甜瓜果實性狀及白粉病抗性之數量性狀基因座定位

Mapping quantitative trait loci for fruit traits and powdery mildew resistance in melon (Cucumis melo L.)

王毓華(Yu-Hua Wang)

指導教授 ： 羅筱鳳

共同指導教授 ： 胡凱康(Kae-Kang Hwu)

國立臺灣大學/生物資源暨農學院/園藝暨景觀學系/博士(2016年)

https://doi.org/10.6342/NTU201602682

摘要

甜瓜(cucumis melo L.)為高經濟價值作物，其市場價值決定於果實性狀，因此了解與果實品質相關的性狀，將有助於高品質甜瓜之育種。然而，甜瓜栽培過程中常面臨白粉病的威脅，若能將抗病性導入甜瓜栽培品種，將可提高甜瓜生產的安全性。本研究利用15組簡單重複區間序列(inter simple sequence repeat, ISSR)分子標誌進行遺傳歧異度分析，將24個不同類型的甜瓜自交系分melo亞種(ssp. melo)和agrestis亞種(ssp. agrestis)，分別從中選出TARI-08874 (Cucumis melo ssp. melo)和‘Bai-li-gua’ (C. melo ssp. agrestis)兩個自交系，建立484個單株之F2族群，並利用80個簡單重複序列(simple sequence repeat, SSR)分子標誌建構甜瓜遺傳連鎖圖譜，其可分為12個連鎖群、1個次要連鎖群以及2個未連鎖的SSR分子標誌，總長度為632.4 cM，分子標誌間的平均遺傳距離為8.1 cM。本連鎖圖譜並做為後續甜瓜重要果實園藝性狀及抗白粉病性狀之數量性狀基因座(quantitative trait loci, QTLs)定位研究。
各果實相關性狀(果重、果徑、果寬、果肉厚、果皮顏色、果肉顏色、網紋密度及網紋寬度)於兩個試驗中，兩親本TARI-08874和‘Bai-li-gua’間均有顯著差異。其中，果實大小相關性狀(果重、果徑、果寬和果肉厚) 之間具有高度相關性，網紋性狀(網紋密度和網紋寬度)間也有顯著性相關，但果皮顏色和果肉顏色間無相關。進一步分析果實品質相關性狀之QTLs，在8個果實品質相關性狀中偵測到21個數量性狀基因座，其中11個QTLs與前人研究結果一致，有10個新檢測出的QTL，而有6個QTLs在兩個試驗均有測出。自甜瓜果實大小相關性狀偵測出10個QTLs，果實重量主要受到果徑和果肉厚的影響，並由QTLs相關位置推測，第5和第11連鎖群上應具有決定果實大小之重要遺傳訊息。在第4連鎖群上偵測到一個與果皮顏色有關之QTL，並且與SSR分子標誌CMBR154間具有緊密連鎖關係，未來或可應用於分子輔助育種。與果肉顏色相關的QTL有兩個，分別位於第5和第8連鎖群上。果皮網紋性狀，尤其是網紋寬度是本研究重點，兩次試驗皆偵測出與網紋密度和網紋寬度有關的QTLs4個，此為甜瓜網紋寬度QTL之第一篇研究報告。
白粉病(Podosphaera xanthii)為甜瓜栽培之重要病害，本研究利用一組甜瓜白粉病生理小種之鑑別品種，分別於臺南和臺中試區，偵測到發生於田間之甜瓜白粉病主要生理小種為P. xanthii race 1和race 5，但是可能還有其他未知的生理小種存在。自57個自交系中選出24個自交系對P. xanthii race 1具有抗性，但僅有2個自交系對P. xanthii race 5具有抗性。自交系TARI-08874對感病自交系‘Bai-li-gua’的抗病性為一對顯性基因所控制。以TARI-08874和‘Bai-li-gua’所建立的F2族群，進行抗病性之數量性狀基因座定位，在第2連鎖群(LG2)偵測到1個QTL，該QTL與SSR分子標誌CMBR120間具有緊密連鎖關係。

關鍵字

甜瓜 ； 簡單重複區間序列 ； 簡單重複序列 ； 數量性狀基因座 ； 遺傳相關性 ； 果實大小 ； 果色 ； 果肉顏色 ； 果皮網紋白粉病 ； 遺傳分析 ； 數量性狀基因座

並列摘要

Melon is a crop of economic importance and the fruit characters determine consumer’s satisfaction and the market value. The genetic information of fruit quality-related characters is a prerequisite for the breeding of high quality melon. Furthermore, powdery mildew is a limiting factor in melon production. To develop new cultivars for stable production of high-quality melons, the pyramiding of genes determining fruit traits and disease resistance is required. Twenty-four inbred lines of different types were screened for genetic diversity using fifteen inter simple sequence repeat (ISSR) primers. These inbred lines were grouped into two clusters based on ISSR markers. One inbred line of each cluster was selected and crossed to create two dependent F2 populations. One is TARI-08874 belonging to Cucumis melo ssp. melo, and another is ‘Bai-li-gua’ belonging to Cucumis melo ssp. agrestis. The combined F2 population containing 484 individuals from the cross of TARI-08874 and ‘Bai-li-gua’ were used to map the quantitative trait loci (QTLs) for fruit-related traits and powdery mildew resistance. The generated linkage map was consisted of twelve major linkage groups (LGs), one minor linkage group, and two unlinked markers, spanning 632.4 cM in total, with an average distance of 8.1 cM between flanking markers.
The correlations among eight essential fruit traits were analyzed and the quantitative trait loci (QTL) of fruit were identified over two trials conducted in different period. The evaluated fruit traits include fruit weight, fruit diameter, fruit length, flesh thickness, external color, flesh color, fruit net density and net width. The two parental lines, TARI-08874 (Cucumis melo ssp. melo) and ‘Bai-li-gua’ (C. melo ssp. agrestis) exhibited significant difference in all investigated traits (P < 0.05). There were high correlations among the fruit size-related traits, namely, fruit weight, fruit diameter, fruit length and flesh thickness. The two skin netting traits, netting density and netting width were highly correlated. However, the two coloration characters, external color and flesh color showed no correlation. The combined F2 population developed from TARI-08874 x ‘Bai-li-gua’ cross was used to map the QTLs involved in eight fruit traits over two trials. In total, 21 QTLs were detected, among which eleven were localized to the same positions as those described previously, and ten novel QTLs were detected. Six QTLs were detected in both trials. The results of 10 QTLs identified for fruit size related traits suggested that fruit size was mainly determined by fruit diameter and flesh thickness of which major QTLs were mapped on LG5 and LG11. One QTL for ECOL possessing a high allelic effect, qECOL4 was closely linked with marker CMBR154, suggesting the potential application in marker-assisted breeding. Two QTLs controlling flesh color were positioned in LG5 and LG8, respectively. The fruit netting, a crucial appearance factor in Asian market is an important study focus, in particular netting width. Four QTLs were defined for both netting density and netting width. This is the first report on QTL mapping for netting width.
Powdery mildew (Podosphaera xanthii) is a serious disease of melon. Ten melon differentials were used to identify the races in Tainung and Taichung experimental field. Discrepancies in the respones of these differentials revealed that the predominant races existed in the open field were P. xanthii race 1 and race 5 in the two regions, but there were also a few unknown races. The evaluation results on the resistance of fifty-seven melon inbred lines to P. xanthii race 1 and race 5, showed that twenty-four inbred lines were resistant to race 1, while only two inbred lines were resistant to race 5. According to the genetic analysis of the resistant inbred line TARI-08874, the resistance was controlled by a dominant gene. The combined F2 population was also used to map the quantitative trait locus (QTL) for powdery mildew resistance. One major QTL for powdery mildew resistance was detected on LG2 which was closely linked to a simple sequence repeat (SSR) marker CMBR120 identified in a previous study.

並列關鍵字

Cucumis melo ； inter simple sequence repeat (ISSR) ； simple sequence repeat (SSR) ； quantitative trait loci (QTLs) ； genetic correlation ； fruit size ； fruit color ； flesh color ； fruit netting ； Podosphaera xanthii ； genetic analysis ； quantitative trait locus

參考文獻

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