AUTHOR=Zhou Dan , Shen Weifeng , Cui Yuchao , Liu Yuqin , Zheng Xijun , Li Yan , Wu Minliang , Fang Shanru , Liu Chunhong , Tang Ming , Yi Yin , Zhao Mingfu , Chen Liang 

TITLE=APICAL SPIKELET ABORTION (ASA) Controls Apical Panicle Development in Rice by Regulating Salicylic Acid Biosynthesis

JOURNAL=Frontiers in Plant Science

VOLUME=12

YEAR=2021

URL=https://www.frontiersin.org/journals/plant-science/articles/10.3389/fpls.2021.636877

DOI=10.3389/fpls.2021.636877

ISSN=1664-462X

ABSTRACT=<p>Panicle degradation causes severe yield reduction in rice. There are two main types of panicle degradation: apical spikelet abortion and basal degeneration. In this study, we isolated and characterized the apical panicle abortion mutant <italic>apical spikelet abortion</italic> (<italic>asa</italic>), which exhibits degeneration and defects in the apical spikelets. This mutant had a pleiotropic phenotype, characterized by reduced plant height, increased tiller number, and decreased pollen fertility. Map-based cloning revealed that <italic>OsASA</italic> encodes a boric acid channel protein that showed the highest expression in the inflorescence, peduncle, and anther. RNA-seq analysis of the <italic>asa</italic> mutant vs wild-type (WT) plants revealed that biological processes related to reactive oxygen species (ROS) homeostasis and salicylic acid (SA) metabolism were significantly affected. Furthermore, the <italic>asa</italic> mutants had an increased SA level and H<sub>2</sub>O<sub>2</sub> accumulation in the young panicles compared to the WT plants. Moreover, the SA level and the expression of <italic>OsPAL3</italic>, <italic>OsPAL4</italic>, and <italic>OsPAL6</italic> genes (related to SA biosynthesis) were significantly increased under boron-deficient conditions in the <italic>asa</italic> mutant and in <italic>OsASA-</italic>knockout plants. Collectively, these results suggest that the boron distribution maintained by <italic>OsASA</italic> is required for normal panicle development in a process that involves modulating ROS homeostasis and SA biosynthesis.</p>