Pégard Marie, Gréard Camille, Grelier Marius, Gras Marie-Christine, Saint-Pierre Laure, Tharel Bernard, Barre Philippe, Julier Bernadette
INRAE, P3F, Lusignan, France.
GIE GRASS, Saint-Sauvant, France.
Plant Genome. 2025 Sep;18(3):e70085. doi: 10.1002/tpg2.70085.
Forage production, persistence, and associated ecosystem services provided by the major forage legume, alfalfa (Medicago sativa), may be affected by disease susceptibility. Resistance to anthracnose, caused by Colletotrichum trifolii, has been described as an oligogenic trait, but the precise location of resistance genes on the alfalfa genome is not known. Therefore, we phenotyped a set of 417 alfalfa accessions for anthracnose resistance as the frequency of resistant plants. With available genotyping by sequencing data for 380 accessions from this collection, we performed quantitative trait locus (QTL) detection by genome-wide association study (GWAS) and genomic prediction using a validation set of 97 accessions randomly selected. A wide range of variation for anthracnose resistance was observed, with newer varieties and breeding materials exhibiting greater resistance than old varieties and landraces. Accessions from America showed the highest resistance, although some European accessions also displayed notable resistance. Six QTLs, controlling 58% of the variation, were identified by GWAS. Two major QTLs were found on chromosome 8, within a region already identified in an alfalfa mapping population. Four other QTLs, each controlling less than 5% of the variation, were also found, including one near a major QTL on chromosome 4 in the model species M. truncatula. The predictive ability of our set of accessions was surprisingly high: 85%. These results are promising and highlight the potential of molecular markers and genomic prediction to improve anthracnose resistance in alfalfa breeding programs.
主要豆科牧草苜蓿（Medicago sativa）的饲草产量、持久性及相关生态系统服务可能会受到疾病易感性的影响。对由三叶草炭疽菌（Colletotrichum trifolii）引起的炭疽病的抗性被描述为一种寡基因性状，但苜蓿基因组上抗性基因的确切位置尚不清楚。因此，我们将一组417份苜蓿种质对炭疽病的抗性表型鉴定为抗性植株的频率。利用该种质中380份种质的测序数据进行基因分型，我们通过全基因组关联研究（GWAS）进行数量性状位点（QTL）检测，并使用随机选择的97份种质的验证集进行基因组预测。观察到炭疽病抗性存在广泛变异，新品种和育种材料比旧品种和地方品种表现出更强的抗性。来自美国的种质表现出最高的抗性，不过一些欧洲种质也表现出显著抗性。通过GWAS鉴定出6个控制58%变异的QTL。在第8号染色体上发现了两个主要QTL，位于苜蓿作图群体中已鉴定的一个区域内。还发现了其他4个QTL，每个控制的变异不到5%，其中一个位于模式物种蒺藜苜蓿（M. truncatula）第4号染色体上一个主要QTL附近。我们这组种质的预测能力出奇地高：85%。这些结果很有前景，突出了分子标记和基因组预测在苜蓿育种计划中提高炭疽病抗性的潜力。
