Heterogeneous expression of stearoyl-acyl carrier protein desaturase genes SAD1 and SAD2 from Linum usitatissimum enhances seed oleic acid accumulation and seedling cold and drought tolerance in Brassica napus

Flax(Linum usitatissimum L.)is a versatile crop and its seeds are a major source of unsaturated fatty acids.Stearoyl-acyl carrier protein desaturase(SAD)is a dehydrogenase enzyme that plays a key role in oleic acid biosynthesis as well as responses to biotic and abiotic stresses.However,the function of SAD orthologs from L.usitatissimum has not been assessed.Here,we found that two LuSAD genes,LuSAD1 and LuSAD2,are present in the genome of L.usitatissimum cultivar‘Longya 10’.Heterogeneous expression of either LuSAD1 or LuSAD2 in Arabidopsis thaliana resulted in higher contents of total fatty acids and oleic acid in the seeds.Interestingly,ectopic expression of LuSAD2 in A.thaliana caused altered plant architecture.Similarly,the overexpression of either LuSAD1 or LuSAD2 in Brassica napus also resulted in increased contents of total fatty acids and oleic acid in the seeds.Furthermore,we demonstrated that either LuSAD1 or LuSAD2 enhances seedling resistance to cold and drought stresses by improving antioxidant enzyme activity and nonenzymatic antioxidant levels,as well as reducing membrane damage.These findings not only broaden our knowledge of the LuSAD functions in plants,but also offer promising targets for improving the quantity and quality of oil,and the abiotic stress tolerance of oil-producing crops,through molecular manipulation.

Leaf Morphology Genes SRL1 and RENL1 Co-Regulate Cellulose Synthesis and Affect Rice Drought Tolerance

The morphological development of rice(Oryza sativa L.)leaves is closely related to plant architecture,physiological activities,and resistance.However,it is unclear whether there is a co-regulatory relationship between the morphological development of leaves and adaptation to drought environment.In this study,a drought-sensitive,roll-enhanced,and narrow-leaf mutant(renl1)was induced from a semi-rolled leaf mutant(srl1)by ethyl methane sulfonate(EMS),which was obtained from Nipponbare(NPB)through EMS.Map-based cloning and functional validation showed that RENL1 encodes a cellulose synthase,allelic to NRL1/OsCLSD4.The RENL1 mutation resulted in reduced vascular bundles,vesicular cells,cellulose,and hemicellulose contents in cell walls,diminishing the water-holding capacity of leaves.In addition,the root system of the renl1 mutant was poorly developed and its ability to scavenge reactive oxygen species(ROS)was decreased,leading to an increase in ROS after drought stress.Meanwhile,genetic results showed that RENL1 and SRL1 synergistically regulated cell wall components.Our results revealed a theoretical basis for further elucidating the molecular regulation mechanism of cellulose on rice drought tolerance,and provided a new genetic resource for enhancing the synergistic regulation network of plant type and stress resistance,thereby realizing simultaneous improvement of multiple traits in rice.

Assessment of molecular markers and marker-assisted selection for drought tolerance in barley(Hordeum vulgare L.)

This review updates the present status of the field of molecular markers and marker-assisted selection(MAS),using the example of drought tolerance in barley.The accuracy of selected quantitative trait loci(QTLs),candidate genes and suggested markers was assessed in the barley genome cv.Morex.Six common strategies are described for molecular marker development,candidate gene identification and verification,and their possible applications in MAS to improve the grain yield and yield components in barley under drought stress.These strategies are based on the following five principles:(1)Molecular markers are designated as genomic‘tags’,and their‘prediction’is strongly dependent on their distance from a candidate gene on genetic or physical maps;(2)plants react differently under favourable and stressful conditions or depending on their stage of development;(3)each candidate gene must be verified by confirming its expression in the relevant conditions,e.g.,drought;(4)the molecular marker identified must be validated for MAS for tolerance to drought stress and improved grain yield;and(5)the small number of molecular markers realized for MAS in breeding,from among the many studies targeting candidate genes,can be explained by the complex nature of drought stress,and multiple stress-responsive genes in each barley genotype that are expressed differentially depending on many other factors.

Overexpression of the peroxidase gene ZmPRX1 increases maize seedling drought tolerance by promoting root development and lignification

Drought is a main abiotic stress factor hindering plant growth,development,and crop productivity.Therefore,it is crucial to understand the mechanisms by which plants cope with drought stress.Here,the function of the maize peroxidase gene ZmPRX1 in drought stress tolerance was investigated by measurement of its expression in response to drought treatment both in a ZmPRX1 overexpression line and a mutant line.The higher root lignin accumulation and seedling survival rate of the overexpression line than that of the wild type or mutant support a role for ZmPRX1 in maize drought tolerance by regulating root development and lignification.Additionally,yeast one-hybrid,Dule luciferase and ChIP-qPCR assays showed that ZmPRX1 is negatively regulated by a nuclear-localized ZmWRKY86 transcription factor.The gene could potentially be used for breeding of drought-tolerant cultivars.

Selection of Cowpea [(Vigna unguiculata (L.) WALP] Genotypes for Drought Tolerance Using Selection Indices

Cowpea [(Vigna unguiculata (L.)] is one of the most important arid legumes cultivated for pulse and forage production. However, in cowpea, not much is known about the base index selection method in breeding for drought tolerance. Consequently, the present study has been conducted to: 1) evaluate the yield performance of cowpea genotypes under artificial drought and well-watered condition;2) develop a base index using multiple traits for ranking genotype performance. The experiment was a 25 × 2 factorial laid out in a Randomized Complete Block Design (RCBD) with three replications. The experiment was carried out in the screen house at the Department of Horticulture at KNUST. The result showed that KPR1-96-73, Simbo, CZ06-4-16, Wilibaly and Agyenkwa were high yielding in well-water condition while Ghana Shoba, Sangaraka, NKetewade, Ghana-Shoni and Korobalen were high yielding genotypes in water stress condition. The average yield reduction was 60.6% for grain respectively. The biplot displays revealed four groups among the genotypes tested which was based on their yielding capacity and drought tolerance. In cluster B high yielding and drought tolerant genotypes were identified, high yielding and drought susceptible have been identified in cluster A, low yielding and drought tolerant in cluster D, and lastly low yielding and drought susceptible in cluster C. Genotypes in cluster B, were the best due to the fact that it combines high yield and tolerance to drought. They were Ghana Shoni, Nketewade, Sangaraka and Ghana shoba. These genotypes might be suitably employed in further drought tolerance breeding program of cowpea.

Identification of Drought Tolerance in Peanut (Arachis hypogaea) Germplasm at Seedling Stage

[Objective] This study was conducted to identify the drought tolerance of peanut（Arachis hypogaea） seedlings. [Method] The plant height, fresh weight and dry weight of 80 peanut varieties or lines were determined under the drought stress simulated using 15% PEG6000 in laboratory. Relative values of the three indices were calculated to measure the drought tolerance of the 80 peanut varieties or lines. [Result] The growth of peanut seedlings was significantly inhibited after 10 d of drought treatment. Cluster analysis revealed that at Euclidean distance D=15, the80 peanut varieties or lines were divided into four categories A, B, C and D. Among them, category B had better drought tolerance while category C was sensitive to drought. In all the four categories, the approved peanut varieties or lines showed better drought tolerance than the unapproved ones. [Conclusion] The drought tolerant and the drought sensitive peanut varieties or lines screened in this study can be used for further basic research and germplasm improvement.

Grey Correlation Analysis of Physiological Traits Related to Drought Tolerance in Pennisetum sp.

The drought resistance of Pennisetum sp. was analyzed under different drought stress conditions simulated by various concentrations of PEG-6000. Changesofa series of indexes such as chlorophyll content, water content, relative electrical conductivity of osmotic solution, MDA content, proline content, soluble polysaccharide content and soluble protein content in the leaves were measured.The correlation of these indexes with the drought resistance of Pennisetum sp. was an- alyzed by the method of grey correlation analysis. The results showed that the chlorophyll, water content, relative electrical conductivity and soluble protein con- tentexhibited obvious negative correlation with the stress concentration, which de- creasedfollowing the increase of PEG-6000 concentration. The soluble polysaccha- ride contentshowed an increasing trend,the MDA content showed a rise at first fol- lowed by a declinetrend, while the prolinecontent was just opposite to MDA. The changes of the 3 indexes showed obvious positive correlation with thestress con- centration. The correlation of these indexes with the drought resistance of Pennise- tum sp. were ranked as follows： leaf water content （0.980 8）, chlorophyll content （0.967 9）, MDA content （0.876 0）, soluble polysaccharide content （0.839 5）, soluble protein content（0.827 5）, relative electrical conductivity of osmotic solution（0.670 8）, and proline content（0.571 3）.

Comprehensive Evaluation on Drought Tolerance of Widely-used Rice Varieties with Subordinate Function Method

Using drought-tolerant cultivar IAPAR 9 （upland rice from Brazil） and drought-sensitive varieties IR64 as the controls, the drought tolerances of total 26 rice varieties widely used in production were evaluated with subordinate function method based on morphological, physiological and yield traits. The results showed that the trait values of grain yield per plant （GYP）, effective panicles per plant （EPP）, seed-setting rate （SSR）, panicle length （PL）, leaf relative water content （RWC） and chlorophyll content （SPAD） in all tested varieties decreased significantly under the conditions of drought stress. The subordinate function values of these traits of all tested rice varieties were thus calculated varieties. Based on the aver- age subordinate function values of all these traits, total 7 （i.e. Y Liangyou 1） and 3 （i.e. Liangyou Peijiu） rice varieties were identified as drought-tolerant and drought- sensitive varieties, respectively.

Physiological Mechanism for Anthocyanins to Strengthen the Drought Tolerance of Plants

This paper summarized the possible physiological mechanism by which anthocyanins strengthen the tolerance of plants to drought. Drought stress can in-duce plant cel s to synthesize and accumulate anthocyanins. The photochemical properties, subcel ular accumulation sites and spatial distributions in plant organs and tissues of anthocyanins determine their function of strengthening plant tolerance, which is realized by three possible physiological mechanisms： （1） anthocyanins and their chelated metal ions can optimize the osmoregulation ability of the plant cel s by directly acting as the osmoregulation substances of the cel s, （2） anthocyanins with suitable spatial locations can reduce the photoinhibition of the plants under drought stresses, （3） anthocyanins can effectively maintain and improve the active oxygen-scavenging capacity of the plant cel s under drought conditions. Therein, that the anthocyanins enhance the antioxidant capacity of the plant cel s under drought stresses is probably the main reason for the anthocyanins to strengthen the drought tolerance of plants. This review could provide a reference for the mechanism re-search of the drought resistance and the breeding of the drought-resistant cultivars for the plants holding the ability to synthesize and accumulate anthocyanins.

Analysis on Drought Tolerance of TaPIMP1 Transgenic Wheat

[Objective] This study aimed to evaluate the application potential of wheat MYB protein-encoding gene TaPIMP1 in the breeding of drought-tolerant wheat germplasm. [Method] The homozygous transgenic lines with TaPIMP1 gene which is driven by ubiquitin promoter and their recipient Yangmai 158 were cultivated under simulated drought condition. Then, seed germination, seedling growth, and some biochemical parameters associated with abiotic stress of the three cultivars were an- alyzed. [Result] In the medium containing 20% PEG6000, the expression level of TaPIMP1 gene in all the three wheat cultivars changed greatly within the first 24 h; the seed germination rate, the lengths of coleoptile and radical of two transgenic lines B64 and B208 were significantly higher than those of control Yangmai 158. In the medium containing 10%-20% PEG6000, the leaf relative water content and sol- uble sugar contents of two TaPIMP1 transgenic lines were significantly higher than those in control. In the medium containing 15%-20% PEG6000, the MDA content of two transgenic lines was significantly lower than that of the control. [Conclusion] The drought tolerance of the two transgenic lines has been improved obviously com- pared with Yangmai 158, so the TaPIMP1 gene can be introduced to develop new drought-tolerant wheat cultivars.

Analysis of Combining Ability of Drought Tolerance in Maize

By using complete-diallel cross design（Griffing method I）, the influence of the combination of different high-yield genotypes of maize on the drought tolerance of their offspring, the general combining ability, the specific combining ability and the back cross effect of drought tolerance between parents and the main genetic parameters for drought tolerance were analyzed. The result indicated that there were significant differences in general combining ability effects（GCA） of maize; there were highly significant differences in special combining ability effects（SCA）; there was no significant difference in reciprocal effects（R）. There were apparent differences in drought tolerance among six parents; to be specific, Zheng 58 had the highest drought tolerance, while PH4CV had the lowest. Improving drought-tolerant parents with Zheng 58, Ji 853 and Xinzi 8717 had gain superiority effects on the increase of drought tolerance in offspring. The influence of the genetic additive effect on the drought tolerance of offsprings varied with different parents and combinations. Therefore, the expression of drought tolerance inheritance genes was determined only by the additive and non-additive genetic effects but had little relationship with reciprocal effects. The selection of drought tolerance of maize should be conducted at higher generations.

Evaluation of Chlorophyll Content and Fluorescence Parameters as Indicators of Drought Tolerance in Barley

Drought is a major abiotic stress that severely affects food production worldwide. Agronomic and physiological traits associated with drought tolerance are suitable indicators for selection of drought tolerance genotypes to reduce the impact of water deficit on crop yield in breeding program. The objective of this study was to identify indicators related to drought tolerance through analysis of photosynthetic traits in barley （Hordeum vulgare L.）. These traits included chlorophyll content, initial fluorescence （Fo）, maximum primary yield of photochemistry of photosystem Ⅱ （Fv /Fo） and maximum quantum yield of photosystem Ⅱ （Fv/Fm）. Four genotypes （Tadmor, Arta, Morocco9-75 and WI2291） variable in drought tolerance were used to investigate the correlation between these traits and drought tolerance. The results reflected that all of these traits were affected negatively in the four genotypes at different levels of post-anthesis drought stress, but the decrease in drought tolerant genotypes was much less than that of drought sensitive genotypes. The results further revealed that the components of the photosynthetic apparatus could be damaged significantly in drought sensitive genotypes, while drought tolerant genotypes were relatively less affected. On the other hand, the values of chlorophyll content, Fo, Fv/Fo and Fv/Fm in drought tolerance genotypes were significantly higher than those in drought sensitive genotypes under drought stress. It was concluded that chlorophyll content, Fo, Fv/Fo and Fv/Fm could be considered as reliable indicators in screening barley germplasm for drought tolerance.

QTL Mapping for Drought Tolerance at Stages of Germination and Seedling in Wheat (Triticum aestivum L.) Using a DH Population

Drought is a major constraint in many wheat( Triticum aestivum L.) production regions. Quantitative trait loci (QTLs) conditioning drought tolerance at stages of germination and seedling in wheat were identified in a double haploid (DH) population derived from the cross, Hanxuan10×Lumai14, using amplified fragment length polymorphism (AFLP) and simple sequence repeat (SSR) markers. Interval mapping analysis revealed that QTLs for drought tolerance at germination stage were located on chromosomes 1B, 2B, 5A, 6B, 7A and 7B, respectively, and the most effective QTL was mapped on chromosome 2B, explaining 27.2% of phenotypic variance. The QTLs for drought tolerance at seedling stage were located on 1B, 3B and 7B, respectively, and the most effective QTL was mapped on chromosome 3B, explaining 21.6% of phenotypic variance. Their positions were different from those of QTLs conferring drought tolerance at germination stage, indicating that drought tolerance at germination stage and seedling stage was controlled by different loci. Most of the identified QTLs explained 18% or more of phenotypic variance for drought tolerance at germination and seedling stage, and would be useful in future for marker assisted selection programs and cultivar improvement.

Breeding wheat for drought tolerance： Progress and technologies

Recurrent drought associated with climate change is among the principal constraints to global productivity of wheat（Triticum aestivum（L.） and T. turgidum（L.））. Numerous efforts to mitigate drought through breeding resilient varieties are underway across the world. Progress is, however, hampered because drought tolerance is a complex trait that is controlled by many genes and its full expression is affected by the environment. Furthermore, wheat has a structurally intricate and large genome. Consequently, breeding for drought tolerance requires the integration of various knowledge systems and methodologies from multiple disciplines in plant sciences. This review summarizes the progress made in dry land wheat improvement, advances in knowledge, complementary methodologies, and perspectives towards breeding for drought tolerance in the crop to create a coherent overview. Phenotypic, biochemical and genomics-assisted selection methodologies are discussed as leading research components used to exploit genetic variation. Advances in phenomic and genomic technologies are highlighted as options to circumvent existing bottlenecks in phenotypic and genomic selection, and gene transfer. The prospects of further integration of these technologies with other omics technologies are also provided.

Effects of Root Pruning on Non-Hydraulic Root-Sourced Signal, Drought Tolerance and Water Use Efficiency of Winter Wheat

Two pot experiments were conducted to study the effects of root pruning at the stem elongation stage on non-hydraulic root-sourced signals （nHRS）, drought tolerance and water use efficiency of winter wheat （Triticum aestivum）. The root pruning significantly reduced the root weight of wheat, but had no effect on root/shoot ratio at the two tested stages. At booting stage, specific root respiration of root pruned plants was significantly higher than those with intact roots （1.06 and 0.94 mmol g-1 s-1, respectively）. The soil water content （SWC） at which nHRS for root pruned plants appeared was higher and terminated lower than for intact root plants, the threshold range of nHRS was markedly greater for root pruned plants （61.1-44.6% field water capacity） than for intact root plants （57.9-46.1% field water capacity）. At flowering stage, while there was no significant difference in specific root respiration. The SWCs at which nHRS appeared and terminated were both higher for root pruned plants than for intact root plants. The values of chlorophyll fluorescence parameters, i.e., the effective photosystem II quantum yield （F PS II ）, the maximum photochemical efficiency of PS II （F v /F m ）, coefficient of photochemical quenching （qP）, and coefficient of non-photochemical quenching （NPQ）, in root pruned plants were significantly higher than in intact root plants, 7 d after withholding of water. Root pruned plants had significantly higher water use efficiency （WUE） than intact root plants in well-watered and medium drought soil, but not in severe drought condition. In addition, root pruning had no significant effect on grain yield in well-watered and medium drought soil, but significantly decreased grain yield in severe drought condition. In conclusion, the current study showed that root pruning significantly altered nHRS sensitivity and improved WUE of winter wheat in well-watered and medium drought soil, but lowered drought tolerance of winter wheat in severe drought soil. This suggests a possible direction of drought- resistance breeding and potential agricultural measure to improve WUE of winter wheat under semiarid conditions.

Mapping of QTL Associated with Drought Tolerance in a Semi-Automobile Rain Shelter in Maize (Zea mays L.)

Drought is a major constraint in maize production worldwide. We studied quantitative trait loci （QTL） underlying drought tolerance for maize plants grown in two different environments. Traits investigated included ASI, plant height, grain yield, ear height, and ear setting. A genetic linkage map was constructed with 120 simple sequence repeat （SSR） markers based on an F2 population derived from a cross between D5 （resistant parent） and 7924 （susceptible parent）. Correlation and heritability were calculated. QTLs of these traits were identified by composite interval mapping combined with a linkage map covering 1 790.3 cM. The markers were arranged in ten linkage groups. QTL mapping was made of the mean trait performance of the 180 F2：3 population. The results showed five, five, six, four, and five QTLs for ASI, plant height, grain yield, ear height, and ear setting under full irrigation condition, respectively, and four, seven, six, four, and four QTLs for ASI, plant height, grain yield, ear height, and ear setting under severe late stress conditions, respectively. Especially the four QTLs detected for five traits in 2008 and 2009. The universal QTLs information generated in this study will aid in undertaking an integrated breeding strategy for further genetic studies in drought tolerance improvement in maize.

QTL mapping of drought tolerance traits in soybean with SLAF sequencing

Drought stress is an important factor affecting soybean yield.Improving drought tolerance of soybean varieties can increase yield and yield stability when the stress occurs.Identifying QTL related to drought tolerance using molecular marker-assisted selection is able to facilitate the development of drought-tolerant soybean varieties.In this study,we used a high-yielding and drought-sensitive cultivar‘Zhonghuang 35’and a drought-tolerant cultivar‘Jindou 21’to establish F6:9 recombinant inbred lines.We constructed a highdensity genetic map using specific locus amplified fragment sequencing(SLAF-Seq)technology.The genetic map contained 8078 SLAF markers distributing across 20 soybean chromosomes with a total genetic distance of 3780.98 c M and an average genetic distance of0.59 c M between adjacent markers.Two treatments(irrigation and drought)were used in the field tests,the Additive-Inclusive Composite Interval Mapping(ICIM-ADD)was used to call QTL,and plant height and seed weight per plant were used as the indicators of drought tolerance.We identified a total of 23 QTL related to drought tolerance.Among them,seven QTL(q PH2,q PH6,q PH7,q PH17,q PH19-1,q PH19-2,and q PH19-3)on chromosomes 2,6,7,17,and 19 were related to plant height,and five QTL(q SWPP2,q SWPP6,q SWPP13,q SWPP17,and q SWPP19)on chromosomes 2,6,13,17,and 19 were related to seed weight and could be considered as the major QTL.In addition,three common QTL(q PH6/q SWPP6,q PH17/q SWPP17,and q PH19-3/q SWPP19)for both plant height and seed weight per plant were located in the same genomic regions on the same chromosomes.Three(q PH2,q PH17,and q PH19-2)and four novel QTL(q SWPP2,q SWPP13,q SWPP17,and q SWPP19)were identified for plant height and seed weight per plant,respectively.Two pairs of QTL(q PH2/q SWPP2 and q PH17/q SWPP17)were also common for both plant height and seed weight per plant.These QTL and closely linked SLAF markers could be used to accelerate breeding for drought tolerant cultivars via MAS.

Improvement of Drought Tolerance in Transgenic Tobacco Plants by a Dehydrin-Like Gene Transfer

A full-length cDNA of dehydrin BcDh2 from Boea crassifolia and its antisense nucleotidesequence have been transferred into tobacco (Nicotiana tabacum) NC89 under the controlof a caulifower mosaic virus 35S promoter. Under a progressive water stress, photosyntheticrate, transpiration rate and stomatal conductance of the sense and antisense plantsreduced, and those of the control reduced much more. Photosynthetic rate, transpirationrate and stomatal conductance of all plants tested increased significantly 24 hourslater after recoveried water supply, and those of the sense and antisense plants werehigher than control. These indicated that overexpression of a dehydrin gene in tobaccomay improve tolerance to water stress for plants, however, antisense BcDh2 gene intransgenic plant did not influence physiological conditions. The results of germinationexperiment of the transgenic seeds showed that on MS medium with different concentrationPEG (8000), sense seed could more endure drought than control, while antisense seed wassensitive to drought. The results suggested that the overexpression of a dehydrin genein tobacco might improve the tolerance to water stress for plants.

Analysis of drought tolerance and genetic and epigenetic variations in a somatic hybrid between Ipomoea batatas (L.) Lam. and I. triloba L.

The somatic hybrid KT1 was previously obtained from protoplast fusion between sweetpotato （Ipomoea batatas （L.） Lam.） cv. Kokei No. 14 and its wild relative I. triloba L. However, its genetic and epigenetic variations have not been investigated. This study showed that KT1 exhibited significantly higher drought tolerance compared to the cultivated parent Kokei No. 14. The content of proline and activities of superoxide dismutase （SOD） and photosynthesis were significantly increased, while malonaldehyde （MDA） content was significantly decreased compared to Kokei No. 14 under drought stress. KT1 also showed higher expression level of well-known drought stress-responsive genes compared to Kokei No. 14 under drought stress. Amplified fragment length polymorphism （AFLP） and methylation-sensitive amplified polymorphism （MSAP） analyses indicated that KT1 had AFLP and MSAP band patterns consisting of both parent specific bands and changed bands. Fur- ther analysis demonstrated that in KT1. the proportions of Kokei No. 14 specific genome components and methylation sites were much greater than those of I. triloba. KT1 had the same chloroplast and mitochondrial genomes as Kokei No. 14. These results will aid in developing the useful genes ofI. triloba and understanding the evolution and phylogeny of the cultivated sweetpotato.

Transcriptomes of early developing tassels under drought stress reveal differential expression of genes related to drought tolerance in maize

Tassel, the male reproductive organs in maize, its development is adversely affected by drought during tasseling. To determine drought tolerance mechanisms of tassel differentiation at transcriptome level, RNA-Seq was performed using RNA of early developing tassel from 10 maize inbred lines under well-watered （control） and drought-stressed conditions, respectively. Results showed that the most active pathway for drought stress in maize were related to metabolic regulation at RNA level. And some genes, encoding enzymes involved in carbohydrate and lipid metabolism, were significantly down-regulated in drought-stressed plants. While, the transcription factors and genes, encoding catabolic or degradative enzymes, were over-expressed in maize early developing tassels under drought-stressed conditions, and among them, the transcripts of genes encoding exon-junction complexes involved in ＇RNA transcript＇ and ＇mRNA surveillance＇ pathways were significantly affected by drought stress. In addition, many other genes related to drought stress showed transcriptional changes at the later period of stress.