Fan Tian, Yang Wu, Zeng Xuan, Xu Xinlan, Xu Yanling, Fan Xiaorong, Luo Ming, Tian Changen, Xia Kuaifei, Zhang Mingyong
School of Life Sciences, Guangzhou University, Guangzhou, China.
Innovation Academy for Seed Design, Guangdong Provincial Key Laboratory of Applied Botany, Key Laboratory of South China Agricultural Plant Molecular Analysis and Genetic Improvement, South China Botanical Garden, Chinese Academy of Sciences, Guangzhou, China.
Front Plant Sci. 2020 Jun 4;11:588. doi: 10.3389/fpls.2020.00588. eCollection 2020.
Enhancing nitrogen (N) use efficiency is a potential way to reduce excessive nitrogen application and increase yield. Autophagy is a conserved degradation system in the evolution of eukaryotic cells and plays an important role in plant development and stress response. Autophagic cores have two conjugation pathways that attach the product of autophagy-related gene 8 (ATG8) to phosphatidylethanolamine (PE) and ATG5 to ATG12, respectively, which then help with vesicle elongation and enclosure. Rice has six genes, which have not been functionally confirmed so far. We identified the rice gene and characterized its role in N remobilization to affect grain quality by generating transgenic plants with its over-expression and knockdown. Our study confirmed the autophagy activity of OsATG8b through the complementation of the yeast autophagy-defective mutant and by observation of autophagosome formation in rice. The autophagy activity is higher in -OE lines and lower in -RNAi than that in wild type (ZH11). N pulse-chase analysis revealed that -OE plants conferred higher N recycling efficiency to grains, while -RNAi transgenic plants exhibited lower N recycling efficiency and poorer grain quality. The autophagic role of was experimentally confirmed, and it was concluded that OsATG8b-mediated autophagy is involved in N recycling to grains and contributes to the grain quality, indicating that OsATG8b may be a potential gene for molecular breeding and cultivation of rice.
提高氮素利用效率是减少过量施氮并提高产量的一种潜在途径。自噬是真核细胞进化过程中保守的降解系统，在植物发育和胁迫响应中发挥重要作用。自噬核心有两条缀合途径，分别将自噬相关基因8（ATG8）的产物连接到磷脂酰乙醇胺（PE）上，以及将ATG5连接到ATG12上，进而帮助囊泡伸长和包裹。水稻有六个基因，目前尚未得到功能确认。我们鉴定了水稻基因，并通过构建其过表达和敲低的转基因植株，来表征其在氮素再利用中对籽粒品质的影响。我们的研究通过酵母自噬缺陷突变体的互补以及水稻中自噬体形成的观察，证实了OsATG8b的自噬活性。与野生型（ZH11）相比，过表达系的自噬活性更高，而RNA干扰系的自噬活性更低。氮脉冲追踪分析表明，过表达植株赋予籽粒更高的氮循环效率，而RNA干扰转基因植株表现出较低的氮循环效率和较差的籽粒品质。通过实验证实了该基因的自噬作用，并得出结论：OsATG8b介导的自噬参与了籽粒中的氮循环并有助于籽粒品质，这表明OsATG8b可能是水稻分子育种和栽培的一个潜在基因。
