Project description:Phosphate starvation/sufficient rice seedling, root or shoot Pi-starvation or Pi-sufficient stresses responsible rice genes, including previously unannotated genes were identified by Illumina mRNA-seq technology. 53 million reads from Pi-starvation or Pi-sufficient root or shoot tissues were uniquely mapped to the rice genome, and these included 40574 RAP3 transcripts in root and 39748 RAP3 transcripts in shoot. We compared our mRNA-seq expression data with that from Rice 44K oligomicroarray, and about 95.5% (root) and 95.4% (shoot) transcripts supported by the array were confirmed expression both by the array and by mRNA-seq, Moreover, 11888 (root) and 11098 (shoot) RAP genes which were not supported by array, were evidenced expression with mRNA-seq. Furthermore, we discovered 8590 (root) and 8193 (shoot) previously unannotated transcripts upon Pi-starvation and/or Pi-sufficient.
Project description:A comprehensive time-course experiment of Pi-starved plants was undertaken, spanning medium (3 and 7 days), and long-term (21 days up to 52 days) Pi deprivation (âPi), as well as both short term (1 and 3 days) and long-term (31 days) recovery. The 52 days time point consisting of 21 days starvation +31 days recovery enabled investigation of the effects of long term resupply on Pi starved plants, and coincided with the emergence of the first panicles and grains. Pre-germinated rice seedlings were grown for 14 days in Pi sufficient conditions (0.32 mM Pi) before being transferred to either Pi sufficient (0.32 mM Pi) or Pi deficient (0 mM Pi) media for 21 days. After 21 days of Pi deficient treatment, half of the plants were either maintained under Pi deficient conditions or re-supplied with Pi (0.32 mM) for 1, 3 or 31 days. To confirm the effectiveness of the Pi starvation and resupply treatments, physiological and molecular analyses were performed.
Project description:To better understand the complex mechanisms regulating Pi homeostasis in rice (Oryza sativa L. cv. Nipponbare), a time course experiment was performed, where pre-germinated seedlings were grown hydroponically for two weeks on Pi-sufficient medium (0.32 mM Pi), before transferring half of the plants to Pi-deficient solution (0 mM Pi) for 21 days (d). After three weeks of Pi-starvation treatment, half of these plants where then re-supplied with Pi sufficient media for up to 24 hours (h). In total, nine time points were selected in order to cover short and long term responses to Pi starvation as well as the effects of Pi re-supply on Pi starved plants.
Project description:Fourteen days plants growth under hydroponic +P condition (200 µM) were treated with +P(200µM) or –P (no phosphate) for another 7 days, shoot of plants from 3 biological repeats were sampled for Affymetrix microarray analysis. We used microarrays to detail the global programme of gene expression underlying +Pi and -Pi condition between WT and spx1spx2 double mutant.
Project description:In order to shed light on the DNA methylation pathway mediating Pi starvation-induced changes in DNA methylation, the phosphate starvation experiment was repeated using an RNAi line that knocks DCL3a, a key factor involved in the canonical RdDM pathway.
Project description:A biological phenomenon in which hybrids exhibit superior phenotypes from its parental inbred lines known as heterosis, has been widely exploited in plant breeding and extensively used in crop improvement. Hybrid rice has immense potential to increase yield over other rice varieties and hence is crucial in meeting increasing demand of rice globally. Moreover, the molecular basis of heterosis is still not fully understood and hence it becomes imperative to unravel its genetic and molecular basis. In this context, RNA sequencing technology (RNA-Seq) was employed to sequence transcriptomes of two rice hybrids, Ajay and Rajalaxmi, their parental lines, CRMS31A (sterile line, based on WA-CMS) and CRMS32A (sterile line based on Kalinga-CMS) respectively along with the common restorer line of both hybrids, IR-42266-29-3R at two critical rice developmental stages viz., panicle initiation (PI) and grain filling (GF). Identification of differentially expressed genes (DEGs) at PI and GF stages will further pave the way for understanding heterosis. In addition, such kind of study would help in better understanding of heterosis mechanism and genes up-regulated and down-regulated during the critical stages of rice development for higher yield.
Project description:Phosphorus (Pi) starvation prevents a good match between light energy absorption and photosynthetic carbon metabolism. Photosynthetic electron-transport chain switches to use molecular oxygen as an electron carrier, generating photo-reactive oxygen species (photo-ROS) in chloroplast. In rice (Oryza sativa), DEEP GREEN PANICLE1 (DGP1) is robustly up-regulated in response to Pi-deficiency stress. DGP1 decreases the DNA-binding activities of the photosynthetic activators GLK1/2 on the genes involved in chlorophyll biosynthesis, light harvesting and electron transport. This Pi-starvation-induced mechanism dampens electron transport rates (ETRI and ETRII) and alleviates the electron-excessive stress in mesophyll cells. Meanwhile, DGP1 hijacks glycolytic enzymes GAPC1/2/3, redirecting glucose metabolism toward pentose phosphate pathway with superfluous NADPH production. Phenotypically, light irradiation induces O2– accumulation in Pi-starved WT leaves, but was observably accelerated in dgp1 mutant and impaired in GAPCsRNAi line and glk1glk2 double mutant. Interestingly, overexpression of DGP1 in rice caused hyposensitivity to the ROS-inducers (catechin and methyl viologen) and dgp1 mutant shows a similar inhibitory growth with the WT plants. We conclude that DGP1 gene serves as a specific antagonizer against Pi-starvation-induced photo-ROS, which integrates light-absorbing and anti-oxidative systems by orchestrating transcriptional and metabolic regulations, respectively.