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SMALL GRAIN 1 , which encodes a mitogen‐activated protein kinase kinase 4, influences grain size in rice
Author(s) -
Duan Penggen,
Rao Yuchun,
Zeng Dali,
Yang Yaolong,
Xu Ran,
Zhang Baolan,
Dong Guojun,
Qian Qian,
Li Yunhai
Publication year - 2014
Publication title -
the plant journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 3.058
H-Index - 269
eISSN - 1365-313X
pISSN - 0960-7412
DOI - 10.1111/tpj.12405
Subject(s) - panicle , protein kinase a , mutant , biology , grain size , green fluorescent protein , microbiology and biotechnology , kinase , gene , genetics , agronomy , materials science , metallurgy
Summary Although grain size is one of the most important components of grain yield, little information is known about the mechanisms that determine final grain size in crops. Here we characterize rice small grain1 ( smg1 ) mutants, which exhibit small and light grains, dense and erect panicles and comparatively slightly shorter plants. The short grain and panicle phenotypes of smg1 mutants are caused by a defect in cell proliferation. The smg1 mutations were identified, using a map‐based cloning approach, in mitogen‐activated protein kinase kinase 4 ( Os MKK 4 ). Relatively higher expression of Os MKK 4/ SMG 1 was detected in younger organs than in older ones, consistent with its role in cell proliferation. Green fluorescent protein ( GFP )–Os MKK 4/ SMG 1 fusion proteins appear to be distributed ubiquitously in plant cells. Further results revealed that Os MKK 4 influenced brassinosteroid ( BR ) responses and the expression of BR ‐related genes. Thus, our findings have identified Os MKK 4 as a factor for grain size, and suggest a possible link between the MAPK pathways and BR s in grain growth.