新型香稻渝恢2103香味分子遗传特性分析

Molecular Genetic Characteristics of Fragrance in a New Fragrant Rice Variety Yuhui 2103

香味是优良稻米品质的重要衡量标准之一,2-乙酰-1-吡咯啉(2AP)是最主要的香味物质,然而2AP生物合成机理至今仍未确凿。本研究筛选了与2AP生物合成密切相关的甜菜碱脱氢酶2基因(Badh2)在30份水稻材料中的3种突变类型,从中发现1份新的香稻材料渝恢2103,该材料Badh2基因序列编码区无突变,遗传分析显示渝恢2103与badh2-E7突变型香稻宜香1B香味基因不等位,与非香稻杂交F2香与非香分离比接近9∶7,与香稻杂交F2香与非香分离比接近7∶9,表明渝恢2103的香味受多基因控制。进一步利用实时荧光定量PCR技术(qRT-PCR)比较了与2AP生物合成相关基因在日本晴、渝恢2103和宜香1B的表达情况,结果显示,Badh2基因在日本晴和渝恢2103中表达差异不大,但在宜香1B中表达量异常高;多数脯氨酸与谷氨酸代谢途径相关基因在宜香1B中的表达水平显著高于日本晴和渝恢2103;推测宜香1B的2AP合成同时受Badh2基因以及脯氨酸与谷氨酸代谢途径相关基因的影响;渝恢2103香味形成可能与这些基因无必然联系。渝恢2103特殊的遗传特性可能为水稻香味形成机理研究提供新的突破点。

A major component2-acetyl-1-pyrroline(2AP)in fragrance is one of the important indices of high-quality rice,however,the biosynthetic pathway of2AP has not been demonstrated clearly.The betaine aldehyde dehydrogenase2(BADH2)is considered to be closely related to2AP biosynthesis.In this study,three mutations in Badh2gene were screened from thirty rice varieties and a new fragrant rice variety Yuhui2103was discovered.The new variety has no mutation in the coding region of Badh2gene and the Badh2allele of Yuhui2103can complement the defect of the badh2-E7allele in Yixiang1B.From crosses between Yuhui2103and non-fragrant varieties the segregating ratios of F2fragrant to non-fragrant individuals were9:7,while from crosses between Yuhui2103and fragrant varieties the segregating ratios of F2fragrant to non-fragrant individuals were7:9,indicating that fragrance of Yuhui2103is not controlled by only one gene.Furthermore,expression patterns of genes involved in2AP biosynthesis were examined by the quantitative real-time PCR(qRT-PCR)in Nipponbare,Yuhui2103,and Yixiang1B.There was no significant difference in transcription level of Badh2in Nipponbare and Yuhui2103,however,the transcription level of Badh2in Yixiang1B was unexpectedly high.The expression levels of most of the genes involved in proline and glutamatic acid metabolism were significantly higher in Yixiang1B than that in Nipponbare and Yuhui2103.It is proposed that2AP biosynthesis in Yixiang1B is both influenced by Badh2and the genes involved in proline and glutamatic acid metabolism,however,there is no necessary relationship between these genes and the fragrance of Yuhui2103.The novel genetic characters of Yuhui2103may bring new breakthrough to the study of fragrance formation mechanism in rice.