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UNBRANCHED3 regulates branching by modulating cytokinin biosynthesis and signaling in maize and rice
Author(s) -
Du Yanfang,
Liu Lei,
Li Manfei,
Fang Shuang,
Shen Xiaomeng,
Chu Jinfang,
Zhang Zuxin
Publication year - 2017
Publication title -
new phytologist
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 3.742
H-Index - 244
eISSN - 1469-8137
pISSN - 0028-646X
DOI - 10.1111/nph.14391
Subject(s) - panicle , cytokinin , oryza sativa , biology , meristem , mutant , inflorescence , gene , botany , microbiology and biotechnology , genetics , auxin
SummaryUNBRANCHED 3 ( UB 3 ), a member of the SQUAMOSA promoter binding protein‐like ( SPL ) gene family, regulates kernel row number by negatively modulating the size of the inflorescence meristem in maize. However, the regulatory pathway by which UB 3 mediates branching remains unknown. We introduced the UB 3 into rice and maize to reveal its effects in the two crop plants, respectively. Furthermore, we performed transcriptome sequencing and protein‐ DNA binding assay to elucidate the regulatory pathway of UB 3 . We found that UB 3 could bind and regulate the promoters of LONELY GUY 1 ( LOG 1 ) and Type‐A response regulators ( ARR s ), which participate in cytokinin biosynthesis and signaling. Overexpression of exogenous UB 3 in rice ( Oryza sativa ) dramatically suppressed tillering and panicle branching as a result of a greater decrease in the amount of active cytokinin. By contrast, moderate expression of UB 3 suppressed tillering slightly, but promoted panicle branching by cooperating with SPL genes, resulting in a higher grain number per panicle in rice. In maize ( Zea mays ) ub3 mutant with an increased kernel row number, UB 3 showed a low expression but cytokinin biosynthesis‐related genes were up‐regulated and degradation‐related genes were down‐regulated. These results suggest that UB 3 regulates vegetative and reproductive branching by modulating cytokinin biosynthesis and signaling in maize and rice.