Project description:Water deficit stress between the booting and grain filling stages significantly affect grain yield and quality of hard red winter wheat. Several stress tolerant cultivars with different adaptation mechanisms have been released and are widely cultivated on the Southern Great Plains of the US. However, the physiological, molecular, and genetic basis of adaptation to drought stress for these cultivars remains unknown. Use of transcriptome profiling to identify drought responsive genes in hexaploid wheat is a challenging process given the quantitative nature of drought stress, genome complexity, and the intricacy of interaction effects. If the information generated from functional genomics studies is to be used in molecular breeding programs for cultivar development, it is highly desirable to use cultivars better adapted for the region. In the current study we used two well-adapted, drought-tolerant, high-yielding, cultivated varieties, TAM 111 and TAM 112, which appear to have different adaptation mechanisms, to identify drought stress induced transcripts during heading and early dough stages. A set of 24 Affymetrix GeneChip wheat genome arrays (2 cultivars; 2 water treatments; 2 sampling stages; 3 biological replicates) from plants subjected to water deficit stress under controlled glasshouse conditions. Differentially expressed genes were identified using a ANOVA (p<0.01) controlling false discovery rate (FDR, q<0.01) using Benjamini Hochberg approach.
Project description:To better understand the regulatory mechanisms of water stress response in wheat, the transcript profiles in roots of two wheat genotypes, namely, drought tolerant 'Luohan No.2' (LH) and drought susceptible 'Chinese Spring' (CS) under water-stress were comparatively analyzed by using the Affymetrix wheat GeneChip®. A total of 3831 transcripts displayed 2-fold or more expression changes, 1593 transcripts were induced compared with 2238 transcripts were repressed, in LH under water-stress; Relatively fewer transcripts were drought responsive in CS, 1404 transcripts were induced and 1493 were repressed. Comparatively, 569 transcripts were commonly induced and 424 transcripts commonly repressed in LH and CS under water-stress. 689 transcripts (757 probe sets) identified from LH and 537 transcripts (575 probe sets) from CS were annotated and classified into 10 functional categories, and 74 transcripts derived from 80 probe sets displayed the change ratios no less than 16 in LH or CS. Several kinds of candidate genes were differentially expressed between the LH and CS, which could be responsible for the difference in drought tolerance of the two genotypes. Two common wheat (Triticum aestivum L.) cultivars, Luohan No.2 (LH) and Chinese Spring (CS), were used for this study. Seedlings at the two leaf stage were stressed by cultured in PEG solutions for 6h, and some other seedlings were cultured in tap water as control. Root samples of LH and CS at 6h after the stress treatment and untreated control were prepared for microarray analysis.
Project description:To better understand the regulatory mechanisms of water stress response in wheat, the transcript profiles in roots of two wheat genotypes, namely, drought tolerant 'Luohan No.2' (LH) and drought susceptible 'Chinese Spring' (CS) under water-stress were comparatively analyzed by using the Affymetrix wheat GeneChip®. A total of 3831 transcripts displayed 2-fold or more expression changes, 1593 transcripts were induced compared with 2238 transcripts were repressed, in LH under water-stress; Relatively fewer transcripts were drought responsive in CS, 1404 transcripts were induced and 1493 were repressed. Comparatively, 569 transcripts were commonly induced and 424 transcripts commonly repressed in LH and CS under water-stress. 689 transcripts (757 probe sets) identified from LH and 537 transcripts (575 probe sets) from CS were annotated and classified into 10 functional categories, and 74 transcripts derived from 80 probe sets displayed the change ratios no less than 16 in LH or CS. Several kinds of candidate genes were differentially expressed between the LH and CS, which could be responsible for the difference in drought tolerance of the two genotypes.
Project description:Purpose: To identify abiotic stress responsive and tissue specific miRNAs at genome wide level in wheat (Triticum aestivum) Results: Small RNA libraries were constructed from four tissues (root, shoot, mature leaf and spikelets) and three stress treatments of wheat seedlings (control, high temperature, salinity and water-deficit). A total of 59.5 million reads were obtained by high throughput sequencing of eight wheat libraries, of which 32.5 million reads were found to be unique. Using UEA sRNA workbench we identified 47 conserved miRNAs belonging to 20 families, 1030 candidate novel and 51 true novel miRNAs. Several of these miRNAs displayed tissue specific expression whereas few were found to be responsive to abiotic stress treatments. Target genes were predicted for miRNAs identified in this study and their grouping into functional categories revealed that the putative targets were involved in diverse biological processes. RLM-RACE of predicted targets of three conserved miRNAs (miR156, miR160 and miR164) confirmed their mRNA cleavage, thus indicating their regulation at post-transcriptional level by corresponding miRNAs. Expression profiling of confirmed target genes of these miRNAs was also performed. Conclusions: This is the first comprehensive study on profiling of miRNAs in a variety of tissues and in response to several abiotic stresses in wheat. Our findings provide valuable resource for better understanding on the role of miRNAs in stress tolerance as well as plant development. Additionally, this information could be utilized for designing wheat plants for enhanced abiotic stress tolerance and higher productivity.
Project description:Based on EST-based in silico gene expression analysis a 15k oligonucleotid microarray has been developped in order to monitor environmental stress-dependent gene expression changes in the wheat caryopsis. Using this array, the effect of water withdrawal, with and and without additional heat stress, during the first five days of grain development (0-5 DAA) has been investigated on two wheat cultivars differing in their drought sensitivity. The combined effect of heat and drought (DH) on gene expression was much significant (8-10% of the investigated genes changed >2-fold) in contrast to drought alone (1.5%). Drought and heat stress resulted in the co-ordinated change of the expression of storage proteins, some enzymes involved in sugar/starch metabolism, cell division-related and histone proteins, certain transcription factors, heat shock proteins, proteases and aquaporins. The potential link between the observed gene expression changes and the parallel histological observations indicating the accelerated development of the stressed grains is discussed.
Project description:Purpose: To identify abiotic stress responsive and tissue specific miRNAs at genome wide level in wheat (Triticum aestivum) Results: Small RNA libraries were constructed from four tissues (root, shoot, mature leaf and spikelets) and three stress treatments of wheat seedlings (control, high temperature, salinity and water-deficit). A total of 59.5 million reads were obtained by high throughput sequencing of eight wheat libraries, of which 32.5 million reads were found to be unique. Using UEA sRNA workbench we identified 47 conserved miRNAs belonging to 20 families, 1030 candidate novel and 51 true novel miRNAs. Several of these miRNAs displayed tissue specific expression whereas few were found to be responsive to abiotic stress treatments. Target genes were predicted for miRNAs identified in this study and their grouping into functional categories revealed that the putative targets were involved in diverse biological processes. RLM-RACE of predicted targets of three conserved miRNAs (miR156, miR160 and miR164) confirmed their mRNA cleavage, thus indicating their regulation at post-transcriptional level by corresponding miRNAs. Expression profiling of confirmed target genes of these miRNAs was also performed. Conclusions: This is the first comprehensive study on profiling of miRNAs in a variety of tissues and in response to several abiotic stresses in wheat. Our findings provide valuable resource for better understanding on the role of miRNAs in stress tolerance as well as plant development. Additionally, this information could be utilized for designing wheat plants for enhanced abiotic stress tolerance and higher productivity. Total eight (three stress, one control and four tissue specific small RNA libraries were pepared and sequenced independently [wheat control (WC), wheat high temperature stressed (WHTS), wheat salinity stressed (WSS) and wheat drought stressed (WDS), wheat shoot(WSH), wheat leaf (WLF), wheat flower(WFL), wheat root(WRT)] on Illumina GAIIx
Project description:This study evaluated the level of genetic variation among 543 wheat associations differing in K-deficiency tolerance at seedling and adult plant stages. Two of the 543 wheat associations, i.e. KN9204 and BN207, were identified as extreme K-deficiency tolerant and sensitive cultivars, respectively. We further conducted transcriptomic and metabolomics analyses using the roots of KN9204 and BN207 under normal or K-deficient conditions.Integrated analysis of gene expression and metabolite profiles revealed that dramatically more genes including those involved in ion homeostasis, cellular reactive oxygen species (ROS) homeostasis and glutamine synthetase pathways were induced in KN9204 as compared with BN207 under K-deficient conditions, which might indicate their unique roles in regulating plant K-starvation tolerance. These findings provided a better understanding of molecular responses of root adaptive strategies to K deprivation in wheat.
Project description:Based on EST-based in silico gene expression analysis a 15k oligonucleotid microarray has been developped in order to monitor environmental stress-dependent gene expression changes in the wheat caryopsis. Using this array, the effect of water withdrawal, with and and without additional heat stress, during the first five days of grain development (0-5 DAA) has been investigated on two wheat cultivars differing in their drought sensitivity. The combined effect of heat and drought (DH) on gene expression was much significant (8-10% of the investigated genes changed >2-fold) in contrast to drought alone (1.5%). Drought and heat stress resulted in the co-ordinated change of the expression of storage proteins, some enzymes involved in sugar/starch metabolism, cell division-related and histone proteins, certain transcription factors, heat shock proteins, proteases and aquaporins. The potential link between the observed gene expression changes and the parallel histological observations indicating the accelerated development of the stressed grains is discussed. 8 samples with 2 biological replicate using dye swap
Project description:Wheat cultivars ‘TAM 111’ and ‘TAM 112’ have been dominantly grown in the Southern U.S. Great Plains for many years due to their excellent, yet variable, drought tolerance. To identify the molecular basis and genetic control of drought tolerance in these two landmark cultivars, RNA-seq analysis was conducted to compare gene expression difference in flag leaves under fully irrigated (wet) and water deficient (dry) conditions. Of the 122,017 gene sequences assembled, 2,254 genes showed significantly altered expression patterns under dry and wet conditions in the two cultivars. TAM 111 had 593 and 1,532 dry-wet differentially expressed genes (DEGs), and TAM 112 had 777 and 1,670 at heading and grain-filling stages, respectively. The two cultivars have 1,214 (53.9%) dry-wet DEGs in common, which agreed with their excellent adaption to drought, but 438 and 602 dry-wet DEGs were respectively shown only in TAM 111 and TAM 112 suggested that each may have a specific mechanism to cope with drought. Annotation of all 2,254 genes with dry-wet expression difference found 1,855 have functions related to biosynthesis, stress responses, defense responses, transcription factors and cellular components related to ion or protein transportation and signal transduction. Comparing hierarchical structure of biological processes, molecule functions and cellular components revealed the significant regulation differences between TAM 111 and TAM 112, particularly for genes of phosphorylation and adenyl ribonucleotide binding, and proteins located in nucleus and plasma membrane. Comparing gene expressions involved in responses to stresses of water deprivation, heat and oxidative, ABA-induced signal pathway and transcription regulation found TAM 112 have more specific dry-wet DEGs than TAM 111 with most of them up-regulated, indicating that TAM 112 is more active than TAM 111 in response to drought. In addition, 399 dry-wet DEGs with unknown functions included 258 genes encoding predicted uncharacterized proteins and 141 unannotated genes with no similar sequences identified in the databases. These may represent novel genes related to drought response in TAM 111 or TAM 112. This research thus revealed different drought-tolerance mechanisms in TAM 111 and TAM 112 and identified useful drought tolerance genes for wheat adaption.
Project description:Background: MicroRNAs are endogenous small noncoding RNAs that play critical roles in plant abiotic stress responses. The interaction between miRNA-mRNA targets and their regulatory pathways in response to water deficit stress has been investigated in many plant species. However, the miRNA transcriptome of durum wheat (Triticum turgidum L. ssp. durum) is poorly characterised, with little known about miRNA functions related to water deficit stress. Yield loss in durum wheat can be exacerbated due to minimal rainfall in the early reproductive stages of development during Spring in Australia. This study describes genotypic differences in the miRNAome between water deficit tolerant/sensitive durum, using flag leaf and developing head tissue, and more specifically identifies miRNAs associated with water deficit stress. Results: Small RNA libraries (96 in total) were constructed from flag leaf and developing head tissues of four durum genotypes (Tamaroi, Yawa, EGA Bellaroi, Tjilkuri), with or without water deficit stress. Illumina sequencing and subsequent analysis detected 110 conserved miRNAs and 159 novel candidate miRNA hairpins. Statistical analysis of the abundance of sequencing reads revealed 66 conserved miRNAs and five novel miRNA hairpins showing differential expression under water deficit stress. During stress, several conserved and novel miRNAs showed unambiguous inverted regulatory profiles between the durum genotypes studied. Several miRNAs were also identified to have different abundance in the flag leaf compared to the developing head regardless of treatment. Predicted mRNA targets from four novel durum miRNAs were characterised using Gene Ontology (GO) which revealed functions common to stress responses and plant development. Conclusion: For the first time, we present a comprehensive study of the miRNA transcriptome of flag leaf and developing head tissues in different durum genotypes under water deficit stress. The identification of differentially expressed miRNAs provides molecular evidence that miRNAs are potential determinants of water stress tolerance in durum wheat. GO analysis of predicted targets contributes to the understanding of genotype-specific physiological responses leading to stress tolerance capacity. Further functional analysis of specific stress responsive miRNAs identified, and their interaction with mRNA targets is ongoing and will assist in developing future durum wheat varieties with enhanced water deficit stress tolerance.