Drought-sensitive Lines Research Articles

Utilizing transcriptomics and metabolomics to unravel key genes and metabolites of maize seedlings in response to drought stress

BackgroundDrought stress can substantially restrict maize growth and productivity, and global warming and an increasing frequency of extreme weather events are likely to result in more yield losses in the future. Therefore, unraveling the molecular mechanism underlying the response to drought stress is essential for breeding drought-resilient crops.ResultsIn this study, we subjected the 3-leaf-period plants of two maize inbred lines, a drought-tolerant line (si287) and a drought-sensitive line (X178), to drought stress for seven days while growing in a chamber. Subsequently, we measured physiological traits and analyzed transcriptomic and metabolic profiles of two inbred lines. Our KEGG analysis of genes and metabolites revealed significant differences in pathways related to glycolysis/gluconeogenesis, flavonoid biosynthesis, starch and sucrose metabolism, and biosynthesis of amino acids. Additionally, our joint analysis identified proline, tryptophan and phenylalanine are crucial amino acids for maize response to drought stress. Furthermore, we concentrated on tryptophan (Trp), which was found to enhance tolerance via IAA-ABA signaling, as well as SA and nicotinamide adenine dinucleotide (NAD) consequent reactive oxygen species (ROS) scavenging. We identified three hub genes in tryptophan biosynthesis, indole-3-acetaldehyde oxidase (ZmAO1, 542,228), catalase 1 (ZmCAT1, 542,369), and flavin-containing monooxygenase 6 (ZmYUC6, 103,629,142), High expression of these genes plays a significant role in regulating drought tolerance. Two metabolites related to tryptophan biosynthesis, quinolinic acid, and kynurenine improved maize tolerance to drought stress by scavenging reactive oxygen species.ConclusionsThis study illuminates the mechanisms underlying the response of maize seedlings to drought stress. Especially, it identifies novel candidate genes and metabolites, enriching our understanding of the role of tryptophan in drought stress. The identification of distinct resistance mechanisms in maize inbred lines will facilitate the exploration of maize germplasm and the breeding of drought-resilient hybrids.

Metabolic and transcriptomic profiling during wheat seed development under progressive drought conditions

Globally, bread wheat (Triticum aestivum) is one of the most important staple foods; when exposed to drought, wheat yields decline. Although much research has been performed to generate higher yield wheat cultivars, there have been few studies on improving end-product quality under drought stress, even though wheat is processed into flour to produce so many foods, such as bread, noodles, pancakes, cakes, and cookies. Recently, wheat cultivation has been affected by severe drought caused by global climate change. In previous studies, seed shrinkage was observed in wheat exposed to continuous drought stress during seed development. In this study, we investigated how progressive drought stress affected seed development by metabolomic and transcriptomic analyses. Metabolite profiling revealed the drought-sensitive line reduced accumulation of proline and sugar compared with the water-saving, drought-tolerant transgenic line overexpressing the abscisic acid receptor TaPYL4 under drought conditions in spikelets with developing seeds. Meanwhile, the expressions of genes involved in translation, starch biosynthesis, and proline and arginine biosynthesis was downregulated in the drought-sensitive line. These findings suggest that seed shrinkage, exemplifying a deficiency in endosperm, arose from the hindered biosynthesis of crucial components including seed storage proteins, starch, amino acids, and sugars, ultimately leading to their inadequate accumulation within spikelets. Water-saving drought tolerant traits of wheat would aid in supporting seed formation under drought conditions.

Selection of oat (Avena sativa L.) drought-tolerant genotypes based on multiple yield-associated traits.

Most plant breeding and agricultural practices are based on selecting genotypes for yield. However, this is inadequate to screen crop varieties for specific attributes, such as drought tolerance. In this study, we quantified the response of oat (Avena sativa L.) plant physiological and morphological traits to drought stress and selected some key traits to establish a genotype by yield*trait (GYT)-based method for ranking 30 oat genotypes. The effectiveness of this method was also evaluated under drought conditions. Water-deficit treatment significantly reduced leaf chlorophyll, root morphological traits, groat yield and associated components, such as mean grain weight. We observed that the genotypes 'JUSTICE' and 'BOLINA' had the smallest and largest yield loss, respectively, after exposure to drought stress, but showed opposite trends in the biomass allocation of roots and grains. This indicated that drought tolerance was highly dependent on the distribution of photoassimilates. Our results also illustrated that the GYT method is a trade-off approach and more effective in selecting oat ideotypes under drought conditions than the yield-related index method because it combines yield, yield stability, and related agronomic traits in the calculation process. Drought-tolerant genotypes had more biomass allocated to roots and grains with higher chlorophyll content and better root structure, e.g. longer root lengths than drought-sensitive lines. By integrating yield and yield-related traits, the GYT approach is more practical than traditional single-trait selection methods when assessing drought tolerance. © 2023 His Majesty the King in Right of Canada. Journal of The Science of Food and Agriculture published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry. Reproduced with the permission of the Minister of Agriculture and Agri-Food Canada.

Transcriptome and metabolome profiling of interspecific CSSLs reveals general and specific mechanisms of drought resistance in cotton.

In order to understand the molecular mechanism of cotton's response to drought during the flowering and boll stage, transcriptomics and metabolomics were carried out for two introgression lines (drought-tolerant line: T307; drought-sensitive line: S48) which were screened from Gossypium hirsutum cv. 'Emian22' with some gene fragments imported from Gossypium barbadense acc. 3-79, under drought stress by withdrawing water at flowering and boll stage. Results showed that the basic drought response in cotton included a series of broad-spectrum responses, such as amino acid synthesis, hormone (abscisic acid, ABA) signal transduction, and mitogen-activated protein kinases signal transduction pathway, which activated in both drought-tolerant and drought-sensitive lines. However, the difference of their imported fragments and diminished sequences triggers endoplasmic reticulum (ER) protein processing, photosynthetic-related pathways (in leaves), and membrane solute transport (in roots) in drought-tolerant line T307, while these are missed or not activated in drought-sensitive line S48, reflecting the different drought tolerance of the two genotypes. Virus-induced gene silencing assay of drought-tolerant differentially expressed heat shock protein (HSP) genes (mainly in leaf) and ATP-binding cassette (ABC) transporter genes (mainly in roots) indicated that those genes play important role in cotton drought tolerant. Combined analysis of transcriptomics and metabolomics highlighted the important roles of ER-stress-related HSP genes and root-specific ABC transporter genes in plants drought tolerance. These results provide new insights into the molecular mechanisms underlying the drought stress adaptation in cotton.

Reproductive Stage Drought Tolerance in Wheat: Importance of Stomatal Conductance and Plant Growth Regulators.

Drought stress requires plants to adjust their water balance to maintain tissue water levels. Isohydric plants (‘water-savers’) typically achieve this through stomatal closure, while anisohydric plants (‘water-wasters’) use osmotic adjustment and maintain stomatal conductance. Isohydry or anisohydry allows plant species to adapt to different environments. In this paper we show that both mechanisms occur in bread wheat (Triticum aestivum L.). Wheat lines with reproductive drought-tolerance delay stomatal closure and are temporarily anisohydric, before closing stomata and become isohydric at higher threshold levels of drought stress. Drought-sensitive wheat is isohydric from the start of the drought treatment. The capacity of the drought-tolerant line to maintain stomatal conductance correlates with repression of ABA synthesis in spikes and flag leaves. Gene expression profiling revealed major differences in the drought response in spikes and flag leaves of both wheat lines. While the isohydric drought-sensitive line enters a passive growth mode (arrest of photosynthesis, protein translation), the tolerant line mounts a stronger stress defence response (ROS protection, LEA proteins, cuticle synthesis). The drought response of the tolerant line is characterised by a strong response in the spike, displaying enrichment of genes involved in auxin, cytokinin and ethylene metabolism/signalling. While isohydry may offer advantages for longer term drought stress, anisohydry may be more beneficial when drought stress occurs during the critical stages of wheat spike development, ultimately improving grain yield.

Bulk analysis by resequencing and RNA-seq identifies candidate genes for maintaining leaf water content under water deficit in maize.

Drought is one of the main abiotic stresses adversely affecting maize growth and grain yield. Identifying drought tolerance-related genes and breeding varieties with enhanced tolerance are effective strategies for minimizing the effects of drought stress. In this study, the leaf relative water content (LRWC) was used for evaluating drought tolerance. QTL-seq analysis of 419 F2 individuals from a cross between ZhengT22 (the drought-tolerant line with high LRWC) and ZhengA88 (the drought-sensitive line with low LRWC) revealed four LRWC-related QTLs (qLRWC2, qLRWC10a, qLRWC10b, and qLRWC10c) in maize seedlings under water deficit. Of these QTLs, qLRWC2 was located in a 2.03-Mb interval on chromosome 2, whereas qLRWC10a, qLRWC10b, and qLRWC10c were located in 2.85-, 3.99-, and 2.05-Mb intervals, respectively, on chromosome 10, and the 93 genes contained the variation loci locating in the four QTLs regions. To identify the candidate genes within the QTLs, an RNA-seq analysis was performed for the parents exposed to water deficit. Seven genes with effective variation loci showed significant difference in expression either in ZhengA88 or ZhengT22 in response to water deficit. Moreover, among the genes, ZmPrx64, ZmCIPK, HSP90, and ABCG34 have all been shown to be related to water stress in the previous studies. Thus, they are primary considered as the potential candidate genes controlling LRWC under water deficit at the seeding stage of maize in this study. These findings will help clarify the molecular basis of drought tolerance in maize seedlings and may be relevant for future functional analysis and for breeding drought-tolerant maize varieties.

Genome-wide identification and comparative analysis of drought related genes in roots of two maize inbred lines with contrasting drought tolerance by RNA sequencing

Drought is one of the most important abiotic stresses affecting maize growth and development and therefore resulting in yield loss. Thus it is essential to understand molecular mechanisms of drought stress responses in maize for drought tolerance improvement. The root plays a critical role in plants sensing water deficit. In the present study, two maize inbred lines, H082183, a drought-tolerant line, and Lv28, a drought-sensitive line, were grown in the field and treated with different water conditions (moderate drought, severe drought, and well-watered conditions) during vegetative stage. The transcriptomes of their roots were investigated by RNA sequencing. There were 1 428 and 512 drought-responsive genes (DRGs) in Lv28, 688 and 3 363 DRGs in H082183 under moderate drought and severe drought, respectively. A total of 31 Gene Ontology (GO) terms were significantly over-represented in the two lines, 13 of which were enriched only in the DRGs of H082183. Based on results of Kyoto encyclopedia of genes and genomes (KEGG) enrichment analysis, “plant hormone signal transduction” and “starch and sucrose metabolism” were enriched in both of the two lines, while “phenylpropanoid biosynthesis” was only enriched in H082183. Further analysis revealed the different expression patterns of genes related to abscisic acid (ABA) signal pathway, trehalose biosynthesis, reactive oxygen scavenging, and transcription factors might contribute to drought tolerance in maize. Our results contribute to illustrating drought-responsive molecular mechanisms and providing gene resources for maize drought improvement.

干旱胁迫对玉米叶片光合特性和穗发育特征的影响

PDF HTML阅读 XML下载 导出引用 引用提醒 干旱胁迫对玉米叶片光合特性和穗发育特征的影响 DOI: 10.5846/stxb201811022371 作者: 作者单位: 作者简介: 通讯作者: 中图分类号: 基金项目: 作物生物学国家重点实验室开放课题（2019KF03）；农业部商丘农业环境科学观测实验站开放课题（FIRI2019-02-0103）；国家"十三五国家重点研发计划"（2016YFD0100503） Effects of drought on photosynthesis and ear development characteristics of maize Author: Affiliation: Fund Project: 摘要 | 图/表 | 访问统计 | 参考文献 | 相似文献 | 引证文献 | 资源附件 | 文章评论 摘要:玉米是需水量较大的粮食作物之一，拔节至开花的穗期是其一生中的需水临界期，研究玉米穗期对干旱胁迫的响应机制对提高玉米干旱适应性具有重要意义。以筛选后的干旱敏感自交系PH6WC （6WC）和抗旱自交系郑58（Z58）为试验材料，采用测坑控水试验，于穗期设置3个水分处理（正常灌水CK、轻度干旱LD、中度干旱MD），研究了穗期不同水分处理对雌雄穗发育特性、开花吐丝间隔以及穗位叶光合特性的影响。结果表明：LD对Z58的株高、雄穗生长特性、叶绿素相对含量和光系统II最大光化学效率没有显著影响，但雌穗长显著降低；MD显著降低了Z58的穗位叶光合特性、雌雄穗的穗长和干物质积累。对于6WC，LD抑制了其植株生长和穗的发育，使雌穗长、雌穗直径、雄穗长、干物质向穗的分配比率、穗位叶的叶绿素a、叶绿素b和光合性能综合指数（PIABS）分别降低了35.3%、11.8%、20.6%、25%、21.1%、20%、23.8%；干旱胁迫程度越重对6WC雌雄穗的发育影响越大。此外，LD与MD分别延长6WC的开花吐丝间隔期（ASI）至5天、9天，LD和MD分别延长Z58的ASI 0、3天。综上所述：穗期的干旱胁迫在不同程度上影响了6WC和Z58穗位叶的光合特性，但是对干旱敏感自交系6WC雌雄穗的生长发育的抑制显著高于Z58，以至于降低了干物质向穗部的积累与分配。 Abstract:Maize is one of the grain crops with a large demand of water. Its ear period from jointing stage to anthesis stage is the critical period of its life. It is significant meaningful to study the response mechanism of ear stage to drought stress for improving drought adaptability of maize. In this paper, drought sensitive inbred line PH6WC (6WC) and drought-resistant inbred line Zheng 58 (Z58) were selected as experimental materials. Water control experiment was performed in the pit, and three water treatments (normal irrigation CK, mild drought LD, and moderate drought MD) were set up at ear period, drought treatment would recover to the normal water level after anthesis stage. The ear and tassel development characteristics, anthesis-silking interval (ASI), and the influence of ear leaf photosynthetic characteristics were measured under different water treatments. The results showed that LD didn't significantly affect plant height, growth characteristics of ear, relative content of chlorophyll, and maximum photochemical efficiency of PSII in Z58, but significantly decreased the length of ear. MD significantly reduced photosynthetic characteristics, ear length and dry matter accumulation of both ear and tassel in Z58. As for 6WC, LD inhibited the growth of plant and the development of ear, reduced the length and diameter of ear, length of tassel, distribution ratio of dry matter to ear, the content of chlorophyll a and b, and composite index of photosynthetic performance (PIABS) by 35.3%, 11.8%, 20.6%, 25.0%, 21.1%, 20.0% and 23.8%, respectively. The higher the degree of drought stress was, the greater the influence on the development of 6WC ear was. In addition, LD and MD resulted in 5 and 9 days' delay in ASI of 6WC, respectively; LD and MD resulted in 0 and 3 days' delay in ASI of Z58, respectively. To sum up, the drought stress at ear stage affected the photosynthesis characteristics of 6WC and Z58 to different degrees, furtherly the growth and development of ear and tassel of the drought sensitive inbred line was inhibited significantly more than that of the drought-resistant inbred line, which reduced the accumulation and distribution of dry matter to ear. 参考文献 相似文献 引证文献

Transcriptome and GWAS analyses reveal candidate gene for seminal root length of maize seedlings under drought stress

Water deficits are a major constraint on maize growth and yield, and deep roots are one of the major mechanisms of drought tolerance. In this study, four root and shoot traits were evaluated within an association panel consisting of 209 diverse maize accessions under well-watered (WW) and water-stressed (WS) conditions. A significant positive correlation was observed between seminal root length (SRL) under WS treatment and the drought tolerance index (DI) of maize seedlings. The transcriptome profiles of maize seminal roots were compared between four drought-tolerant lines and four drought-sensitive lines under both water conditions to identify genes associated with the drought stress response. After drought stress, 343 and 177 common differentially expressed genes (DEGs) were identified in the drought-tolerant group and drought-sensitive group, respectively. In parallel, a coexpression network underlying SRL was constructed on the basis of transcriptome data, and 10 hub genes involved in two significant associated modules were identified. Additionally, a genome-wide association study (GWAS) of the SRL revealed 62 loci for the two water treatments. By integrating the results of the GWAS, the common DEGs and the coexpression network analysis, 7 promising candidate genes were prioritized for further research. Together, our results provide a foundation for the enhanced understanding of seminal root changes in response to drought stress in maize.

Comparative proteome analysis of drought-sensitive and drought-tolerant maize leaves under osmotic stress

Drought is a major yield-limiting factor in maize production. Osmotic stress was applied to two maize inbred lines with polyethylene glycol 6000 treatments. Proteins from the leaves were analyzed by two-dimensional gel electrophoresis and peptide mass fingerprinting at two time points, 24 and 48 h after osmotic stress. Thirty-five proteins were differentially expressed between control and treatment groups in the two maize inbred lines. In ‘Qi319’, a drought-tolerant inbred line, there were five up-regulated proteins at 24 h and 13 up-regulated and one down-regulated protein at 48 h. In drought-sensitive line ‘Zheng58’, 10 proteins were up-regulated at 24 h, while six proteins were up-regulated at 48 h. The 35 proteins were subjected to mass spectrometry and 17 proteins were successfully identified. These proteins were classified into six categories: photosynthesis-related, energy and metabolism, signaling pathways, protein synthesis, defense-related, and unclassified.

Regulatory Role of Silicon in Mediating Differential Stress Tolerance Responses in Two Contrasting Tomato Genotypes Under Osmotic Stress.

Previous studies have shown the role of silicon (Si) in mitigating the adverse effect of drought stress in different crop species. However, data are lacking on a comparison of drought tolerant and drought sensitive crop cultivars in response to Si nutrition. Therefore, the aim of this study was to elucidate the mechanism (s) by which two contrasting tomato genotypes respond to Si nutrition under osmotic stress condition. Two tomato lines contrasting in their response to drought stress were hydroponically grown under polyethylene glycol (PEG, 6000) and two regimes of Si (0 and 1.5 mM). Metabolite profiling was performed in two lines. Growth and relevant physiological parameters, and expression levels of selected genes were also measured. Si application resulted in improved osmotic stress tolerance in both drought tolerant line LA0147 and drought sensitive line FERUM. In the drought tolerant line, Si enhanced uptake of sulfur (S) and ammonium () which led to a significantly higher production of amino acids arginine, methionine, serine, and glycine. While in the drought sensitive line, Si significantly increased production of amino acids proline and GABA which further lowered the level of GSSG to GSH ratio and thus balanced the redox homeostasis under osmotic stress. The higher significant production of amino acids arginine, methionine, GABA, and proline enhanced production of free polyamines putrescine and spermidine and improved osmotic stress tolerance. Therefore, we conclude that Si distinctively regulated osmotic stress tolerance in two contrasting tomato genotypes by differential accumulation of relevant amino acids which eventually led to enhanced polyamine metabolism.

Deciphering drought-induced metabolic responses and regulation in developing maize kernels.

SummaryDrought stress conditions decrease maize growth and yield, and aggravate preharvest aflatoxin contamination. While several studies have been performed on mature kernels responding to drought stress, the metabolic profiles of developing kernels are not as well characterized, particularly in germplasm with contrasting resistance to both drought and mycotoxin contamination. Here, following screening for drought tolerance, a drought‐sensitive line, B73, and a drought‐tolerant line, Lo964, were selected and stressed beginning at 14 days after pollination. Developing kernels were sampled 7 and 14 days after drought induction (DAI) from both stressed and irrigated plants. Comparative biochemical and metabolomic analyses profiled 409 differentially accumulated metabolites. Multivariate statistics and pathway analyses showed that drought stress induced an accumulation of simple sugars and polyunsaturated fatty acids and a decrease in amines, polyamines and dipeptides in B73. Conversely, sphingolipid, sterol, phenylpropanoid and dipeptide metabolites accumulated in Lo964 under drought stress. Drought stress also resulted in the greater accumulation of reactive oxygen species (ROS) and aflatoxin in kernels of B73 in comparison with Lo964 implying a correlation in their production. Overall, field drought treatments disordered a cascade of normal metabolic programming during development of maize kernels and subsequently caused oxidative stress. The glutathione and urea cycles along with the metabolism of carbohydrates and lipids for osmoprotection, membrane maintenance and antioxidant protection were central among the drought stress responses observed in developing kernels. These results also provide novel targets to enhance host drought tolerance and disease resistance through the use of biotechnologies such as transgenics and genome editing.

A Potential Role of Flag Leaf Potassium in Conferring Tolerance to Drought-Induced Leaf Senescence in Barley.

Terminal drought stress decreases crop yields by inducing abscisic acid (ABA) and premature leaf senescence. As potassium (K) is known to interfere with ABA homeostasis we addressed the question whether there is genetic variability regarding the role of K nutrition in ABA homeostasis and drought tolerance. To compare their response to drought stress, two barley lines contrasting in drought-induced leaf senescence were grown in a pot experiment under high and low K supply for the analysis of flag leaves from the same developmental stage. Relative to the drought-sensitive line LPR, the line HPR retained more K in its flag leaves under low K supply and showed delayed flag leaf senescence under terminal drought stress. High K retention was further associated with a higher leaf water status, a higher concentration of starch and other primary carbon metabolites. With regard to ABA homeostasis, HPR accumulated less ABA but higher levels of the ABA degradation products phaseic acid (PA) and dehydro-PA. Under K deficiency this went along with higher transcript levels of ABA8′-HYDROXYLASE, encoding a key enzyme in ABA degradation. The present study provides evidence for a positive impact of the K nutritional status on ABA homeostasis and carbohydrate metabolism under drought stress. We conclude that genotypes with a high K nutritional status in the flag leaf show superior drought tolerance by promoting ABA degradation but attenuating starch degradation which delays flag leaf senescence. Flag leaf K levels may thus represent a useful trait for the selection of drought-tolerant barley cultivars.

Determination of Abscisic Acid and its Relationship to Drought Stress Based on Cowpea Varieties with Different Capability of Drought Resistance

Cowpea (Vigna unguiculata L.) is one of the most important grain legume supplying necessarily dietary proteins. Although its can tolerate drought environment, still the severe condition can limit the growth and development of this plant. Abscisic acid (ABA) has a crucial function in stress physiology, but little information is available for methods describing ABA determination in cowpea and its relationship to drought stress based on cowpea varieties with different capability of drought resistance. Here, an effectual approach based on high-performance liquid chromatography (HPLC) method was established to separate and determine the endogenous abscisic acid in cowpea and further the cowpea varieties with different capability of drought resistance were used to explore relationships between ABA content and drought stress. The results potentially provided useful reference for the cultivation of cowpea crop. Results-This method showed good liner regression (R2 = 0.9998), coupled with high stability, precision and repeatability. The endogenous ABA decreased under drought treatment and the drought sensitive line had higher ABA content than drought resistant one, suggesting ABA performs a vital function in cowpea’s response and resistance to drought stress. The studies potentially provided useful reference for the cultivation and breeding of cowpea crop.

Changes in chloroplast ultrastructure in leaves of drought-stressed maize inbred lines

Chloroplasts are commonly the site of the earliest abiotic injury visible in plant ultrastructure. In this study, six inbred lines of maize (Zea mays L.) were used to analyze changes in the ultrastructure of chloroplasts and related physiological parameters under conditions of drought stress simulated by 20% polyethylene glycol 6000 (−0.6 MPa) for two days. Chloroplasts of three maize lines proved to be more sensitive. They showed changes in the ultrastructure in response to drought, including damage of thylakoid membranes, an increase in the number and size of plastoglobuli, swelling of thylakoid membranes both stromal and granal, disorganization of the thylakoid membrane system, an obvious increase in the intrathylakoid space, and a decrease in the length-to-width ratio and area of chloroplasts. In addition, the contents of malondialdehyde increased markedly in the sensitive lines. Contrary to the sensitive lines, stable structures and shapes of chloroplasts were observed in the drought-resistant lines; it could be considered as an advantage contributing to drought tolerance in the plants. In addition, the drought index of leaf fresh mass (LMDI) in the drought-sensitive lines was ≤ 0.5, which was also associated with a lower content of leaf chlorophyll. In contrast, drought tolerance coincided with lesser growth reduction, and higher LMDI and leaf chlorophyll content.

TILLING by sequencing to identify induced mutations in stress resistance genes of peanut (Arachis hypogaea).

BackgroundTargeting Induced Local Lesions in Genomes (TILLING) is a powerful reverse genetics approach for functional genomics studies. We used high-throughput sequencing, combined with a two-dimensional pooling strategy, with either minimum read percentage with non-reference nucleotide or minimum variance multiplier as mutation prediction parameters, to detect genes related to abiotic and biotic stress resistances. In peanut, lipoxygenase genes were reported to be highly induced in mature seeds infected with Aspergillus spp., indicating their importance in plant-fungus interactions. Recent studies showed that phospholipase D (PLD) expression was elevated more quickly in drought sensitive lines than in drought tolerant lines of peanut. A newly discovered lipoxygenase (LOX) gene in peanut, along with two peanut PLD genes from previous publications were selected for TILLING. Additionally, two major allergen genes Ara h 1 and Ara h 2, and fatty acid desaturase AhFAD2, a gene which controls the ratio of oleic to linoleic acid in the seed, were also used in our study. The objectives of this research were to develop a suitable TILLING by sequencing method for this allotetraploid, and use this method to identify mutations induced in stress related genes.ResultsWe screened a peanut root cDNA library and identified three candidate LOX genes. The gene AhLOX7 was selected for TILLING due to its high expression in seeds and roots. By screening 768 M2 lines from the TILLING population, four missense mutations were identified for AhLOX7, three missense mutations were identified for AhPLD, one missense and two silent mutations were identified for Ara h 1.01, three silent and five missense mutations were identified for Ara h 1.02, one missense mutation was identified for AhFAD2B, and one silent mutation was identified for Ara h 2.02. The overall mutation frequency was 1 SNP/1,066 kb. The SNP detection frequency for single copy genes was 1 SNP/344 kb and 1 SNP/3,028 kb for multiple copy genes.ConclusionsOur TILLING by sequencing approach is efficient to identify mutations in single and multi-copy genes. The mutations identified in our study can be used to further study gene function and have potential usefulness in breeding programs.Electronic supplementary materialThe online version of this article (doi:10.1186/s12864-015-1348-0) contains supplementary material, which is available to authorized users.

Differential response of root proteome to drought stress in drought sensitive and tolerant sunflower inbred lines.

Productivity of sunflower (Helianthus annuus L.), the fourth most important oilseed crop, is strongly dependent on water availability. To search for genetic variation in the ability of roots to grow into drying soil, 16 sunflower lines were screened in 2 years field experiments by imposing drought stress at flowering stage. The results differentiated RGK 21 and BGK 329 as the most sensitive and tolerant lines respectively. The time course physiological assay of these lines at seedling stage revealed roots as the most affected organ 6 days after imposing drought stress. A proteomics approach was adapted for investigating of differential changes in roots proteome under contrasting moisture regimes. Protein spots with significant changes in protein abundance were identified by nano LC-MS/MS. The results indicated that under drought stress relative abundance of metabolism related proteins were decreased in both sensitive and tolerant lines. Abundance of energy and disease/defence related proteins were decreased in the sensitive but increased in the tolerant line. The results indicate that changes in energy usage, water transport and ROS scavenging are important mechanisms for maintaining root growth as the soil dries.

Comparative proteome analysis of drought-sensitive and drought-tolerant rapeseed roots and their hybrid F1 line under drought stress

Rapeseed (Brassica napus L.), which is the third leading source of vegetable oil, is sensitive to drought stress during the early vegetative growth stage. To investigate the initial response of rapeseed to drought stress, changes in the protein expression profiles of drought-sensitive (RGS-003) and drought-tolerant lines (SLM-003), and their F1 hybrid, were analyzed using a proteomics approach. Seven-day-old rapeseed seedlings were treated with drought stress by restricting water for 7 days, and proteins were extracted from roots and separated by two-dimensional polyacrylamide gel electrophoresis. In the sensitive rapeseed line, 35 protein spots were differentially expressed under drought stress, and proteins related to metabolism, energy, disease/defense, and transport were decreased. In the tolerant line, 32 protein spots were differentially expressed under drought stress, and proteins involved in metabolism, disease/defense, and transport were increased, while energy-related proteins were decreased. Six protein spots in F1 hybrid were common among expressed proteins in the drought-sensitive and -tolerant lines. Notably, tubulin beta-2 and heat shock protein 70 were decreased in the drought-sensitive line and hybrid F1 plants, while jasmonate-inducible protein and 20S proteasome subunit PAF1 were increased in the F1 hybrids and drought-tolerant line. These results indicate that (1) V-type H(+) ATPase, plasma-membrane associated cation-binding protein, HSP 90, and elongation factor EF-2 have a role in the drought tolerance of rapeseed; (2) The decreased levels of heat shock protein 70 and tubulin beta-2 in the drought-sensitive and hybrid F1 lines might explain the reduced growth of these lines in drought conditions.

Morpho-Physiological Screening of Sunflower Inbred Lines under Drought Stress Condition

Efficiency of morphological and physiological characteristics was studied for screening of sunflower (Helianthus annuus L.) inbred lines for drought tolerance in flowering stage using principle component analysis. Sixteen sunflower inbred lines were evaluated under rainout shelter for two years. According to the results stress tolerance index and stress susceptibility index each had more efficiency for identifying of drought tolerant and sensitive lines respectively. Principle component analysis was emerged as a powerful method for identifying of drought tolerant and sensitive lines which separated BGK 329 and RGK 21 as the most drought tolerant and sensitive lines respectively in the reverse direction of its biplot. The tolerant line was differentiated principally by higher plant height, stem and head diameter, seed weight, seed number, root and shoot dry weight, root length, leaf area, osmotic adjustment, Fv/Fm, SPAD value and seed yield and lower leaf temperature and specific leaf area compared to the sensitive line. Plant height, stem and head diameter were identified as morphological and leaf area, leaf temperature, Fv/Fm and SPAD value as efficient, none destructive physiological indicators for screening of sunflower genotypes under drought stress condition.

Morpho-physiological changes in maize seedling sunder osmotic stress

Drought is a major abiotic stress factor limiting crop growth, development and production worldwide. The objective of this study was to evaluate tolerance to osmotic stress of maize seedlings. More than 6,000 accessions from the Maize Research Institute gene bank were tested under controlled drought (at flowering) in Egypt, and afterwards in temperate climate (Serbia and Macedonia). Out of 41 drought tolerant accessions in the field, five inbred lines were chosen for laboratory testing, as well as one drought sensitive line. These genotypes were exposed to 4% polyethylene glycol-PEG (Mr 10000) for 24 h and 48 h. Nine-day-old seedlings compared to control conditions were analyzed in root and shoot length, fresh and dry weight and proline content. Results showed reduction in all parameters under stress, while only proline content increased in all PEG treated genotypes compared to control.