Phytochrome-interacting factor-like protein OsPIL15 integrates light and gravitropism to regulate tiller angle in rice
Rice phytochrome-interacting factor-like protein OsPIL15 regulates tiller angle through light and gravity signals in rice.
Tiller angle of cereal crops is a key agronomic trait that contributes to grain production. An understanding of how tiller angle is controlled is helpful for achieving ideal plant architecture to improve grain yield. Phytochrome-interacting factors (PIFs) are known to regulate seed germination, seedling skotomorphogenesis, shade avoidance, and flowering in Arabidopsis thaliana. Here, we report that OsPIL15 is, indeed, a rice PIF that negatively regulates tiller angle. Dominant-negative OsPIL15 plants displayed a larger tiller angle, which was associated with reduced shoot gravitropism. Phytochrome B (phyB) is the main photoreceptor perceiving the low red:far-red ratio of shade light. Compared with wild-type rice plants, loss-of-function phyB plants and OsPIL15-overexpressing plants showed smaller tiller angles and enhanced shoot gravitropism. In addition, more OsPIL15 protein accumulated in phyB plants than in wild-type plants. Light regulates the level of the OsPIL15 protein negatively, depending on phyB partially. We propose that OsPIL15 integrates light and gravity signals to regulate tiller angle in rice.
KeywordsOsPIL15 Tiller angle Phytochrome Gravitropism
This work was supported by the National Transgenic Science and Technology Program (2016ZX08010-002) and the National Basic Research Program (973 Program 2013CBA01403). We are grateful to Dr. Jiayang Li for the vector pVKmp-lib and Dr. Jianmin Wan for rice phyB seeds.
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