Phytopathology. 2014 Jan;104(1):95-107. doi: 10.1094/PHYTO-11-12-0294-R.
Since its first report in Brazil in 1985, wheat blast, caused by Magnaporthe oryzae (anamorph: Pyricularia oryzae), has become increasingly important in South America, where the disease is still spreading. We used 11 microsatellite loci to elucidate the population structure of the wheat blast pathogen in wheat fields in central-western, southeastern, and southern Brazil. No subdivision was found among the wheat-infecting populations, consistent with high levels of gene flow across a large spatial scale. Although the clonal fraction was relatively high and the two mating type idiomorphs (MAT1-1 and MAT1-2) were not at similar frequencies, the clone-corrected populations from Distrito Federal and Goiás, Minas Triangle, and São Paulo were in gametic equilibrium. Based on these findings, we propose that populations of the wheat blast pathogen exhibit a mixed reproductive system in which sexual reproduction is followed by the local dispersal of clones. Seedling virulence assays with local wheat cultivars differentiated 14 pathotypes in the current population. Detached head virulence assays differentiated eight virulence groups on the same wheat cultivars. There was no correlation between seedling and head reactions.
自 1985 年在巴西首次报告以来，由稻瘟病菌（无性型：Pyricularia oryzae）引起的小麦穗瘟在南美洲变得越来越重要，该疾病仍在蔓延。我们使用 11 个微卫星标记来阐明巴西中-西部、东南部和南部麦田中小麦穗瘟病原菌的种群结构。在感染小麦的种群中没有发现细分，这与在大空间尺度上的高水平基因流一致。尽管克隆分率相对较高，并且两个交配型异型（MAT1-1 和 MAT1-2）的频率不同，但来自 Distrito Federal 和 Goiás、米纳斯三角和圣保罗的经克隆校正的种群处于配子平衡状态。基于这些发现，我们提出小麦穗瘟病原菌种群表现出混合生殖系统，其中有性生殖后是克隆的局部扩散。对当地小麦品种的幼苗致病性测定区分了当前种群中的 14 个致病型。对同一小麦品种的离体穗部致病性测定区分了 8 个毒性群。幼苗和穗部反应之间没有相关性。
