Project description:The OsbZIP23 transcription factor has been characterized for its essential role in drought resistance in rice, but the mechanism is unknown. Here, we performed genome-wide identification of OsbZIP23 targets by immunoprecipitation sequencing (ChIP-seq) and RNA Sequencing (RNA-Seq) analyses in the OsbZIP23-overexpression, osbzip23 mutant, and wild-type rice under normal and drought stress conditions. OsbZIP23 directly regulates a large number of reported genes that function in stress response, hormone signaling, and developmental processes. Among these targets, we found that OsbZIP23 could positively regulate OsPP2C49, and overexpression of OsPP2C49 in rice resulted in significantly decreased sensitivity of the ABA response and rapid dehydration. Moreover, OsNCED4 (9-cis-epoxycarotenoid dioxygenase 4), a key gene in ABA biosynthesis, was also positively regulated by OsbZIP23. Together, our results suggest that OsbZIP23 acts as a central regulator in ABA signaling and biosynthesis, and drought resistance in rice.
Project description:New shoot growth from underground adventitious buds of leafy spurge is critical for survival of this invasive perennial weed after episodes of severe abiotic stress. Because global climate change is expected to increase abiotic stress, such as dehydration, objectives of this study include examining the impact that dehydration stress has on molecular mechanisms associated with vegetative reproduction. Greenhouse plants were exposed to mild- (3-day), intermediate- (7-day), severe- (14-day) and extended- (21-day) dehydration treatments, prior to decapitation of aerial tissue and rehydration of soil to induce new vegetative shoot growth. Compared to well-watered control plants, mild-dehydration accelerated new vegetative shoot growth but intermediate- and severe-dehydration treatments both delayed and reduced shoot growth, and 21-day dehydration treatment inhibited initiation of new vegetative shoots and was considered a lethal treatment. Overall, transcriptome profiles revealed that 2109 genes were differentially-expressed (P<0.05) in crown buds in response to the various dehydration treatments. Sub-network enrichment analyses identified central hubs of over-represented genes involved in processes such as hormone responses and signaling (e.g., ABA, auxin, ethylene, GA, and JA), response to abiotic stress (DREB1A/2A) and light (PIF3), phosphorylation (CLV1, MPK3/4/6, SOS2), gene silencing (miRNA156/172a), circadian regulation (CRY2, LHY, PHYA/B), and flowering (AGL8/20, AP2, FLC). Further, results from this and previous studies highlight HY5, MAF3, MYB-like/RVE1 and RD22 as molecular markers for endodormancy in crown buds of leafy spurge. Early response to dehydration also highlighted involvement of upstream ethylene and jasmonate signaling, whereas longer-term dehydration impacted ABA signaling. The identification of conserved ABRE- and MYC-consensus, cis-acting elements in the promoter of a leafy spurge gene similar to Arabidopsis MYB-like/RVE1 (AT5G17300) implicates a potential role for ABA signaling in its dehydration-induced expression. Response of these molecular mechanisms to dehydration-stress provides insights on the ability of invasive perennial weeds to adapt and survive under harsh environments, which provide new insights for addressing future management practices.
Project description:New shoot growth from underground adventitious buds of leafy spurge is critical for survival of this invasive perennial weed after episodes of severe abiotic stress. Because global climate change is expected to increase abiotic stress, such as dehydration, objectives of this study include examining the impact that dehydration stress has on molecular mechanisms associated with vegetative reproduction. Greenhouse plants were exposed to mild- (3-day), intermediate- (7-day), severe- (14-day) and extended- (21-day) dehydration treatments, prior to decapitation of aerial tissue and rehydration of soil to induce new vegetative shoot growth. Compared to well-watered control plants, mild-dehydration accelerated new vegetative shoot growth but intermediate- and severe-dehydration treatments both delayed and reduced shoot growth, and 21-day dehydration treatment inhibited initiation of new vegetative shoots and was considered a lethal treatment. Overall, transcriptome profiles revealed that 2109 genes were differentially-expressed (P<0.05) in crown buds in response to the various dehydration treatments. Sub-network enrichment analyses identified central hubs of over-represented genes involved in processes such as hormone responses and signaling (e.g., ABA, auxin, ethylene, GA, and JA), response to abiotic stress (DREB1A/2A) and light (PIF3), phosphorylation (CLV1, MPK3/4/6, SOS2), gene silencing (miRNA156/172a), circadian regulation (CRY2, LHY, PHYA/B), and flowering (AGL8/20, AP2, FLC). Further, results from this and previous studies highlight HY5, MAF3, MYB-like/RVE1 and RD22 as molecular markers for endodormancy in crown buds of leafy spurge. Early response to dehydration also highlighted involvement of upstream ethylene and jasmonate signaling, whereas longer-term dehydration impacted ABA signaling. The identification of conserved ABRE- and MYC-consensus, cis-acting elements in the promoter of a leafy spurge gene similar to Arabidopsis MYB-like/RVE1 (AT5G17300) implicates a potential role for ABA signaling in its dehydration-induced expression. Response of these molecular mechanisms to dehydration-stress provides insights on the ability of invasive perennial weeds to adapt and survive under harsh environments, which provide new insights for addressing future management practices. Changes in transcript abundance for underground adventitious buds of leafy spurge which were exposed various levels of dehydration stress (Day-3, -7, -14, -16, -21) are analysed relative to controls (Day-0).