Project description:Gene expression profiles of ethanol treated drought-stressed roots and shoots was performed at 3, 24, and 72 h after ethanol treatment and 1, 3, and 5 days after drought stress were analyzed using the custom microarray Agilent-034592.
Project description:External application of acetic acid has been recently reported to enhance the survival to drought in plants such as Arabidopsis, rapeseed, maize, rice and wheat, but the effects of acetic acid application on increased drought tolerance in woody plants such as a tropical crop “cassava” remain elusive. A molecular understanding of acetic acid-induced drought avoidance in cassava will contribute to the development of technology that can be used to enhance drought tolerance without resorting to transgenic technology or advancements in cassava cultivation. In the present study, morphological, physiological and molecular responses to drought were analyzed in cassava after the treatment with acetic acid. Results indicated that the acetic acid-treated cassava plants had a higher level of drought avoidance than water-treated, control plants. Specifically, higher leaf relative water content, and chlorophyll and carotenoid levels were observed as soils dried out during the drought treatment. Leaf temperatures in acetic acid-treated cassava plants were higher relative to leaves on plants pretreated with water and the increase of ABA content was observed in leaves of acetic acid-treated plants, suggesting that stomatal conductance and the transpiration rate in leaves of acetic acid-treated plants decreased to maintain relative water contents and avoid drought. Transcriptome analysis revealed that the acetic acid treatment increased the expression of ABA signaling-related genes, such as OPEN STOMATA 1 (OST1) and protein phosphatase 2C; as well as drought response and tolerance-related genes, such as outer membrane tryptophan-rich sensory protein (TSPO), and heat shock proteins. Collectively, the external application of acetic acid enhances drought avoidance in cassava through the upregulation of ABA signaling pathway genes and several stress response- and tolerance-related genes. These data support the idea that adjustments of the acetic acid application to plants is useful to enhance drought tolerance in order to minimize the growth inhibition in the agricultural field.
Project description:With climate change, droughts are expected to be more frequent and severe, severely impacting plant biomass and quality. Here, we show that overexpressing the Arabidopsis gene AtFtsHi3 (FtsHi3OE) enhances drought-tolerant phenotypes without compromising plant growth. AtFtsHi3 encodes a chloroplast envelope pseudo-protease; knock-down mutants (ftshi3-1) are found to be drought tolerant but exhibit stunted growth. Altered AtFtsHi3 expression therefore leads to drought tolerance, while only diminished expression of this gene leads to growth retardation. To understand the underlying mechanisms of the enhanced drought tolerance, we compared the proteomes of ftshi3-1 and pFtsHi3-FtsHi3OE (pFtsHi3-OE) to wild-type plants under well-watered and drought conditions. Drought-related processes like osmotic stress, water transport, and abscisic acid response were enriched in pFtsHi3-OE and ftshi3-1 mutants following their enhanced drought response compared to wild-type. The knock-down mutant ftshi3-1 showed an increased abundance of HSP90, HSP93, and TIC110 proteins, hinting at a potential downstream role of AtFtsHi3 in chloroplast pre-protein import. Mathematical modeling was performed to understand how variation in the transcript abundance of AtFtsHi3 can, on the one hand, lead to drought tolerance in both overexpression and knock-down lines, yet, on the other hand, affect plant growth so differently. The results led us to hypothesize that AtFtsHi3 may form complexes with at least two other protease subunits, either as homo- or heteromeric structures. Enriched amounts of AtFtsH7/9, AtFtsH11, AtFtsH12, and AtFtsHi4 in ftshi3-1 suggest a possible compensation mechanism for these proteases in the hexamer.
Project description:Plants have evolved a sophisticated defense system to survive under natural drought conditions. MicroRNAs (miRNA) are small noncoding RNAs that act as a post-transcriptional regulator in the environmental stress response and developmental process. Although many studies have reported the involvement of the miRNAs in drought response, molecular mechanisms by which miRNAs confer drought tolerance remain elusive. Here, we show that MIR171f, a member of MIR171 gene family, is mainly expressed in response to drought stress and regulate transcript levels of SCARECROW-LIKE6-I (SCL6-I) and SCL6-II. The SCL6 genes are known to be involved in shoot branching and flag leaf morphology. The MIR171f-overexpressing (MIR171f-OE) transgenic plants showed reduced drought symptoms as compared with non-transgenic (NT) control plants under both field drought and PEG-mediated dehydration stress conditions. Transcriptome analysis using the MIR171f-OE and mir171f-K/O mutants revealed that MIR171f regulates the expression of flavonoid biosynthesis genes, consequently leading to drought tolerance. Flavonoid biosynthesis genes were up-regulated in MIR171f-OE plants as compared with NT control plants under both normal and drought conditions. Together, our findings demonstrated that MIR171f plays an important role in plant drought-tolerance mechanism by regulating transcript levels of SCL6-I and SCL6-II.
Project description:Plants have evolved to possess adaptation mechanism to cope with drought stress by reprograming transcriptional networks through drought responsive transcription factors, which in turn mediate morphological and physiological changes. NAM, ATAF1-2, and CUC2 (NAC) transcription factors are known to be associated with various developmental processes and stress tolerance. In this study, we functionally characterized the rice drought responsive NAC transcription factor OsNAC14. OsNAC14 was predominantly induced at meiosis stage, and induced by drought, high salinity, ABA and low temperature in leaves than roots. Overexpression of OsNAC14 resulted in drought tolerance at the vegetative growth stage and enhanced filling rate at vegetative growth. OsNAC14 overexpression elevated expression of genes related to DNA damage repair, defense response, strigolactone biosynthesis, which correlated with resistance to drought tolerance. Furthermore, OsNAC14 directly bound to the promoter of drought inducible OsRAD51A1, a key component in homologous recombination in DNA repair system. These results indicate that OsNAC14 mediate drought tolerance by recruiting factors involved in DNA damage repair and defense response to enable plant to protect from cellular damage caused by drought stress, thereby provide mechanism for drought tolerance.
Project description:In plants, drought stress is a major growth limiting factor causing cell water loss through open stomata. In this study, guard cell-specific transcripts from drought-stressed Arabidopsis plants were analyzed and a down-regulation of β-amylase 1 (BAM1) was found. In previous studies, BAM1 was shown to be involved in stomatal starch degradation under ambient conditions. Impaired starch breakdown of bam1 mutant plants was accompanied by decreased stomatal opening. Here, we show that drought tolerance of bam1 mutant plants is improved as compared to wild type controls. Microarray-analysis of stomata-specific transcripts from bam1 mutant plants revealed a significant down-regulation of genes encoding aquaporins, auxin- and ethylene-responsive factors and cell-wall modifying enzymes. This expression pattern suggests that reduced water-uptake and limited cell wall extension are associated with the closed state of stomata of bam1 mutant plants. Together these data suggest that regulation of stomata-specific starch turnover is important for adapting stomata opening to environmental needs and its breeding manipulation may result in drought tolerant crop plants.
Project description:In plants, drought stress is a major growth limiting factor causing cell water loss through open stomata. In this study, guard cell-specific transcripts from drought-stressed Arabidopsis plants were analyzed and a down-regulation of β-amylase 1 (BAM1) was found. In previous studies, BAM1 was shown to be involved in stomatal starch degradation under ambient conditions. Impaired starch breakdown of bam1 mutant plants was accompanied by decreased stomatal opening. Here, we show that drought tolerance of bam1 mutant plants is improved as compared to wild type controls. Microarray-analysis of stomata-specific transcripts from bam1 mutant plants revealed a significant down-regulation of genes encoding aquaporins, auxin- and ethylene-responsive factors and cell-wall modifying enzymes. This expression pattern suggests that reduced water-uptake and limited cell wall extension are associated with the closed state of stomata of bam1 mutant plants. Together these data suggest that regulation of stomata-specific starch turnover is important for adapting stomata opening to environmental needs and its breeding manipulation may result in drought tolerant crop plants.
Project description:To identify novel microRNAs that are associated with drought tolerance in two different cowpea genotypes, we generated small RNA sequences from adult cowpea plants under control and dought stress treatments. Over 79 million raw reads were generated and numerous novel microRNAs are identified, including some associated with drought tolerance.
Project description:The AP2/ERF family is one of the plant-specific transcription factors (TFs) whose members have been associated with various developmental processes and stress tolerance. Here, we functionally characterized the drought-inducible OsERF48, a group Ib member of the rice ERF family that contains four conserved motifs, CMI-1, 2, 3 and 4. Transactivation assay in yeast revealed that the CMI-1 at the C-terminal end was essential for its transcriptional activity. When the OsERF48 was overexpressed in an either root-specific (ROXOsERF48) or whole-body (OXOsERF48) expression manner, both transgenic plants showed a longer and denser root phenotype than the nontransgenic (NT) controls. When plants were grown on a 40% PEG-infused medium, an in vitro drought condition, ROXOsERF48 plants showed a more vigorous root growth over OXOsERF48 and NT plants. In addition, the ROXOsERF48 plants exhibited higher grain yield under field-drought conditions than OXOsERF48 and NT plants. We constructed a putative regulatory network of OsERF48 by cross-referencing of RNA-seq data of ROXOsERF48 roots with a co-expression network database, revealing an involvement of 20 drought-related genes. These include genes for stress signaling, carbohydrate metabolism, cell-wall proteins, and drought-response. More importantly, OsCML16, a key gene for calcium signaling during abiotic stress, was identified to be the direct target of OsERF48 by the ChIP-qPCR and the protoplast transient assay. Thus, our results demonstrated that OsERF48 regulates OsCML16, a calmodulin-like protein gene that enhance root growth and drought tolerance.