The Ubiquitin Receptor DA1 Regulates Seed and Organ Size by Modulating
the Stability of the Ubiquitin-Specific Protease UBP15/SOD2 in
Arabidopsis |
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| Authors: | Liang Du Na Li Liangliang Chen Yingxiu Xu Yu Li Yueying Zhang Chuanyou Li Yunhai Li |
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| Affiliation: | aState Key Laboratory of Plant Cell and Chromosome Engineering, Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, Beijing 100101, China;bUniversity of Chinese Academy of Sciences, Beijing 100039, China;cState Key Laboratory of Plant Genomics, Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, Beijing 100101, China |
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| Abstract: | Although the control of organ size is a fundamental question in developmentalbiology, little is known about the genetic and molecular mechanisms that determinethe final size of seeds in plants. We previously demonstrated that the ubiquitinreceptor DA1 acts synergistically with the E3 ubiquitin ligases DA2 and ENHANCER1 OFDA1 (EOD1)/BIG BROTHER to restrict seed growth in Arabidopsisthaliana. Here, we describe UBIQUITIN-SPECIFIC PROTEASE15 (UBP15),encoded by SUPPRESSOR2 OF DA1 (SOD2), which actsmaternally to regulate seed size by promoting cell proliferation in the integumentsof ovules and developing seeds. The sod2/ubp15 mutants form smallseeds, while overexpression of UBP15 increases seed size ofwild-type plants. Genetic analyses indicate that UBP15 functionsantagonistically in a common pathway with DA1 to influence seedsize, but does so independently of DA2 and EOD1.Further results reveal that DA1 physically associates with UBP15 in vitro and in vivoand modulates the stability of UBP15. Therefore, our findings establish a genetic andmolecular framework for the regulation of seed size by four ubiquitin-relatedproteins DA1, DA2, EOD1, and UBP15 and suggest that they are promising targets forincreasing seed size in crops. |
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