萵苣品種鑑定及莖伸長期轉錄體之資訊分析

Abstract

萵苣 (Lactuca sativa L.) 為世界重要蔬菜之一，商業品種眾多。由於品種偷竊與育種者權日益受到重視，使種苗生產者關注品種鑑別及純度問題，農民亦期望種植在高溫環境下晚抽苔之品種，因其具有較高的商業價值。因此，利用多型性分子標誌鑑別商業品種以及了解高溫誘導萵苣抽苔的機制有其重要性。本研究利用去氧核醣核酸分子標誌 (deoxyribonucleic acid molecular marker) 簡單重複序列 (simple sequence repeats, SSRs) 鑑定萵苣品種。自82個SSR選出38個具有多型性者測試，結果顯示利用5個分子標誌即可有效率地鑑別25個萵苣商業品種，且基因型幾乎皆為同質結合。此外，李 (2015) 建立了萵苣早抽苔品種 ‘直立萵’ 及晚抽苔 ‘福山’在莖長5 cm時之莖頂轉錄體，並以Kyoto Encyclopedia of Genes and Genomes (KEGG) 分析；本研究進一步以 ContigView 平台比較與分析該莖頂轉錄體，結果顯示，LsCNGC4a 可能在高溫誘導抽苔的機制中扮演重要角色，且與離層酸作用、過氧化物產生、鈣離子訊息傳遞基因及開花抑制基因有關；在 ‘直立萵’ 莖伸長階段，LsFLCa、LsFLCb、LsHIPP3 以及LsOXS3 的表現量下降，可能與熱休克反應及離層酸訊息傳導路徑有關，導致該品種在高溫環境提早抽苔之外表型。

Lettuce (Lactuca sativa L.) is one of the most important vegetables in the world, which many commercial cultivars had developed. Because the concern of cultivar stealing and breeders’ right, seed producers pay attention to identify the purity of cultivars and seeds. On the other hands, farmers prefer cultivars with lately-flowering phenotype under high temperature which have higher commercial market value. Therefore, distinguishing commercial cultivars by using highly-polymorphic molecular markers and understanding the mechanism of heat-induced bolting in lettuce are important. In this study, the deoxyribonucleic (DNA) marker, simple sequence repeats (SSRs), was used to identify lettuce cultivars. From 82 SSRs, 38 with polymorphism were selected out to identify 25 commercial lettuce cultivars. Only 5 SSRs were required to identify 25 cultivars efficiently. Lee (2015) had developed stem apical transcriptomes of the early- bolting cultivar ‘Jhih Li Wo’ and the lately- bolting ‘Fu San’ of lettuce when stem elongated to 5 cm under high temperature. Lee analyzed these transcriptomes by Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway. In this study, these transcriptomes were analyzed instead through the ContigViews system and comparative networks were generated. The results showed LsCNGC4a might be an important gene which plays a role in heat-induced bolting and is involved with abscisic acid (ABA) function, reactive oxidative species (ROS) production, calcium signaling genes, and several negatively-regulated flowering genes. The decrease of LsFLCa, LsFLCb, LsHIPP3 and LsOXS3 expression might connect to the heat shock response (HSR) and ABA signaling pathway, leading to the early bolting phenotype of ‘Jhih Li Wo’.