Project description:Floral organs are extremely sensitive to stress during anthesis and lead to severe yield loss. Rice anthers and pollinated pistils of two cultivars with contrasting tolerance to heat and drought stress under variable conditions, including control, heat, combined heat and drought stress, were used to explore gene expression pattern in male and female reproductive organs during anthesis under control and stress conditions. More gene regulation was induced by combined drought and heat stress than heat in anthers of both cultivars. N22 showed less regulation under combined stress than Moroberekan. The overlap of regulated genes between two cultivars was rather low, indicated the distinct molecular stress responses. We used whole genome microarrays to explore gene expression pattern and molecular mechanisms in male and female reproductive organs during anthesis under control and stress conditions in two rice cultivars, sought to identify the key transcripts that play roles in inducing heat and drought tolerance during reproduction in rice.
Project description:Rice is susceptible to both heat and drought stress, in particular during flowering and grain filling, when both grain yield and quality may be severely compromised. However, under field conditions, these two stresses rarely occur separately. Under well-watered conditions, plants avoid heat stress by transpirational cooling, while this is not possible under drought conditions. Although investigating combined heat and drought stress is clearly more agronomically relevant than analyzing the effects of the single stresses, only a few studies of this stress combination, in particular under field conditions, have been published. Furthermore, little is known about how plants respond during recovery from drought stress, which also determines plant survival. To address these knowledge gaps, three rice cultivars differing in heat and drought tolerance were grown in the field under control and drought conditions in three consecutive years. Drought was applied either during flowering or during early grain filling, resulting in simultaneous heat stress, leading to reduced grain yield and quality. Analysis by gas chromatography-mass spectrometry (GC-MS) showed distinct metabolic profiles for the three investigated organs (flag leaves, flowering spikelets, developing seeds). The metabolic responses of the plants also strongly differed between cultivars and organs, and between stress and rewatering conditions. Correlation analysis identified potential metabolic markers for grain yield and quality under combined heat and drought stress from stress- and rewatering-regulated metabolites and from metabolites with constitutive differences between the cultivars. These results show that GC-MS can resolve metabolic responses to combined heat and drought stress and subsequent rewatering in different organs of field-grown rice. The metabolite profiles can be used to identify potential marker metabolites for yield stability and grain quality that are expected to improve breeding efforts towards climate change resilient rice.
Project description:A heat and drought tolerant rice cultivar (N22) was grown in the field under control and drought conditions during the dry season in 2013. Drought was applied during early grain filling and resulted in simultaneous heat stress, leading to reduced grain yield and quality. Total RNA was extracted from developing seeds under stress and control (fully flooded) conditions and RNA-seq analysis was performed. These samples are a part of a bigger experiment analysing the responses of three contrasting rice cultivars (N22, Dular, Anjali) to combined heat and drought stress including different organs (developing seeds, flag leaves, flowering spikelets) and developmental stages (early grain filling, flowering) at the transcriptomic level.
Project description:In order to understand the mechanisms of Drought induced susceptibility (DIS) we’ve conducted a dual RNAseq experiment on rice infected tissues by Magnaporthe oryzae. At 4 days post inoculation tissues have been collected on mock inoculated and M. oryzae inoculated plants. Rice were conducted under two type of water regime: DIS Drought during three days before inoculation, NoDIS no drought before inoculation. RNAseq was conducted both on rice and fungal RNA.
Project description:Drought and heat are major abiotic stresses frequently coinciding to threaten rice production. Although hundreds of stress-related genes have been identified in the past two decades, very few genes have been confirmed to confer resistance to multiple stresses in crops. Here we report ONAC023, identified through NAC-centered gene regulatory network and genetic association analyses, is a hub stress-regulator that integrates the regulations of both drought and heat tolerance in rice. The loss-of-function mutant of ONAC023 showed significantly increased sensitivity to drought and heat stresses, whereas the overexpression of ONAC023 confers drought and heat tolerance at both seedling and reproductive stages. Notably, drought and heat stresses activated the function of ONAC023 not only by the induction of ONAC023 transcript but also by the nuclear accumulation of ONAC023 protein through a remorin-importin-α-assisted translocation. Under drought or heat stress, ONAC023 can directly target and promote the expression of functionally diverse downstream genes, such as OsPIP2;7, PGL3, OsFKBP20-1b, and OsSF3B1, which are involved in various stress-responsive processes including water transport, reactive oxygen species homeostasis, and alternative splicing (AS). Furthermore, genome-wide AS profiling revealed that the loss of ONAC023 function led to alternation of the encoding outcomes of thousands of AS transcripts under drought and heat stresses. These results manifested that ONAC023 is fine tuned to positively regulate drought and heat tolerance through the integration of multiple stress-responsive processes. Our findings provide not only an underlying connection between drought and heat responses, but also a promising candidate for engineering multi-stress-resilient rice.
Project description:Heat shock factors (Hsfs) are known to regulate heat and drought stress response by controlling the expression of heat shock proteins and oxidative stress responsive genes. Loss-of-function of OsHSFA2e gene resulted in increased sensitivity of rice plants to drought and heat stress. To identify the targets of OsHSFA2e and dissect the stress response pathway regulated by it, we performed transcriptome profiling of Oshsfa2e mutant plants under drought stress as well as well-watered conditions by RNA-sequencing.
Project description:To investigate the relative effects of drought and heat on the rice (Oryza sativa) transcriptome, we subjected rice seedlings to 3 levels of long-term drought or 2 levels of short-term heat stock
Project description:Plants show a high degree of developmental plasticity in response to external cues, including day length and environmental stress. Water scarcity in particular can interfere with photoperiodic flowering, resulting in the acceleration of the switch to reproductive growth in several species, a process called drought escape. However, other strategies are possible and drought stress can also delay flowering, albeit the underlying mechanisms have never been addressed at the molecular level. We investigated these interactions in rice, a short day species in which drought stress delays flowering. A protocol that allows the synchronization of drought with the floral transition was set up to profile the transcriptome of leaves subjected to stress under distinct photoperiods. We identified clusters of genes that responded to drought differently depending on day length. Exposure to drought stress under floral-inductive photoperiods strongly reduced transcription of EARLY HEADING DATE 1 (Ehd1), HEADING DATE 3a (Hd3a) and RICE FLOWERING LOCUS T 1 (RFT1), primary integrators of day length signals, providing a molecular connection between stress and the photoperiodic pathway. However, phenotypic and transcriptional analyses suggested that OsGIGANTEA (OsGI) does not integrate drought and photoperiodic signals as in Arabidopsis, highlighting molecular differences between between long and short day model species.
Project description:Drought and heat are major abiotic stresses frequently coinciding to threaten rice production. Despite hundreds of stress-related genes being identified, only a few have been confirmed to confer resistance to multiple stresses in crops. Here we report ONAC023, a hub stress regulator that integrates the regulations of both drought and heat tolerance in rice. ONAC023 positively regulates drought and heat tolerance at both seedling and reproductive stages. Notably, the functioning of ONAC023 is obliterated without stress treatment and can be triggered by drought and heat stresses at two layers. Besides the stress-induced expression, ONAC023 also exhibits cytoplasm-nucleus transport via a remorin-importin-α-assisted pathway regulated by the stress-dependent dephosphorylation of OsREM1.5. Under drought or heat stress, the nuclear ONAC023 can target and promote the expression of diverse genes, such as OsPIP2;7, PGL3, OsFKBP20-1b, and OsSF3B1, which are involved in various processes including water transport, reactive oxygen species homeostasis, and alternative splicing. These results manifest that ONAC023 is fine-tuned to positively regulate drought and heat tolerance through the integration of multiple stress-responsive processes. Our findings provide not only an underlying connection between drought and heat responses, but also a promising candidate for engineering multi-stress-resilient rice.
Project description:Phoenix dactylifera seedlings were exposed to heat, drought and combined heat & drought conditions in growth chambers. Leaf samples were collected for total RNA isolation (RNAseq, Illumina HiSeq 1000), and water soluble metabolites. The RNAseq of four biological replicates (two individuals per replicate) were compared against the control condition. Transcriptomics data suggests the combine heat and drought resembled heat response, whereas drought resembled more to control. The hallmarks of heat stress were visible in the transcriptomics data, such as protein misfolding, response to hydrogen peroxide and cell wall modification, as well as ABA signaling in the case of drought. Since the plants were exposed to the stress for several days before harvesting, the early signs of heat stress such as calcium and NO signaling were not detected anymore. In addition, data suggest a significant enrichment of circadian rhythm motifs in the differentially expressed genes in heat and combined heat and drought stresses, suggesting new stress avoidance strategies.