Project description:Oilseed mustard, Brassica juncea, exhibits high levels of genetic variability for salinity tolerance. To obtain the global view of transcriptome and investigate the molecular basis of salinity tolerance in a salt-tolerant variety CS52 of B. juncea, we performed transcriptome sequencing of control and salt-stressed seedlings. De novo assembly of 184 million high-quality paired-end reads yielded 42,327 unique transcripts longer than 300 bp with RPKM ≥1. When compared with non-redundant proteins, we could annotate 67% unigenes obtained in our study. Based on the mapping to expressed sequence tags (ESTs), 52.6% unigenes are novel compared to EST data available for B. juncea and constituent genomes. Differential expression analysis revealed altered expression of 1469 unigenes in response to salinity stress. Of these, 587, mainly associated with ROS detoxification, sulfur assimilation and calcium signaling pathways, are up regulated. Notable of these is RSA1 (SHORT ROOT IN SALT MEDIUM 1) INTERACTING TRANSCRIPTION FACTOR 1 (RITF1) homolog up regulated by >100 folds in response to stress. RITF1, encoding a bHLH transcription factor, is a positive regulator of SOS1 and several key genes involved in scavenging of salt stress-induced reactive oxygen species (ROS). Further, we performed comparative expression profiling of key genes implicated in ion homeostasis and sequestration (SOS1, SOS2, SOS3, ENH1, NHX1), calcium sensing pathway (RITF1) and ROS detoxification in contrasting cultivars, B. juncea and B. nigra, for salinity tolerance. The results revealed higher transcript accumulation of most of these genes in B. juncea var. CS52 compared to salt-sensitive cultivar even under normal growth conditions. Together, these findings reveal key pathways and signaling components that contribute to salinity tolerance in B. juncea var. CS52. We report transcriptome sequencing of two-weeks-old seedlings of B. juncea var. CS52 under normal growth conditions (CTRL) and in response to salinity stress (SS) using Illumina paired-end sequencing
Project description:Oilseed mustard, Brassica juncea, exhibits high levels of genetic variability for salinity tolerance. To obtain the global view of transcriptome and investigate the molecular basis of salinity tolerance in a salt-tolerant variety CS52 of B. juncea, we performed transcriptome sequencing of control and salt-stressed seedlings. De novo assembly of 184 million high-quality paired-end reads yielded 42,327 unique transcripts longer than 300 bp with RPKM ≥1. When compared with non-redundant proteins, we could annotate 67% unigenes obtained in our study. Based on the mapping to expressed sequence tags (ESTs), 52.6% unigenes are novel compared to EST data available for B. juncea and constituent genomes. Differential expression analysis revealed altered expression of 1469 unigenes in response to salinity stress. Of these, 587, mainly associated with ROS detoxification, sulfur assimilation and calcium signaling pathways, are up regulated. Notable of these is RSA1 (SHORT ROOT IN SALT MEDIUM 1) INTERACTING TRANSCRIPTION FACTOR 1 (RITF1) homolog up regulated by >100 folds in response to stress. RITF1, encoding a bHLH transcription factor, is a positive regulator of SOS1 and several key genes involved in scavenging of salt stress-induced reactive oxygen species (ROS). Further, we performed comparative expression profiling of key genes implicated in ion homeostasis and sequestration (SOS1, SOS2, SOS3, ENH1, NHX1), calcium sensing pathway (RITF1) and ROS detoxification in contrasting cultivars, B. juncea and B. nigra, for salinity tolerance. The results revealed higher transcript accumulation of most of these genes in B. juncea var. CS52 compared to salt-sensitive cultivar even under normal growth conditions. Together, these findings reveal key pathways and signaling components that contribute to salinity tolerance in B. juncea var. CS52.
Project description:Although previous studies have addressed the possible benefits of arbuscular mycorrhizal (AM) symbiosis for rice plants under salinity, the underlying molecular mechanisms are still unclear. Here, we showed that rice colonized with AM fungi had better growth performance and higher K+/Na+ ratio under salt stress. Differentially expressed genes (DEGs) responding to AM symbiosis especially under salt stress were obtained from RNA sequencing. AM-regulated DEGs in cell wall modification and peroxidases categories were mainly upregulated in shoots, suggesting AM symbiosis might assist in relaxing the cell wall and scavenging reactive oxygen species (ROS). AM symbiosis indeed improved ROS scavenging capacity in rice shoots under salt stress. In addition, genes involved in Calvin cycle and terpenoid synthesis were enhanced by AM symbiosis in shoots and roots under salt stress, respectively. AM-upregulated cation transporters and aquaporin in both shoots and roots were highlighted. Strikingly, “protein tyrosine kinase activity” subcategory was the most significantly over-represented GO term among all AM-upregulated and downregulated DEGs in both shoots and roots, highlighting the importance of kinase on AM-enhanced salinity tolerance. Overall, our results from the transcriptomic analyses indicate that AM symbiosis uses a multipronged approach to help plants achieve salt stress tolerance.
Project description:Glycinebetaine-induced water-stress tolerance in codA-expressing transgenic indica rice is associated with up-regulation of several stress responsive genes. Rice (Oryza sativa L.), a non-accumulator of glycinebetaine (GB), is highly susceptible to abiotic stress. Transgenic rice with chloroplast-targeted choline oxidase encoded by the codA gene from Arthrobacter globiformis has been evaluated for inheritance of transgene up to R5 generation and water-stress tolerance. During seedling, vegetative and reproductive stages, transgenic plants could maintain higher activity of photosystem II and they show better physiological performance, e.g. enhanced detoxification of reactive oxygen species compared to wild-type plants under water-stress. Survival rate and agronomic performance of transgenic plants is also better than wild-type following prolonged water-stress. Choline oxidase converts choline into glycinebetaine and H2O2 in a single step. It is possible that H2O2 /GB might activate stress response pathways and prepare transgenic plants to mitigate stress. To check this possibility, microarray-based transcriptome analysis of transgenic rice has been done. It unraveled altered expression of many genes involved in stress responses, signal transduction, gene regulation, hormone signaling and cellular metabolism. Overall, 165 genes show more than 2 folds up-regulation at P value <0.01 in transgenic rice. Out of these, at least 50 genes are known to be involved in plant stress response. Exogenous application of H2O2 or GB to wild-type plants also induces such genes. Our data show that metabolic engineering for GB is a promising strategy for introducing stress tolerance in crop plants and which could be imparted, in part, by H2O2- and/or GB-induced stress response genes. Experiment Overall Design: Rice (Oryza sativa L.), transgenic plants expressing codA gene from Arthrobacter globiformis were compared with untransformed plants at seedling level
Project description:Adverse environmental conditions, such as salinity, heat waves, or water scarcity have a devastating impact on plant productivity. In nature, multiple abiotic stresses occur simultaneously and plants evolved unique responses to cope against combination stress that are not induced under a single stress condition. Here we coupled genome-wide transcriptional profiling and untargeted metabolomics with physiological and biochemical analyses to characterize the effect of salinity and heat applied jointly in the metabolism of tomato plants. Our results demonstrate that combination of salinity and heat causes unique reprogramming of tomato metabolic pathways, including changes in the expression of 1,388 genes and accumulation of 568 molecular features. Pathway enrichment analysis of transcript and metabolite data indicated that the proline and ascorbate pathways act synchronously to maintain cellular redox homeostasis, which was supported by measurements of enzymatic activity and oxidative stress markers. We also identified key transcription factors from the basic Leucine Zipper Domain (bZIP), Zinc Finger Cysteine-2/Histidine-2 (C2H2) and Trihelix families that are likely regulators of the identified up-regulated genes under salinity and heat combination. Our results expand the current understanding of how plants acclimate to environmental stresses in combination and unveiled the synergism between key cellular metabolic pathways for effective reactive oxygen species detoxification. Our study opens the door to elucidating the different signaling mechanisms for stress tolerance.
Project description:Glycinebetaine-induced water-stress tolerance in codA-expressing transgenic indica rice is associated with up-regulation of several stress responsive genes. Rice (Oryza sativa L.), a non-accumulator of glycinebetaine (GB), is highly susceptible to abiotic stress. Transgenic rice with chloroplast-targeted choline oxidase encoded by the codA gene from Arthrobacter globiformis has been evaluated for inheritance of transgene up to R5 generation and water-stress tolerance. During seedling, vegetative and reproductive stages, transgenic plants could maintain higher activity of photosystem II and they show better physiological performance, e.g. enhanced detoxification of reactive oxygen species compared to wild-type plants under water-stress. Survival rate and agronomic performance of transgenic plants is also better than wild-type following prolonged water-stress. Choline oxidase converts choline into glycinebetaine and H2O2 in a single step. It is possible that H2O2 /GB might activate stress response pathways and prepare transgenic plants to mitigate stress. To check this possibility, microarray-based transcriptome analysis of transgenic rice has been done. It unraveled altered expression of many genes involved in stress responses, signal transduction, gene regulation, hormone signaling and cellular metabolism. Overall, 165 genes show more than 2 folds up-regulation at P value <0.01 in transgenic rice. Out of these, at least 50 genes are known to be involved in plant stress response. Exogenous application of H2O2 or GB to wild-type plants also induces such genes. Our data show that metabolic engineering for GB is a promising strategy for introducing stress tolerance in crop plants and which could be imparted, in part, by H2O2- and/or GB-induced stress response genes.
Project description:Global warming has great impacts on plant growth and development. Heat shock transcription factors are the master regulators of heat stress response to alleviate protein misfolding in the cytosol in plants. However, how plants deal with accumulation of misfolded proteins in the endoplasmic reticulum (ER) under heat stress conditions is less understood, especially in crops such as in rice. Here we report a positive feed-back loop mediated by the membrane-associated transcription factors NTL3 and bZIP74 in heat stress response in rice. In response to heat stress, the ER-membrane-associated bZIP74 is activated and up-regulate the expression of NTL3 in rice; NTL3 encodes an ER-membrane-associated transcription factor that is activated and regulate downstream genes including bZIP74 involved in protein folding and reactive oxygen species scavenging. Loss-of-function mutations of NTL3 are sensitive to heat stress while inducible expression of the processed form of NTL3 increases heat stress tolerance in rice seedlings. Our work reveals the important role of NTL3 in ER stress response for heat stress tolerance in rice.
Project description:Alkali-salinity is a major abiotic stress that limits plant growth and productivity. Studying mechanisms of alkali-salinity tolerance in halophytic plants will provide valuable information for underlying plant alkali-salinity tolerance. Puccinellia tenuiflora is considered as an ideal model plant for studying the alkali-salinity tolerant mechanisms in plants. In this study, the NaHCO3-responsive molecular mechanisms in P. tenuiflora leaves were investigated using a combined physiological and proteomic approaches. Our results implied some specific NaHCO3-responsive mechanisms in leaves from P. tenuiflora. They are (1) reduction of photosynthesis attributed to the decrease of the abundance of Calvin cycle enzymes, (2) accumulation of Na+ and K+ caused ion-specific stress, (3) accumulation of proline, soluble sugar and betaine enhanced the ability of osmotic regulation, (4) diverse reactive oxygen species (ROS) scavenging mechanisms under different NaHCO3 concentrations, and (5) alternative protein synthesis and processing strategies in chloroplast and cytoplasm. All these provide important evidence for understanding NaHCO3-responsive mechanisms in P. tenuiflora.
Project description:Soil salinity is a major environmental stress that restricts crop growth and yield. Here, crucial proteins and biological pathways were investigated under salt-stress and recovery conditions in Tritipyrum “Y1805” to explore its salt-tolerance mechanism. In total, 44 and 102 differentially expressed proteins (DEPs) were identified in “Y1805” under salt-stress and recovery conditions, respectively. A proteome-transcriptome-associated analysis revealed that the expression patterns of 13 and 25 DEPs were the same under salt-stress and recovery conditions, respectively. “Response to stimulus”, “antioxidant activity”, “carbohydrate metabolism”, “amino acid metabolism”, “signal transduction”, “transport and catabolism” and “biosynthesis of other secondary metabolites” were present under both conditions in “Y1805”. In addition, “energy metabolism” and “lipid metabolism” were recovery-specific pathways, while “antioxidant activity”, and “molecular function regulator” under salt-stress conditions, and “virion” and “virion part” during recovery, were “Y1805”-specific compared with the salt-sensitive wheat “Chinese Spring”. “Y1805” contained 83 specific DEPs related to salt-stress responses. The strong salt tolerance of “Y1805” could be attributed to the strengthened cell walls, reactive oxygen species scavenging, osmoregulation, phytohormone regulation, transient growth arrest, enhanced respiration, ammonium detoxification, transcriptional regulation and error information processing. These data will facilitate an understanding of the molecular mechanisms of salt tolerance and aid in the breeding of salt-tolerant wheat.
Project description:Ascorbic acid (AA) is known to play a vital role in plant growth and detoxification of reactive oxygen species, however little is known about the significance of AA oxidation in plant defence against pathogens. • The role of ascorbate oxidation in rice defence against root-knot nematodes, Meloidogyne graminicola, was tested with application of AA, ascorbate oxidase (AO), dehydroascorbic acid (DHA), biosynthesis inhibitors and use of mutants. Transcriptome analysis was done on AO treated plants, and hormone measurements were executed to confirm the results. Biochemical analyses were used to study oxidative stress markers, including accumulation of H2O2, , malondialdehyde and AA/DHA.