香稻Badh2基因单倍型及香气成分2-乙酰-1-吡咯啉代谢通路的研究进展

Research Advances of Haplotype Variation at Badh2 Gene and 2-Acetyl-1-pyrroline Bi osynthetic Pathway in Aromatic Rice

香米因其具有独特的香味,长期以来深受国际市场青睐。我国香稻种植历史悠久,香稻资源丰富,但缺乏高端优质香米品牌。当前消费者对优质香米的需求不断加大,进而加快了我国优质香稻的育种进程。稻米香味主要由编码甜菜碱醛脱氢酶基因Badh2控制,该基因功能突变能够导致稻米香气成分2-乙酰-1-吡咯啉(2AP)的积累。随着水稻功能基因组学的发展,香稻资源中Badh2基因单倍型得以深入挖掘,2AP生物合成通路被初步解析,它们将进一步加快香稻育种的进程。综述了目前在香稻资源中发现的19种Badh2基因单倍型,重点分析不同类型单倍型的地域分布特性,比较不同单倍型之间的2AP含量;同时阐述2AP生物合成通路涉及的谷氨酸-脯氨酸代谢途径和多胺代谢途径研究现状,总结香稻籽粒中2AP的分布特征,并对目前两种籽粒2AP积累的理论机制进行比较分析,提出利用多组学手段从籽粒动态发育过程研究2AP生物合成通路变化特性的策略,以期为香稻资源基因利用和籽粒2AP特异富集香稻品种的培育提供参考。

Aromatic rice has long been favored by the world rice trade because of its pleasant scent.China has a long history of aromatic rice cultivation and diverse aromatic rice accessions.However,there is a real lack of top aromatic rice brands.Nowadays,there is an increasing demand for good-quality aromatic rice,leading to speed up the breeding process of high quality of aromatic rice varieties.The Badh2,encoding betaine aldehyde dehydrogenase gene,is the major genetic basis of fragrance in rice.The loss-of-function alleles of Badh2 accounts for accumulation of 2-acetyl-1-pyrroline(2AP),which is widely regarded as the main compound responsible for the characteristic aroma.With the development of rice functional genomics,the Badh2 gene haplotypes in aromatic rice resources have been deeply explored and the biosynthesis pathway of 2AP has been preliminarily analyzed,which will speed up the process of aromatic rice breeding.This review focused on 19 Badh2 gene haplotypes which were found in aromatic rice accessions.The geographic locations of different types of haplotypes were mainly analyzed and the correlation between these haplotypes and 2AP concentrations were compared.The research advances of glutamate-proline metabolic pathway and polyamine metabolic pathway involved in 2AP biosynthesis pathway were demonstrated.Meanwhile,the 2AP distribution characteristics in aromatic rice grains were summarized.Two theoretical mechanisms of 2AP accumulation in grains were compared and a strategy to study the 2AP biosynthesis pathway changes at various grain developmental stages by multi-omics methods was proposed,with a view to serve as an inspiration for genetic utilization of aromatic rice resources and breeding of rice varieties with 2AP specific enrichment.