St. Augustinegrass [Stenotaphrum secundatum (Walter) Kuntze] is a popular warm-season turfgrass in the southern United States. Gray leaf spot (GLS), caused by the fungal pathogen Pyricularia oryzae Cavara, is one of the major diseases in St. Augustinegrass. Although previous studies have reported polyploid lines with resistance to GLS, no comprehensive evaluations of sources of resistance have been performed in the genus. Such evaluations will enable breeders to identify resistant parents for cultivar development. In this study, 58 genotypes of St. Augustinegrass and two genotypes of pembagrass [Stenotaphrum dimidiatum (L.) Brongn.] were screened for resistance to three different P. oryzae sources of inoculum under controlled environmental conditions. The parameters evaluated were incubation period, number of leaves with lesions, mean lesion length, area under the disease progress curve (AUDPC), and area under the lesion expansion curve (AULEC). Significant differences among genotypes were identified. Polyploid genotypes PI 365031, PI 290888, PI 300129, PI 300130, and cultivar ‘FX-10’ and diploid genotype PI 410353 consistently showed high levels of resistance across trials, inoculum sources, and parameters. The identification of resistance genes in diploid genotypes is of great importance for future St. Augustinegrass breeding efforts, as this germplasm pool can be more readily exploited because of the lack of reproductive barriers with most commercial cultivars and plant introductions.

中文翻译：

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黄花菜种质中灰斑病抗性来源的鉴定

圣奥古斯丁草[ Stenotaphrum secundatum (Walter) Kuntze] 是美国南部流行的暖季草坪草。灰叶斑病 (GLS) 是由真菌病原体Pyricularia oryzae Cavara 引起的，是圣奥古斯丁草的主要病害之一。尽管之前的研究报告了对 GLS 具有抗性的多倍体系，但尚未对该属进行全面的抗性来源评估。此类评估将使育种者能够识别用于栽培品种开发的抗性亲本。在这项研究中，筛选了58 个基因型的圣奥古斯丁草和两个基因型的长尾草[ Stenotaphrum dimidiatum (L.) Brongn.] 对三种不同的稻瘟病菌的抗性受控环境条件下的接种源。评估的参数是潜伏期、病斑叶数、平均病斑长度、病害进展曲线下面积 (AUDPC) 和病斑扩大曲线下面积 (AULEC)。确定了基因型之间的显着差异。多倍体基因型 PI 365031、PI 290888、PI 300129、PI 300130 以及栽培品种“FX-10”和二倍体基因型 PI 410353 在整个试验、接种源和参数中始终表现出高水平的抗性。二倍体基因型中抗性基因的鉴定对于未来的圣奥古斯丁草育种工作非常重要，因为由于大多数商业栽培品种和植物引进缺乏生殖障碍，因此可以更容易地利用该种质库。