought stresses.

The future of high-quality Ceylon tea seems bleak in the face of climate change

Understanding the interactive effects and relationships between biochemical elements of tea leaves and the related factors, particularly climatic, cultivar, and geographic, is key for high-quality Ceylon tea production. The objectives of this study were to (1) investigate the effects of season × cultivar × agro-ecological regions (AERs) on the four tested biochemicals in fresh tea leaves, total polyphenol content (TPC), free sugar, protein, and theanine; (2) determine the relationships between, and develop a model to estimate, the biochemicals and their related factors; and (3) project the potential concentrations and distributions of four tested biochemicals in tea leaves with respect to the current and future climate. This study primarily uses inferential statistics via the Statistical Package for the Social Sciences (SPSS), cross-validation using R software, and the inverse distance weighting (IDW) approach in ArcGIS. The results demonstrate that the season, cultivar (Ceylon tea cultivars of TRI 2025 and TRI 4053), and AER and their interactions on biochemicals have significant effects (p < 0.05). The models derived in the regression analysis demonstrate the strong relationships between the independent variables and the biochemicals, with multiple correlation coefficients (R) around 0.8 and coefficient of determination (R2) around 0.6. The low standard deviation of error of prediction (SDEP < 0.1) and the high correlation coefficient of leave-one-out cross-validation (Q2) for all four biochemicals ranged from 0.56 to 0.61, which signifies the predictive ability of the models. The future projections show a considerable increase in the thresholds of all tested biochemicals. The distribution category with 'very high' concentrations of TPC and theanine is predicted to increase in the future by averages of 10% and 14%, respectively, while reducing the classes of protein and free sugar by 14% and 12%, respectively. Overall, the changing concentrations of the thresholds of relevant biochemicals and their distribution will negatively affect the final quality of tea, and these variations indicate that climate change has started to diminish Ceylon tea quality.

Molecular regulation of anthocyanin discoloration under water stress and high solar irradiance in pluckable shoots of purple tea cultivar

During water-deficit stress, antioxidant enzymes use anthocyanin molecules as co-substrates to scavenge for reactive oxygen species leading to reduced anthocyanin content and ultimately loss of purple leaf pigmentation in tea. Anthocyanins are an important class of flavonoids responsible for liquor color and market acceptability of processed tea from the anthocyanin-rich purple tea cultivar 'TRFK 306'. However, the color in pluckable shoots fade and turn green during the dry and hot season, before rapidly reverting back to purple when weather is favorably wet and cool/cold. Our study revealed that loss of purple leaf pigmentation correlated well with reduced precipitation, high soil water-deficit, increased intensity and duration of sunlight and temperature. Richly purple pigmented leaves harvested during the cool, wet conditions recorded significantly higher anthocyanin content compared to faded samples harvested during the dry season. Similarly, individual anthocyanins were affected by seasonal changes with malvidin being the most abundant. Comparative transcriptomics of two RNA-seq libraries, dry/discolored and wet/colored seasons, revealed depression of most metabolic processes related to anthocyanin accumulation in dry conditions. Specifically, transcripts encoding pathway regulators, MYB-bHLH-WD40 (MBW) complex, were repressed possibly contributing to the suppression of late biosynthetic genes of the pathway. Further, suppression of anthocyanin transport genes could be linked to reduced accumulation of anthocyanin in the vacuole during the dry season. However, slight increase in expression of some transporter and reactive oxygen species (ROS) antioxidant genes in the discolored leaf suggests non-enzymatic degradation of anthocyanin, ultimately leading to loss of purple color during the dry season. Based on increased expression of ROS antioxidant genes (especially catalase and superoxide dismutase) in the discolored leaf, we speculate that anthocyanins are used as co-substrates by antioxidant enzymes to scavenge for ROS (especially hydrogen peroxide) that escape from organelles, leading to reduced anthocyanins and loss of pigmentation during the dry season.

Membrane localized thaumatin-like protein from tea (CsTLP) enhanced seed yield and the plant survival under drought stress in Arabidopsis thaliana

Thaumatin-like proteins (TLPs) are pathogenesis-related (PR5) proteins, which are induced in response to various biotic and abiotic stresses. The present work was carried out to clone TLP of Camellia sinensis (CsTLP) and to evaluate the response of transgenic lines of Arabidopsis constitutively expressing CsTLP under drought conditions. Data showed that transgenic lines exhibited lower relative electrolyte leakage and higher water retention capacity as compared to the wild-type (WT) plants under drought stress. In addition, results with confocal microscopy showed CsTLP + GFP fusion protein to be localized in the cell membrane which moved to the intercellular spaces under prolonged drought stress. Expression of CsTLP enhanced seed yield and the plant survival in transgenic lines as compared to the WT plants under drought stress. Results suggested the importance of CsTLP in improving drought tolerance in Arabidopsis.

Fulvic acid ameliorates drought stress-induced damage in tea plants by regulating the ascorbate metabolism and flavonoids biosynthesis

Background

Fulvic acid (FA) is a kind of plant growth regulator, which can promote plant growth, play an important role in fighting against drought, improve plant stress resistance, increase production and improve quality. However, the function of FA in tea plants during drought stress remain largely unknown.

Results

Here, we examined the effects of 0.1 g/L FA on genes and metabolites in tea plants at different periods of drought stress using transcriptomics and metabolomics profiles. Totally, 30,702 genes and 892 metabolites were identified. Compared with controlled groups, 604 and 3331 differentially expressed metabolite genes (DEGs) were found in FA-treated tea plants at 4 days and 8 days under drought stress, respectively; 54 and 125 differentially expressed metabolites (DEMs) were also found at two time points, respectively. Bioinformatics analysis showed that DEGs and DEMs participated in diverse biological processes such as ascorbate metabolism (GME, AO, ALDH and L-ascorbate), glutathione metabolism (GST, G6PDH, glutathione reduced form and CYS-GYL), and flavonoids biosynthesis (C4H, CHS, F3’5’H, F3H, kaempferol, quercetin and myricetin). Moreover, the results of co-expression analysis showed that the interactions of identified DEGs and DEMs diversely involved in ascorbate metabolism, glutathione metabolism, and flavonoids biosynthesis, indicating that FA may be involved in the regulation of these processes during drought stress.

Conclusion

The results indicated that FA enhanced the drought tolerance of tea plants by (i) enhancement of the ascorbate metabolism, (ii) improvement of the glutathione metabolism, as well as (iii) promotion of the flavonoids biosynthesis that significantly improved the antioxidant defense of tea plants during drought stress. This study not only confirmed the main strategies of FA to protect tea plants from drought stress, but also deepened the understanding of the complex molecular mechanism of FA to deal with tea plants to better avoid drought damage.

Combating Climate Change in the Kenyan Tea Industry

Climate change triggered by global warming poses a major threat to agricultural systems globally. This phenomenon is characterized by emergence of pests and diseases, extreme weather events, such as prolonged drought, high intensity rains, hailstones and frosts, which are becoming more frequent ultimately impacting negatively to agricultural production including rain-fed tea cultivation. Kenya is predominantly an agricultural based economy, with the tea sector generating about 26% of the total export earnings and about 4% gross domestic product (GDP). In the recent years, however, the country has witnessed unstable trends in tea production associated with climate driven stresses. Toward mitigation and adaptation of climate change, multiple approaches for impact assessment, intensity prediction and adaptation have been advanced in the Kenyan tea sub-sector. Further, pressure on tea breeders to release improved climate-compatible cultivars for the rapidly deteriorating environment has resulted in the adoption of a multi-targeted approach seeking to understand the complex molecular regulatory networks associated with biotic and abiotic stresses adaptation and tolerance in tea. Genetic modeling, a powerful tool that assists in breeding process, has also been adopted for selection of tea cultivars for optimal performance under varying climatic conditions. A range of physiological and biochemical responses known to counteract the effects of environmental stresses in most plants that include lowering the rates of cellular growth and net photosynthesis, stomatal closure, and the accumulation of organic solutes such as sugar alcohols, or osmolytes have been used to support breeding programs through screening of new tea cultivars suitable for changing environment. This review describes simulation models combined with high resolution climate change scenarios required to quantify the relative importance of climate change on tea production. In addition, both biodiversity and ecosystem based approaches are described as a part of an overall adaptation strategy to mitigate adverse effects of climate change on tea in Kenya and gaps highlighted for urgent investigations.

Structural responses of kiwifruit allergen Act d 2 to thermal and electric field stresses based on molecular dynamics simulations and experiments

Kiwifruit is considered to be the most common plant-based food causing allergic reactions, after peanuts, soybeans, and wheat.

The late embryogenesis abundant gene family in tea plant (Camellia sinensis): Genome-wide characterization and expression analysis in response to cold and dehydration stress

Late embryogenesis abundant (LEA) proteins are a large and highly diverse family of polypeptides that play important roles in plant growth, development and stress responses. At present, LEA gene families have been identified and systematically characterized in many plant species. However, the LEA gene family in tea plant has not been revealed, and the biological functions of the members of this family remain unknown. In this study, 33 CsLEA genes were identified from tea plant via a genome-wide study, and they were clustered into seven groups according to analyses of their phylogenetic relationships, gene structures and protein conserved motifs. In addition, expression analysis revealed that the CsLEA genes were specifically expressed in one or more tissues and significantly induced under cold and dehydration stresses, implying that CsLEA genes play important roles in tea plant growth, development and response to cold and dehydration stresses. Furthermore, a potential transcriptional regulatory network, including DREB/CBF, MYB, bZIP, bHLH, BPC and other transcription factors, is directly associated with the expression of CsLEA genes, which may be ubiquitous and important in the above mentioned processes. This study could help to increase our understanding of CsLEA proteins and their contributions to stress tolerance in tea plant.

A Comprehensive Review on Kiwifruit Allergy: Pathogenesis, Diagnosis, Management, and Potential Modification of Allergens Through Processing

Kiwifruit is rich in bioactive components including dietary fibers, carbohydrates, natural sugars, vitamins, minerals, omega-3 fatty acids, and antioxidants. These components are beneficial to boost the human immune system and prevent cancer and heart diseases. However, kiwifruit is emerging as one of the most common elicitors of food allergies worldwide. Kiwifruit allergy results from an abnormal immune response to kiwifruit proteins and occur after consuming this fruit. Symptoms range from the oral allergy syndrome (OAS) to the life-threatening anaphylaxis. Thirteen different allergens have been identified in green kiwifruit and, among these allergens, Act d 1, Act d 2, Act d 8, Act d 11, and Act d 12 are defined as the "major allergens." Act d 1 and Act d 2 are ripening-related allergens and are found in abundance in fully ripe kiwifruit. Structures of several kiwifruit allergens may be altered under high temperatures or strong acidic conditions. This review discusses the pathogenesis, clinical features, and diagnosis of kiwifruit allergy and evaluates food processing methods including thermal, ultrasound, and chemical processing which may be used to reduce the allergenicity of kiwifruit. Management and medical treatments for kiwifruit allergy are also summarized.

Osmotin: A plant defense tool against biotic and abiotic stresses

Plants are prone to a number of pathogens and abiotic stresses that cause various disorders. However, plants possess a defense mechanism to cope with these stresses. The osmotin protein belongs to the PR-5 family of Pathogenesis-related (PR) proteins, which are produced in response to diseases caused by various biotic and abiotic stresses. Osmotin uses a signal transduction pathway to inhibit the activity of defensive cell wall barriers and increases its own cytotoxic efficiency. However, in response to cytotoxic effects, this pathway stimulates a mitogen-activated protein kinase (MAPK) cascade that triggers changes in the cell wall and enables osmotin's entrance into the plasma membrane. This mechanism involves cell wall binding and membrane perturbation, although the complete mechanism of osmotin activity has not been fully elucidated. Osmotin possesses an acidic cleft that is responsible for communication with its receptor in the plasma membrane of fungi. Osmotin is also involved in the initiation of apoptosis and programmed cell death, whereas its overexpression causes the accumulation of proline in transgenic plants. A higher concentration of osmotin can cause the lysis of hyphae tips. This review highlights the role of osmotin protein in the plant defense mechanism and its mode of action against numerous pathogens in wild and transgenic plants.

iTRAQ-based quantitative proteomic analysis of wheat roots in response to salt stress

Salinity is a major abiotic stress that affects plant growth and development. Plant roots are the sites of salt uptake. Here, an isobaric tag for a relative and absolute quantitation based proteomic technique was employed to identify the differentially expressed proteins (DEPs) from seedling roots of the salt-tolerant genotype Han 12 and the salt-sensitive genotype Jimai 19 in response to salt treatment. A total of 121 NaCl-responsive DEPs were observed in Han 12 and Jimai 19. The main DEPs were ubiquitination-related proteins, transcription factors, pathogen-related proteins, membrane intrinsic protein transporters and antioxidant enzymes, which may work together to obtain cellular homeostasis in roots and to determine the overall salt tolerance of different wheat varieties in response to salt stress. Functional analysis of three salt-responsive proteins was performed in transgenic plants as a case study to confirm the salt-related functions of the detected proteins. Taken together, the results of this study may be helpful in further elucidating salt tolerance mechanisms in wheat.

A thaumatin-like protein of Ocimum basilicum confers tolerance to fungal pathogen and abiotic stress in transgenic Arabidopsis

Plant often responds to fungal pathogens by expressing a group of proteins known as pathogenesis-related proteins (PRs). The expression of PR is mediated through pathogen-induced signal-transduction pathways that are fine-tuned by phytohormones such as methyl jasmonate (MeJA). Here, we report functional characterization of an Ocimum basilicum PR5 family member (ObTLP1) that was identified from a MeJA-responsive expression sequence tag collection. ObTLP1 encodes a 226 amino acid polypeptide that showed sequence and structural similarities with a sweet-tasting protein thaumatin of Thaumatococcus danielli and also with a stress-responsive protein osmotin of Nicotiana tabacum. The expression of ObTLP1 in O. basilicum was found to be organ-preferential under unstressed condition, and responsive to biotic and abiotic stresses, and multiple phytohormone elicitations. Bacterially-expressed recombinant ObTLP1 inhibited mycelial growth of the phytopathogenic fungi, Scleretonia sclerotiorum and Botrytis cinerea; thereby, suggesting its antifungal activity. Ectopic expression of ObTLP1 in Arabidopsis led to enhanced tolerance to S. sclerotiorum and B. cinerea infections, and also to dehydration and salt stress. Moreover, induced expression of the defense marker genes suggested up-regulation of the defense-response pathways in ObTLP1-expressing Arabidopsis upon fungal challenge. Thus, ObTLP1 might be useful for providing tolerance to the fungal pathogens and abiotic stresses in crops.

The α-Crystallin Domain Containing Genes: Identification, Phylogeny and Expression Profiling in Abiotic Stress, Phytohormone Response and Development in Tomato (Solanum lycopersicum)

The α-crystallin domain (ACD) is an ancient domain conserved among all kingdoms. Plant ACD proteins have roles in abiotic stresses, transcriptional regulation, inhibiting virus movement, and DNA demethylation. An exhaustive in-silico analysis using Hidden Markov Model-based conserved motif search of the tomato proteome yielded a total of 50 ACD proteins that belonged to four groups, sub-divided further into 18 classes. One of these groups belongs to the small heat shock protein (sHSP) class of proteins, molecular chaperones implicated in heat tolerance. Both tandem and segmental duplication events appear to have shaped the expansion of this gene family with purifying selection being the primary driving force for evolution. The expression profiling of the Acd genes in two different heat stress regimes suggested that their transcripts are differentially regulated with roles in acclimation and adaptive response during recovery. The co-expression of various genes in response to different abiotic stresses (heat, low temperature, dehydration, salinity, and oxidative stress) and phytohormones (abscisic acid and salicylic acid) suggested possible cross-talk between various members to combat a myriad of stresses. Further, several genes were highly expressed in fruit, root, and flower tissues as compared to leaf signifying their importance in plant development too. Evaluation of the expression of this gene family in field grown tissues highlighted the prominent role they have in providing thermo-tolerance during daily temperature variations. The function of three putative sHSPs was established as holdase chaperones as evidenced by protection to malate-dehydrogenase against heat induced protein-aggregation. This study provides insights into the characterization of the Acd genes in tomato and forms the basis for further functional validation in-planta.

Comparative proteomic responses of two bermudagrass (Cynodon dactylon (L). Pers.) varieties contrasting in drought stress resistance

Drought (water-deficit) stress is a serious environmental problem in plant growth and cultivation. As one of widely cultivated warm-season turfgrass, bermudagrass (Cynodon dactylon (L). Pers.) exhibits drastic natural variation in the drought stress resistance in leaves and stems of different varieties. In this study, proteomic analysis was performed to identify drought-responsive proteins in both leaves and stems of two bermudagrass varieties contrasting in drought stress resistance, including drought sensitive variety (Yukon) and drought tolerant variety (Tifgreen). Through comparative proteomic analysis, 39 proteins with significantly changed abundance were identified, including 3 commonly increased and 2 decreased proteins by drought stress in leaves and stems of Yukon and Tifgreen varieties, 2 differentially regulated proteins in leaves and stems of two varieties after drought treatment, 23 proteins increased by drought stress in Yukon variety and constitutively expressed in Tifgreen variety, and other 3 differentially expressed proteins under control and drought stress conditions. Among them, proteins involved in photosynthesis (PS), glycolysis, N-metabolism, tricarboxylicacid (TCA) and redox pathways were largely enriched, which might be contributed to the natural variation of drought resistance between Yukon and Tifgreen varieties. These studies provide new insights to understand the molecular mechanism underlying bermudagrass response to drought stress.

RNA-seq-mediated transcriptome analysis of actively growing and winter dormant shoots identifies non-deciduous habit of evergreen tree tea during winters

Tea [Camellia sinensis (L.) O. Kuntze] is a perennial tree which undergoes winter dormancy and unlike deciduous trees, the species does not shed its leaves during winters. The present work dissected the molecular processes operating in the leaves during the period of active growth and winter dormancy through transcriptome analysis to understand a long-standing question: why should tea be a non-deciduous species? Analyses of 24,700 unigenes obtained from 57,767 primarily assembled transcripts showed (i) operation of mechanisms of winter tolerance, (ii) down-regulation of genes involved in growth, development, protein synthesis and cell division, and (iii) inhibition of leaf abscission due to modulation of senescence related processes during winter dormancy in tea. These senescence related processes exhibited modulation to favour leaf abscission (i) in deciduous Populustremula during winters, and (ii) also in tea but under osmotic stress during which leaves also abscise. These results validated the relevance of the identified senescence related processes for leaf abscission and suggested their operation when in need in tea.

The GATA and SORLIP motifs in the 3-hydroxy-3-methylglutaryl-CoA reductase promoter of Picrorhiza kurrooa for the control of light-mediated expression

Light upregulates the expression of 3-hydroxy-3-methylglutaryl-CoA reductase (HMGR) in Picrorhiza kurrooa, an endangered medicinal herb. Upstream sequences of HMGR of P. kurrooa (PropkHMGR) were analyzed in relation to its role in light-mediated regulation of gene expression. GATA motif in PropkHMGR exhibited stronger DNA-protein interaction with the nuclear extract of dark-exposed plants in contrast to SORLIP that exhibited stronger binding with the nuclear extract of light-exposed plants. Analysis of PropkHMGR (PropkHMGR-D1, -1,059/-1) and its deletion fragments PropkHMGR-D2 (-825/-1), PropkHMGR-D3 (-651/-1), PropkHMGR-D4 (-452/-1), and PropkHMGR-D5 (-101/-1) in Arabidopsis thaliana showed PropkHMGR to regulate gene expression [β-glucuronidase (GUS) was used as a reporter gene] at all the developmental stages but only in actively dividing tissues, excluding anthers. Whereas, PropkHMGR-D2 regulated GUS expression in relatively older seedlings but the expression was observed only in shoot apical meristem, root tips, and anthers. PropkHMGR-mediated gene expression was higher in dark as compared to that in the light in Arabidopsis across four temperatures studied. As opposed to the results in P. kurrooa, GATA motifs exhibited DNA-protein interaction with nuclear extract of light-exposed plants of Arabidopsis. SORLIP motifs in Arabidopsis also exhibited DNA-protein interaction with nuclear extract of light-exposed plants as in P. kurrooa. Data showed that (1) PropkHMGR regulated light-mediated gene expression and (2) GATA motif exhibited an inverse relationship between strength of DNA-protein interaction and the gene expression whereas the relationship was species specific for SORLIP.