自噬（autophagy）是发生在细胞内的“Self eating”现象，其主要的生理功能是将胞质中的大分子物质（如蛋白质等）和一些细胞内源性底物（包括由于生理或病理原因引起的衰老、破损的细胞器）在单位膜包裹的自噬体中大量降解，实现再循环，以维持细胞自身的稳定。这个过程对于细胞成分更新、逆境条件下营养成份的再利用等是至关重要的。它在植物正常生长发育与适应环境协迫中发挥重要作用，自噬过程涉及众多基因的参与。
中科院华南植物园植物生理生化研究组夏快飞等科研人员通过对水稻基因组的分析，全面系统地鉴定了水稻自噬过程中的全部基因。水稻基因组中包含至少33个自噬相关基因，它们可以归属于13个亚家族，参与整个水稻的自噬过程。研究人员还通过表达谱分析了这些基因在激素处理、氮饥饿与逆境下的表达反应规律。
该研究进展将有助于针对这些基因开展更深入的研究。相关论文已在线发表在《DAN研究》（DNA Research）上。
该研究得到国家自然科学基金与中国科学院植物资源保护与可持续利用重点实验室青年基金的资助。(生物谷 Bioon.com)
doi:10.1093/dnares/dsr024
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Genome-Wide Identification, Classification, and Expression Analysis of Autophagy-Associated Gene Homologues in Rice (Oryza sativa L.)
Kuaifei Xia, Tao Liu, Jie Ouyang, Ren Wang, Tian Fan, and Mingyong Zhang
Autophagy is an intracellular degradation process for recycling macromolecules and organelles. It plays important roles in plant development and in response to nutritional demand, stress, and senescence. Organisms from yeast to plants contain many autophagy-associated genes (ATG). In this study, we found that a total of 33 ATG homologues exist in the rice [Oryza sativa L. (Os)] genome, which were classified into 13 ATG subfamilies. Six of them are alternatively spliced genes. Evolutional analysis showed that expansion of 10 OsATG homologues occurred via segmental duplication events and that the occurrence of these OsATG homologues within each subfamily was asynchronous. The Ka/Ks ratios suggested purifying selection for four duplicated OsATG homologues and positive selection for two. Calculating the dates of the duplication events indicated that all duplication events might have occurred after the origin of the grasses, from 21.43 to 66.77 million years ago. Semi-quantitative RT–PCR analysis and mining the digital expression database of rice showed that all 33 OsATG homologues could be detected in at least one cell type of the various tissues under normal or stress growth conditions, but their expression was tightly regulated. The 10 duplicated genes showed expression divergence. The expression of most OsATG homologues was regulated by at least one treatment, including hormones, abiotic and biotic stresses, and nutrient limitation. The identification of OsATG homologues showing constitutive expression or responses to environmental stimuli provides new insights for in-depth characterization of selected genes of importance in rice.
