Project description:Overexpression of OsMYB103L leads to leaf rolling in transgenic rice plants. To explore the possible molecular mechanism of OsMYB103L’s effects on rice leaf development, we examined the expression profiles of OsMYB103L overexpression transgenic rice plants and wild type leaf blades using Digital Gene Expression (DGE) profiling analysis.
Project description:The aim of this study was to characterize the tissue tolerance mechanisms of rice under salt stress. Our preliminary experiment identified a japonica rice landrace Shuzenji-kokumai (SZK), which is considered to be tissue-tolerant because it can maintain better growth than salt-sensitive rice while having a high Na+ concentration in the shoots under salt stress. These mechanisms differ from those of most salt-tolerant rice varieties, which have low Na+ concentrations in the shoots. We compared the physiological and molecular characteristics of SZK with those of FL478, a salt-tolerant variety, and Kunishi, a salt-sensitive variety. Under salt stress conditions, SZK accumulated high levels of Na+ in roots, leaf sheaths, and leaf blades, which were almost as high as those in the salt-sensitive Kunishi. Simultaneously, SZK maintained better growth and physiological status, as determined by its higher dry weight, lower electrolyte leakage ratio, and lower malondialdehyde concentration. OsNHX1 and OsNHX2 were up-regulated in the leaf sheaths of SZK, suggesting that Na+ is compartmentalized in the vacuole to avoid Na+ toxicity. In contrast, FL478 showed up-regulation of OsHKT1;5 and OsSOS1 in the roots, which exclude Na+ from the shoots. RNA-seq analysis showed that 4623 and 1998 differentially expressed genes (DEGs) were detected in the leaf sheaths and leaf blades of SZK, respectively. Among them, the HSP (heat shock protein) gene expression was highly up-regulated only in SZK, indicating that SZK protects against the protein damage caused by Na+ toxicity. Our findings suggest that SZK has atypical survival mechanisms under salt-stress conditions. These mechanisms offer potential traits for improving salt tolerance in rice.
Project description:Plants grown under a canopy recognize changes in light quality and modify their growth patterns; this modification is known as shade avoidance syndrome. In leaves, leaf blade expansion is suppressed, whereas petiole elongation is promoted under the shade. However, the mechanisms that control these responses are largely unclear. Here, we demonstrated that both auxin and brassinosteroid (BR) are required for the normal leaf responses to shade. The microarray analysis of leaf blades and petioles treated with end-of-day far-red light (EODFR) revealed that almost half of the genes induced by the treatment in both parts were previously identified as auxin-responsive genes. Likewise, BR-responsive genes were overrepresented in the EODFR-induced genes. Hence, the auxin and BR responses were elevated by EODFR treatment in both leaf blades and petioles, although opposing growth responses were observed in these two parts. The analysis of the auxin-deficient doc1/big mutant and BR-deficient rot3/cyp90c1 mutant further indicates that auxin and BR were equally required for the normal petiole elongation response to the shade stimulus. In addition, the spotlight irradiation experiment revealed that phytochrome in leaf blades but not that in petioles regulated petiole elongation, which was probably mediated through regulation of the auxin/BR responses in petioles. On the basis of these findings, we conclude that auxin and BR cooperatively promote petiole elongation in response to the shade stimulus under the control of phytochrome in the leaf blade.
Project description:Development of a flat structure of leaves depend on active expansion of leaf blades mediated by cell proliferation. The angustifolia3 (an3) mutants of Arabidopsis thaliana are defective in cell proliferation in leaf primorida. AN3 encodes a transcription coactivator and interacts with a putative transcription factor AtGRF5. To investigate how AN3 control cell proliferation, we compared gene expression profiles between an3 and wild type. This analysis provide an insight into AN3-dependent cell proliferation pathway.
Project description:Plants grown under a canopy recognize changes in light quality and modify their growth patterns; this modification is known as shade avoidance syndrome. In leaves, leaf blade expansion is suppressed, whereas petiole elongation is promoted under the shade. However, the mechanisms that control these responses are largely unclear. Here, we demonstrated that both auxin and brassinosteroid (BR) are required for the normal leaf responses to shade. The microarray analysis of leaf blades and petioles treated with end-of-day far-red light (EODFR) revealed that almost half of the genes induced by the treatment in both parts were previously identified as auxin-responsive genes. Likewise, BR-responsive genes were overrepresented in the EODFR-induced genes. Hence, the auxin and BR responses were elevated by EODFR treatment in both leaf blades and petioles, although opposing growth responses were observed in these two parts. The analysis of the auxin-deficient doc1/big mutant and BR-deficient rot3/cyp90c1 mutant further indicates that auxin and BR were equally required for the normal petiole elongation response to the shade stimulus. In addition, the spotlight irradiation experiment revealed that phytochrome in leaf blades but not that in petioles regulated petiole elongation, which was probably mediated through regulation of the auxin/BR responses in petioles. On the basis of these findings, we conclude that auxin and BR cooperatively promote petiole elongation in response to the shade stimulus under the control of phytochrome in the leaf blade. The WT seedlings were grown for 19 days under continuous white light condition before experimental treatment with three light conditions. Seedlings were either maintained in white light for 2 h (WL), incubated in the dark condition for 2 h (D), or experienced a pulse irradiation of FR light before incubated in the dark condition for 2 h (FRD). Total RNAs were separately prepared from leaf blades and petioles after each light treatment. Three independent biological replicates were used.
Project description:The 5th and 6th leaf blades of the rice Os-LBD37 overexpressor line RK16331-13 and the empty vector control line FOX3 were examined. LBD37 belongs to the plant- specific LOB- (Lateral Organ Boundary) domain family proteins first characterized in Arabidopsis. Results point towards an involvement of the rice LBD37 (OsLBD37) ortholog of Arabidopsis in nitrogen metabolism- and senescence- related processes. Hygromycin- resistant rice Os-LBD37 overexpressor and empty vector control plants were grown in hydroponic culture system. The sampling date of the leaf blades of RK16331-13 LBD37 overexpressor plants and the empty vector control was determined according to the emergence of the 8th leaf blade. Three independent hybridizations were performed for line RK16331-13 and the empty vector control line.
Project description:The 5th and 6th leaf blades of the rice Os-LBD37 overexpressor line RK16331-13 and the empty vector control line FOX3 were examined. LBD37 belongs to the plant- specific LOB- (Lateral Organ Boundary) domain family proteins first characterized in Arabidopsis. Results point towards an involvement of the rice LBD37 (OsLBD37) ortholog of Arabidopsis in nitrogen metabolism- and senescence- related processes.