| Rice genetic transformation is essential for rice molecular breeding and functional analysis of rice genes. The Agrobacterium-mediated transformation system with japonica rice has been well-established. However, transformation efficiency for indica rice is very low, which severely affect functional analysis of many important rice genes. In this study, 93-11, a representative indica variety, was used in this study. An efficient transformation system for indica variety 93-11 has been established by means of optimizing nutrient medium and the transformation protocol, which is able to generate transgenic rice plants within 40 days.Jasmonate (JA) is a new class of plant hormone, which regulates many plant developmental and growth processes, and mediate plant responses to abiotic and biotic stresses. The F-box protein coronatine insensitive 1 (COI1), as a key regulator in JA signal pathway, participates in JA-regulated plant growth and leaf senescence. Leaf senescence can be induced by many developmental signals and environmental stresses. JAs induce leaf senescence in many plant species. However, the molecular mechanism for JA-induced leaf senescence remains unclear. In this study, we identified Ribulose bisphosphate carboxylase oxygenase activase (RCA) as the COI1-dependent JA-repressed protein. Molecular, genetic and physiological analyses indicated that RCA degradation was related with JA-induced leaf senescence. The mutation of RCA led to common senescence-related symptoms in rca-1 and rca-2 mutants. The JA-treated WT leaves presented severely senescence and exhibited severe degradation of RCA whereas the leaves of coil-1 mutant were less affected, indicating that the COI1-dependent JA-repression of RCA played an important role in JA-induced leaf senescence. |
