摘要
Grain size is one of the key agronomic traits that determine grain yield in crops. However, the mechanisms underlying grain size control in crops remain elusive. Here we demonstrate that the OsMKKK10-OsMKK4- OsMAPK6 signaling pathway positively regulates grain size and weight in rice. In rice, loss of OsMKKKIO function results in small and light grains, short panicles, and semi-dwarf plants, while overexpression of constitutively active OsMKKK10 （CA-OsMKKK10） results in large and heavy grains, long panicles, and tall plants. OsMKKK10 interacts with and phosphorylates OsMKK4. We identified an OsMKK4 gain-of-func- tion mutant （large11-1D）that produces large and heavy grains. OsMKK4A227T encoded by the large11-1D allele has stronger kinase activity than OsMKK4. Plants overexpressing a constitutively active form of OsMKK4 （OsMKK4oDD） also produce large grains. Further biochemical and genetic analyses revealed that OsMKKK10, OsMKK4, and OsMAPK6 function in a common pathway to control grain size. Taken together, our study establishes an important genetic and molecular framework for OsMKKK10-OsMKK4- OsMAPK6 cascade-mediated control of grain size and weight in rice.
Grain size is one of the key agronomic traits that determine grain yield in crops. However, the mechanisms underlying grain size control in crops remain elusive. Here we demonstrate that the OsMKKK10-OsMKK4- OsMAPK6 signaling pathway positively regulates grain size and weight in rice. In rice, loss of OsMKKKIO function results in small and light grains, short panicles, and semi-dwarf plants, while overexpression of constitutively active OsMKKK10 （CA-OsMKKK10） results in large and heavy grains, long panicles, and tall plants. OsMKKK10 interacts with and phosphorylates OsMKK4. We identified an OsMKK4 gain-of-func- tion mutant （large11-1D）that produces large and heavy grains. OsMKK4A227T encoded by the large11-1D allele has stronger kinase activity than OsMKK4. Plants overexpressing a constitutively active form of OsMKK4 （OsMKK4oDD） also produce large grains. Further biochemical and genetic analyses revealed that OsMKKK10, OsMKK4, and OsMAPK6 function in a common pathway to control grain size. Taken together, our study establishes an important genetic and molecular framework for OsMKKK10-OsMKK4- OsMAPK6 cascade-mediated control of grain size and weight in rice.
基金
This work was supported by grants from the National Basic Research Program of China （2016YFD0100402
2016YFD0100501
2017YFD0101701
2013CBA01401）, the National Natural Science Foundation of China （91735302
31771340
31500976
91535203
31425004
31400249）, the Chinese Academy of Sciences （XDA08020108）, the Ministry of Agriculture of China （2014ZX08009-003）, and the strategic pdodty research program ＂Molecular Mechanism of Plant Growth and Development＂ （XDBP401）.
