台灣芻料燕麥品系之性狀評估及探索式關聯分析

Abstract

燕麥（Avena sativa L.）為禾本科早熟禾亞科燕麥屬植物，主要供應人類食用，亦為優良的芻料作物；是臺灣草食動物業者偏好之進口乾草選項。為評估臺灣生產芻料燕麥之潛力，本研究透過Quaker International Oat Nursery（QION）引入來自美國及加拿大等8個遍布南北美洲育種單位提供之178個燕麥種原，並於2016年秋季至2017年春季於臺北及恆春兩地分別調查其在臺灣之生長情形及農藝性狀表現。試驗結果顯示，在臺北種植之燕麥開花期平均110天、株高平均100.8公分、每小區（一米單行區）乾草產量平均為367.4公克。於恆春種植之燕麥開花期平均117天、株高平均56.0公分、每小區乾草產量平均558.7公克。我們根據開花日數將試驗品系區分為早、中、晚熟品種，之後根據產量進行選拔：各成熟群表現最佳的個體在臺北或恆春各有不同，但有八個品系於兩地均有良好的產量表現。此外，我們利用覆蓋全基因體之1,164單一核苷酸多型性分子標誌（single nucleotide polymorphisms, SNPs）探討樣本之族群結構及芻料相關性狀的遺傳組成。主成分分析顯示本實驗所使用的品系沒有明顯的分群。全基因體關聯性分析（genome-wide association study，GWAS）顯示位於燕麥共識圖譜（consensus map）Mrg20連鎖群上的GMI_ES_LB_8077與尚未定位的GMI_GBS_18071和開花日數顯著相關（p-value <0.001）。其他與開花期、株高、生物量可能有關的位點分布於Mrg01、02、04、09、20，大多符合前人研究，亦在Mrg13、17、18發現文獻中尚未報導的候選位點。本研究結果可作為選育適合臺灣的芻料燕麥之參考，並有助未來相關性狀遺傳解析。

Oat (Avena sativa L.), which belongs to family Poaceae, subfamily Pooideae, and genus Avena, is mainly used for human consumption. It is also an excellent forage crop, and a preferred hay option often imported by Taiwanese rumen animal husbandry. To evaluate the potential of forage oat production in Taiwan, we introduced through Quaker International Oat Nursery (QION) 178 oat breeding lines from eight breeding programs across North and South America. These breeding lines were evaluated in Taipei and Hengchun, respectively, from fall 2016 to spring 2017. Result showed that the average days-to-flowering of oats in Taipei was 110 days, with 100.8 cm average plant height, and an average dry mass yield of 367.4 g per one-meter single-row plot. The average days-to-flowering of oats in Hengchun was 117 days, with average plant height of 56.0 cm, and the average dry matter yield of 558.7 g per plot. According to days of flowering, entries were divided into early, medium and late groups, and selection was carried out according to the biomass yield performance. Individuals with the best performance in each maturity group in Taipei and in Hengchun were different, but eight entries showed good yield performance at both locations. In addition, we assessed the population structure of our sample by principal component analysis on 1,164 single nucleotide polymorphisms (SNPs) covering the whole genome to explore the genetic structure of the sample population structure and related traits. The results showed no obvious sub-population within the sample. Genome-wide association study indicated two SNP markers, GMI_ES_LB_8077 located on Mrg20 of the oat consensus map and GMI_GBS_18071 at unknown position were significantly associated with days to flowering (p-value <0.001). Several other candidate SNPs that may be associated with flowering, plant height, and yield were co-localised with candidate regions on Mrg01, 02, 04, 09, 20, and were consistent with previous studies. New potential associations on Mrg13, 17, and 18 were observed in our study. The superior entries from our study can be used as new forage varieties or breeding lines in Taiwan and and information provided by this study can help in further genetic analysis.