高粱穀粒品質與澱粉生合成SSIIa、Wx、Ae1基因之關聯分析

Abstract

高粱(Sorghum bicolor)穀粒富含澱粉，其澱粉品質為評斷高粱穀粒優劣的主要項目，澱粉品質進而影響營養價值與加工的應用性。本研究採用7個高粱品種，分析品種間澱粉相關性狀(澱粉與直鏈澱粉含量、千粒重、榖粒長、榖粒寬與澱粉糊化特性)差異性，並選定澱粉生合成路徑Soluble starch synthases (SSIIa)、Granule-bound starch synthase (Wx)與Starch branching enzyme (Ae1)三個候選基因，進行序列多型性的分析，最後以關聯分析(association analysis)方法尋找與表型具關聯性的等位基因。結果顯示SSIIa序列上具有9個多型性位點，而Wx 共具有7個多型性位點，其中一些位點與澱粉糊化特性有相關。Ae1增幅的兩片段上具有29個多型性位點。Ae1增幅片段的單一核苷酸多型性(single nucleotide polymorphisms, SNP)及插入與缺失(insertion and deletion, InDel)片段與澱粉糊化起始溫度(gelatinization temperature)相關，平均溫度相差9.4℃。在Ae1內插子區域的SNP與直鏈澱粉含量之含量具關聯性(p<0.05)，腺嘌呤鹼基 (adenine base)的缺失導致直鏈澱粉含量甚低。綜合實驗結果，序列多型性的鑑定可說明高粱澱 粉相關特性的遺傳變異。

Sorghum is rich in starch content, the starch quality contributes to its nutritional value and processing attributes tremendously. In this study, seven varieties of soghum were collected for analysis in their starch content, amylose content, pasting properties, thousand grain weight, and grain size. To identify the correlation of gene variation and the phenotype in starch content, genes including soluble starch synthases (SSIIa), granule-bound starch synthase (Wx) and starch branching enzyme (Ae1) were chosen for association analysis using statistical software. A total of 9 polymorphisms in SSIIa and 7 polymorphisms in Wx were identified, which were greatly associated with starch pasting properties. A total of 29 polymorphisms in two fragments of Ae1 were identified. Single nucleotide polymorphisms(SNP) and InDel in Ae1 were found associated with gelatinization temperature, which with a difference of 9.4℃ in gelatinization temperature. One SNP in non-coding region of Ae1 were found associated with amylase content (p<0.05), inferred deletion of a adenine base would cause a decrease in non-branching starch. The polymorphism we identified in this study may provide a genetic explanation to variation in sorghum starch properties.