Drought-stress induced changes of fatty acid composition affecting sunflower grain yield and oil quality

Water availability is the most important key factor affecting sunflower productivity and its oil quality. This study investigated the effect of drought stress on sunflower fatty acids and its effects on grain yield and related components. Thirteen sunflower hybrids were evaluated as randomized complete block design with three replications under normal and drought stress conditions in Karaj, Iran, during 2 years (2019 and 2020). Drought stress was imposed by water withholding during the reproductive stage. Drought stress accelerated the maturity of sunflower and caused a reduction in grain yield (30%), grains weight (11%), and grain numbers/head (22%) compared with normal irrigation. Means of grain yield were 2.7 and 1.8 t/ha under normal and drought stress conditions respectively. Grain numbers/head had higher correlation with grain yield than grains weight under both conditions. Among the fatty acids, the contents of palmitic and linoleic acids were increased (11% and 3%, respectively) while stearic and oleic acids were decreased (6% and 11%). The results indicated that sunflower hybrids benefit from the escape strategy differentially to adapt drought stress condition. However, this adaptation changes sunflower fatty acid profile that reduces grain yield and quality of sunflower oil in Karaj conditions in Iran. In order to achieve the higher yields and higher oil quality, it is necessary to avoid drought stress in sunflower production fields.

Genotype by yield* trait (GYT) biplot analysis: A novel approach for phenotyping sunflower single cross hybrids based on multiple traits

Sunflower is one of the most important oilseed plants in the world and its oil has nutritional and high economic value. Selection of high-yielding hybrids is important in sunflower breeding. In this regard, 11 new hybrids along with four cultivars were evaluated in a randomized complete block design with four replications during the 2018-2020 growing seasons. The phenological and agronomic traits including days to flowering, days to ripening, plant height, stem diameter, head diameter, seed number per head, thousand-seed weight, oil content, and seed yield were measured. In this study, the methods of genotype × trait (GT) and genotype × yield × trait biplot (GYT) were used to identify interrelationships between different traits and to select the best sunflower hybrids based on multiple traits. According to the results, GYT biplot method was more efficient compared to the GT biplot method. Considering both superiority index (SI) and GYT biplot, the genotypes G8, G11, G5, and G3 were superior in terms of agronomical attributes such as flowering and maturity times, stem and head diameter, plant height, thousand-seed weight, and seed number per head in close relationship with grain yield. Oil content of the hybrids G8, G11, G5, and G3 was 47.9%, 46.4%, 45.8%, and 46.3%, respectively. The results indicated that there is a potential for simultaneous genetic improvement of the characteristics (i.e., plant height, thousand-seed weight, seed number per head, early maturity) in sunflower. Overall, the GYT graphical biplot method provides a practical and efficient new approach for the identification of suitable hybrids according to the set of intended characteristics in sunflower improvement under multi-years or multi-locations.

Water deficit stress changes in physiological, biochemical and antioxidant characteristics of anise (Pimpinella anisum L.)

This study was designed to evaluate the impact of water deficit stress on the seed yield and its components, physiological functions, fatty acid content and compositions, essential oil (EO) content and compositions, phenolic acids and flavonoids amounts, and antioxidant activities of anise seeds. Plants evaluations were performed under well-watered (WW), moderate water deficit stressed (MWDS), and severe water deficit stressed (SWDS). The results revealed that SWDS significantly reduced seed yield, branch number per plant, seed number, umbel number, and thousand seed weight. Water deficit stress also caused a decrease in chlorophyll content, relative water content, quantum efficiency of photosystem II, and cell membrane stability, while increasing leaf temperature. The analysis of fatty acid composition indicated that petroselinic acid was the main fatty acid and its percentage increased by 8.75% and 14.60% under MWDS and SWDS, respectively. Furthermore, MWDS increased the EO content by 1.48 times, while it decreased by 41.32% under SWDS. The chemotype of EO was altered from t-anethole/estragole in WW seeds to t-anethole/β-bisabolene in treated seeds. Higher levels of total phenolics were detected in stressed seeds. Water deficit stress increased the amount of the major class, naringin, by 1.40 and 1.26 times under MWDS and SWDS. The evaluation of antioxidant activity through reducing power, DPPH, and chelating ability assays indicated that stressed seeds exhibited the highest activity. The study's findings suggest that the application of drought stress before harvesting can regulate the production of bioactive compounds, which can affect the industrial and nutritional values of anise seeds.

Exploring the quantitative genetics of traits associated with drought tolerance and yield in Pimpinella anisum L. under different water regimes

MAIN CONCLUSION

Genetic improvement of seed yield and drought resistance could be simultaneously gained in anise when breeding for drought resistance. Improving the water use efficiency of anise is a primary objective of anise breeding programs aimed at mitigating the impacts of drought stress. This study aimed to determine the predominant mechanisms involved in drought tolerance and investigate the genetic control of associated traits with drought tolerance and higher grain yield. According to these aims, 10 half-diallel hybrids and their five parents were evaluated in both field and greenhouse lysimetric experiments under well-watered and water deficit stress conditions. The results indicated that the inheritance of grain yield is complex and affected by water deficit stress. Similar heritability and genetic architecture were detected for flowering time and percentages of photosynthate partitioned to grain (PPPG) in both well-watered and water deficit stress treatments. Significant negative genetic correlations were observed between grain yield and flowering time, root dry mass, root diameter, root volume, root number, percentages of photosynthate partitioned to shoot, and percentages of photosynthate partitioned to root. Therefore, the selection of low values of these attributes can be used to improve grain yield under drought conditions. In contrast, a positive significant genetic linkage between grain yield and PPPG, chlorophyll content, cell membrane stability, and leaf relative water content reveal selection for high values of these attributes is favored. These attributes could be used as surrogate selection criteria in the early segregating generations. The P₁ parent (early ripening parent) contained key genes associated with PPPG and drought escape. It was concluded that improvement of drought tolerance and grain yield could be simultaneously achieved in anise breeding programs.

Dissection of Genetic Effects, Heterosis, and Inbreeding Depression for Phytochemical Traits in Coriander

Increasing seed yield, fatty acids, and essential oil content are the main objectives in breeding coriander. However, in order to achieve this, there is a need to understand the nature of gene action and quantify the heterosis and inbreeding depression. Towards this, six genetically diverse parents, their 15 F₁ one-way hybrids, and 15 F₂ populations were evaluated under different water treatments. The genetic effects of general (GCA) and specific combining ability (SCA) and their interactions with water treatment were significant for five traits. Water deficit stress decreased all traits in both F₁ and F₂ generations except for the essential oil content, which was significantly increased due to water deficit stress. Under water deficit stress, a non-additive gene action was predominant in the F₁ generation, while an additive gene action was predominant in the F₂ generation for all the traits except seed yield under severe water deficit stress. There was a positive high heterosis for the traits examined in some hybrids. Furthermore, in the F₂ generation, even after inbreeding depression, some promising populations displayed appropriate mean performance. The results show that the parents used for crossing had a rich, diverse gene pool for the traits studied. Therefore, selection between the individuals of relevant F₂ populations could be used to develop high yielding hybrids or superior lines.

Phenotyping new rapeseed lines based on multiple traits: Application of GT and GYT biplot analyses

The selection based on multiple traits enhances the crop cultivars merit to farmers. In this regard, 19 breeding lines as well as two commercial cultivars were studied using a randomized complete block design (RCBD) with three replications in three locations during the 2020-2021 growing season. In this study, to identify the association among different traits and to select the best rapeseed lines based on multiple traits, genotype × trait (GT) and genotype × yield × trait (GYT) biplot analyses were used. The results showed that using GYT biplot is more efficient than GT biplot. Based on the GYT biplot and superiority index (SI), the breeding lines G16 and G18 were considered as superior genotypes in combination with the agronomical traits, that is, 1000-seed weight, number of seeds per pod, number of pods per plant, number of lateral branches, plant height, and pod length with seed yield, which represents a genetic gain in rapeseed breeding program. Based on seed yield combination with phenological traits (early maturity), the breeding line G15 was selected as the best one. Moreover, the line G2 was defined as the superior one in combination of seed yield with pod length. The results indicated that there is a potential for simultaneous genetic improvement of the characteristics (i.e., plant height, number of seeds per pod, early maturity) in rapeseed. Generally, the graphical method of the GYT biplot represented an efficient and practical new way to recognize superior genotypes based on multiple traits in rapeseed breeding programs.

Genetic combining ability of coriander genotypes for agronomic and phytochemical traits in response to contrasting irrigation regimes

Knowledge of genetic combining ability and gene action would help breeders to choose suitable parents and devise an appropriate breeding strategy for coriander. In the present study, six diverse genotypes of coriander, their 15 F₁s and 15 F₂s were evaluated through randomized complete block design with three replications to study genetic combining ability for agronomic and phytochemical traits in coriander. Plants were subjected to well-watered (WW), mild water-deficit stress (MWDS) and severe water-deficit stress (SWDS) irrigation regimes. The results indicate that water-deficit stress decreased all of the measured traits in both the F₁ and F₂ generations. General combining ability and specific combining ability effects were highly significant for all of the traits in both the F₁ and F₂ generations. Additive gene action was predominant for phonology and fruit yield component traits in all irrigation regimes in both the F₁ and F₂ generations. For fatty acid content and total lipid yield, non-additive gene action was predominant in the F₁ generation while additive gene action was predominant in the F₂ generation under MWDS and SWDS conditions. The P₄ parent had the highest general combining ability for fruit yield components in both the F₁ and F₂ generations. The P₆ parent had the highest general combining ability for phenological and phytochemical traits. The P₄ and P₆ parents are promising material to develop early flowering and early maturing genotypes coupled with high total lipids in advanced generations of segregation.

Differential expression of a cysteine proteinase and cystatin pair as side­by­side fusion forms in Escherichia coli

As a basic study, the fusion expressions of two functionally related proteins were described. The side by side fusion construction, expression, purification and functional characterization of Arabidopsis papain-like cysteine proteinase (CP) and cysteine proteinase inhibitor (CPI) were successfully carried out by using an Escherichia coli expression system without affecting the recombinant bacterial growth. The purification products of two different fused constructs designated as «R1: H2N-maltose binding protein-CPI-CP-COOH and R2: H2N-maltose binding protein-CP-CPI-COOH» showed inverse enzymatic/inhibitory activities, in vitro. Analysis of the constructs by using computational tools revealed that the arrangement of CP/CPI pair in fusion forms might be the important criteria for proper tertiary organization, structural folding and functional property. The overall results showed that the C-terminally located molecule could be the active folded structure in each fusion construct. The achievements of the present work may be utilized in a specific protein engineering application such as manufacturing the novel switchable expression systems in the future.

The possible involvement of D-amino acids or their metabolites in Arabidopsis cysteine proteinase/cystatin N-dependent proteolytic pathway

Cysteine proteinases and their inhibitors 'cystatins' play essential roles in plant growth and development. They are involved in various signaling pathways and in the response to wide ranges of biotic and abiotic environmental stresses. To investigate their possible influence from D-amino acids or their metabolism in vivo, Arabidopsis seedlings were allowed to grow under four physicochemically different D-amino acids including D-aspartate, D-serine, D-alanine and D-phenylalanine containing media. The reverse transcription polymerase chain reaction (R T-PCR) analysis of cysteine proteinase and cystatin gene expressions showed that the addition of D-amino acid to the plant growth media considerably induce the expression of proteinase transcript while decrease the expression level of inhibitor gene in the leaf and root tissues of the test plant in overall. Based on the obtained results the potential impact of D-amino acids or their metabolism on the activity of cysteine proteinase/cystatin-dependent proteolytic apparatus as well as their possible cooperation were predicted and discussed in the plant system.

Maltose-binding protein switches programmed cell death in Nicotiana glutinosa leaf cells

Maltose-binding protein (MBP) is a part of the complex regulatory and transport maltose system of Escherichia coli that is responsible for the uptake and efficient catabolism of maltodextrins through the transmembrane signaling at the expense of ATP. In the present work, this bacterial periplasmic protein was identified as a cell death inducer in Nicotiana glutinosa plant. Upon exogenous application at the concentrations more than 50 microg/ml, purified MBP protein induced wilting and localized cell death on the leaves of test plant. DNA fragmentation assay and antioxidant enzymes activity test showed that the induced cell death might be programmed. It was predicted that maltose-binding protein signals programmed cell death (PCD) upstream of reactive oxygen species (ROS) and DNA fragmentation processes in the test plant leaves. However, it needs to be clarified that how MBP switches and signals PCD in plant tissues.

Differential fusion expression and purification of a cystatin in two different bacterial strains

To date, the identification of the novel multifunctional properties of cysteine proteinase inhibitors "known as cystatins" is the great of interests for molecular biologists. The efficient production, purification and correctly folded form of these proteins are the most important requirements for their any basic research. To the best of our knowledge, maltose-binding protein (MBP) fusion tags are being used to overcome the impediment to their heterologous recombinant expression in Escherichia coli as insoluble and bio-inactive inclusion bodies. In the present work, to evaluate the expression efficiency of a cystatin molecule in E. coli cells by using MBP tags, the expression of Celosia cystatin was studied in two different strains of this bacterium. The quantitative analysis results based on the one-step purification yield of the fused product showed the excellency of the E. coli TB1 strain in comparison to E. coli DH5alpha for the high-level production of active product.

Comparative fusion expression of maize SINAT5 in two different strains of Escherichia coli

SINAT5 is a plant E3 ligase that regulates auxin signaling and root morphogenesis by ubiquitination of the NAC1 protein. Consequently, it may be a putative regulator of aspects of plant development cycles that are controlled by auxin. Efficient production, purification and correctly folded form of this protein are important requirements for functional studies. We produced and quantitatively compared fusion expression of the "maltose binding protein (mbp)-maize sinat5" construct in two different strains of Escherichia coli. One-step purification of fused products gave about 33 mg protein/L bacterial cell culture for E. coli TB1 cells and approximately 18 mg protein/L bacterial cell culture for E. coli DH5α cells. Continuous expression of the fused product and similarity of growth patterns were observed in both cultures.

Genome wide cloning of maize meiotic recombinase Dmc1 and its functional structure through molecular phylogeny

The development of meiotic division and associated genetic recombination paved the way for evolutionary changes. However, the secondary and tertiary structure and functional domains of many of the proteins involved in genetic recombination have not been studied in detail. We used the human Dmc1 gene product along with secondary and tertiary domain structures of Escherichia coli RecA protein to help determine the molecular structure and function of maize Dmc1, which is required for synaptonemal complex formation and cell cycle progression. The maize recombinase Dmc1 gene was cloned and characterized, using rice Dmc1 cDNA as an orthologue. The deduced amino acid sequence was used for elaborating its 3-D structure, and functional analysis was made with the CDD software, showing significant identity of the Dmc1 gene product in Zea mays with that of Homo sapiens. Based on these results, the domains and motives of WalkerA and WalkerB as ATP binding sites, a multimer site (BRC) interface, the putative ssDNA binding L1 and L2 loops, the putative dsDNA binding helix-hairpin-helix, a polymerization motif, the subunit rotation motif, and a small N-terminal domain were proposed for maize recombinase Dmc1.

Early detection of immunization: a study based on an animal model using 1H nuclear magnetic resonance spectroscopy

Vaccines require a period of at least three months for clinical trials, hence a method that can identify elicitation of immune response a few days after the first dose is a necessity. Evolutionary variable selections are modeling approaches for proper manipulation of available data which were used to set up an animal model for classification of time dependent 1HNMR metabolomic profiles and pattern recognition of fluctuations of metabolites in two groups of male rabbits. One group of rabbits was immunized with human red blood cells and the other used as control. Blood was obtained every 48 h from each rabbit for a period of six weeks and the serum monitored for antibodies and metabolites by 1HNMR spectra. Evaluation of data was carried out using orthogonal signal correction followed by principal component analysis and partial least square. A neural network was also set up to predict immunization profiles. A distinct separation in patterns of significant metabolites was obtained between the two groups, just a few days after the first and the second dose. These metabolites were used as targets of neural networks where each sample was used as test, validation and training and their quantitative influence predicted by regression. This model could be used for prediction of immunization in rabbits a few days after the first dose with 96% accuracy. Similar animals and human vaccine trials would assist greatly in reaching early conclusions in advance of the usual two month immunization schedule; resulting in an appreciable saving of cost and time.

Over-expression, purification and functional characterization of Celosia ClpS as a fused protein in Escherichia coli

A ClpS homologue from Celosia cristata was expressed as maltose-binding fusion protein under the control of strong inducible tac promoter of pMALc2X vector in TB 1 strain of Escherichia coli. SDS-PAGE analysis showed that fused ClpS is produced as about 63 kDa protein in recombinant bacteria. Expressed product was purified to homogeneity with a yield of about 31 mg/l of bacterial culture. The results indicated that heterologous expression of Celosia ClpS does not affect bacterial growth under different induced conditions. Total cellular antioxidant assessment results revealed that the induction of ClpS activates the bacterial antioxidative system. Since, the purified ClpS did not exhibit antioxidant activity in vitro, we speculated a functional corelation between bacterial protelolytic apparatus and its anti-oxidative system. This prediction may contribute to our better understanding of functional relationship between proteolytic and antioxidative systems in biological worlds in the future investigations.

Molecular cloning and expression in Escherichia coli of an active fused Zea mays L. D-amino acid oxidase

D-Amino acid oxidase (DAAO) is an FAD-dependent enzyme that metabolizes D-amino acids in microbes and animals. However, such ability has not been identified in plants so far. We predicted a complete DAAO coding sequence consisting of 1158 bp and encoding a protein of 386 amino acids. We cloned this sequence from the leaf cDNA population of maize plants that could utilize D-alanine as a nitrogen source and grow normally on media containing D-Ala at the concentrations of 100 and 1000 ppm. For more understanding of DAAO ability in maize plant, we produced a recombinant plasmid by the insertion of isolated cDNA into the pMALc2X Escherichia coli expression vector, downstream of the maltose-binding protein coding sequence. The pMALc2X-DAAO vector was used to transform the TB1 strain of E. coli cells. Under normal growth conditions, fused DAAO (with molecular weight of about 78 kDa) was expressed up to 5 mg/liter of bacterial cells. The expressed product was purified by affinity chromatography and subjected to in vitro DAAO activity assay in the presence of five different D-amino acids. Fused DAAO could oxidize D-alanine and D-aspartate, but not D-leucine, D-isoleucine, and D-serine. The cDNA sequence reported in this paper has been submitted to EMBL databases under accession number AM407717.

Effects of different plant density and nitrogen application rate on nitrogen use efficiency of potato tuber

In order to investigate the plant density and nitrogen level on nitrogen use efficiency components (agronomical, physiological, apparent recovery and nitrogen use efficiency), the amount of nitrogen uptake by plant, yield and yield components of potato (Solanum tuberosum L.) Agria cultivars' tuber, a factorial experiment based on randomized complete block design was conducted in Ardabil, Iran, in 2006 with three replications. Factors were adjusted for the nitrogen level (0, 80, 160 and 200 kg ha(-1) net nitrogen) and plant density (5.5, 7.5 and 11 plant m(-2)). Results showed that with increasing the nitrogen levels and plant densities agronomical nitrogen use efficiency, physiological nitrogen efficiency and nitrogen use efficiency were decreased and apparent recovery nitrogen efficiency was increased. The most nitrogen uptake in plant was observed at the 200 kg ha(-1) net nitrogen. The most yield and number of tuber per unit area were gained at the 80 and 160 kg ha(-1) net nitrogen. Increasing the plant density resulted in increasing in the tuber yield per unit area and the rate of nitrogen up to the 160 kg ha(-1) net nitrogen. So, application of the 80 kg ha(-1) net nitrogen and plant density of 11 plant m(-2) is recommended to get highest yield with the most nitrogen use efficiency.

Cloning and expression of small cDNA fragment encoding strong antiviral peptide from Celosia cristata in Escherichia coli

A small cDNA fragment containing a ribosome-inactivating site was isolated from the leaf cDNA population of Celosia cristata by polymerase chain reaction (PCR). PCR was conducted linearly using a degenerate primer designed from the partially conserved peptide of ribosome-inactivating/antiviral proteins. Sequence analysis showed that it is 150 bp in length. The cDNA fragment was then cloned in a bacterial expression vector and expressed in Escherichia coli as a ~57 kD fused protein, and its presence was further confirmed by Western blot analysis. The recombinant protein was purified by affinity chromatography. The purified product showed strong antiviral activity towards tobacco mosaic virus on host plant leaves, Nicotiana glutinosa, indicating the presence of a putative antiviral determinant in the isolated cDNA product. It is speculated that antiviral site is at, or is separate but very close to, the ribosome-inactivating site. We nominate this short cDNA fragment reported here as a good candidate to investigate further the location of the antiviral determinants. The isolated cDNA sequence was submitted to EMBL databases under accession number of AJ535714.