探勘花椰菜於高溫下影響結球與開花時間之基因

Abstract

花椰菜 (Brassica oleracea var. botrytis L.) 的花球因其富含豐富的營養元素以及抗氧化物質而受到消費者的喜愛與重視，在全球的總栽培面積以及產量逐年上升。花椰菜在結球時期對高溫相當敏感，全球暖化使花椰菜在營養生長轉換為生殖生長時期持續遭遇高溫，因而影響花椰菜花球的發育，使花椰菜的生長時序難以預測，更可能因此造成花椰菜的產量與品質受到影響。 環境溫度對於花椰菜生產的影響甚鉅，了解花椰菜在高溫下結球與開花的遺傳和環境的交互作用就顯得相當重要，是以本研究探勘在高溫下 (30℃) 影響花球之基因座。使用結球期較早的花椰菜自交系#1891以及結球期較晚的花椰菜自交系#1892雜交形成141個個體的F2族群建構連鎖圖譜，並結合結球時間與開花時間利用組合區間定位法 (CIM) 定位數量性狀基因座，結球時間只發現一個基因座，位於第7條染色體，可解釋29.65 % 的外表型變異；開花時間只有一個基因座，位於第9條染色體，外表型解釋率為22.37 %。候選基因之預測，則是將區間內的基因進行基因註解，在結球時間的基因座區間找到AHL27、ATL80、ALBA1以及ARF5等基因，而在開花時間的基因座區間則找到與花器官發育相關的SEP4。這些基因在親本間具有核苷酸序列的變異，這些變異位於高度保守性的蛋白質結構域內或是造成胺基酸較大物化性質差異，可能因此造成蛋白質產物功能的改變。後續可將這些候選基因進一步進行基因功能驗證以確認是否在高溫下影響花椰菜的結球與開花時間，進而應用於花椰菜耐熱品種之育種、產期調節，以維持高溫環境下花椰菜的穩定生產與品質，提升糧食安全。

The curd of cauliflower (Brassica oleracea var. botrytis L.) is favored and valued by consumers owing to its rich nutrients and antioxidant compounds, leading to an annual increase in global cultivation area and yield. Cauliflower is particularly sensitive to high ambient temperature while curding. Global warming makes cauliflower constantly exposed to high temperature during the transition of vegetative to reproductive phases of meristem and thus influences curd-forming. The unsuitable growing environment makes the growth stage of cauliflower unpredictable and therefore impacts its production. To reduce the impact of climate change on cauliflower production, it becomes crucial to understand the physiological mechanism behind the curding and flowering of cauliflower. To locate the quantitative trait loci (QTLs) that are involved in controlling curding and flowering time, 141 F2 individuals derived from the early-heading cauliflower ‘#1891’ and the late-heading cauliflower ‘#1892’ were developed to construct the linkage map and identify QTLs influencing curding time and flowering time by composite interval mapping (CIM). A total of one QTL for the curding time was mapped on chromosome 7, which could explain 29.65 % of phenotypic variation; a single QTL for the flowering time was mapped on chromosome 9 and could explain 22.37 % phenotypic variation. After annotating the genes among the intervals, AHL27, ATL80, ALBA1, and ARF5 within the curding time QTL interval were identified. For flowering time QTL, SEP4, which is involved in flower organ development was detected. These genes exhibit sequence polymorphisms between parents which are located within the highly conserved protein domains or encode amino acids with different physicochemical properties, potentially altering protein functionality. Further gene validation should be conducted to ensure whether these candidate genes influence curding and flowering time. This study would be facilitated in heat-tolerant cauliflower breeding and production season regulation to sustain the yield of cauliflowers grown in areas with high temperatures and further maintain food security in the future.