Laboratorio de Patología Vegetal, IIAF, Universidad Michoacana de San Nicolás de Hidalgo, Morelia, Mich., Mexico.
Campo Experimental Ixtacuaco, CIRGOC, Instituto Nacional de Investigaciones Forestales, Agrícolas y Pecuarias, Tlapacoyan, Ver., Mexico.
Mol Biol Rep. 2020 Sep;47(9):6599-6609. doi: 10.1007/s11033-020-05711-0. Epub 2020 Aug 9.
Fusarium pseudocircinatum is the main causal agent of big-leaf mahogany malformation disease (BLMMD) of mahogany (Swietenia macrophylla) in Mexico. Although, BLMMD is the most important disease for this high-value timber species, there is a lack of information on the genetic variation present in geographically diverse isolates of F. pseudocircinatum. The objective of this study was to determine the genetic diversity of populations of F. pseudocircinatum causing BLMMD in the central western region of Mexico. A total of 611 big-leaf mahogany trees were inspected at eight sites in four states (Colima, Guerrero, Jalisco and Michoacán); of these, 42.7% showed malformation symptoms similar to those of BLMMD. Of 374 Fusarium isolates that were recovered, 277 were identified as F. pseudocircinatum, 56 were F. mexicanum, and 41 were Fusarium spp. An ISSR analysis of the F. pseudocircinatum isolates generated 51 bands of which 38 were polymorphic (76.8%) with a mean of 17 bands per primer. A total of 87 multilocus genotypes (MLGs) were identified. Nei's genetic diversity analysis showed that the isolates had a high genetic diversity average (0.147), with values ranging from 0.070 to 0.365 depending of the geographical location. An analysis of molecular variance revealed that the variation within the populations was low (27.36%), while the variation within MLGs was significant (72.64%), indicating genetic flow. Overall, the genetic variability of F. pseudocircinatum populations was high and the MLGs from Colima (Colima) and Gabriel Zamora (Michoacán) were placed centrally, which possibly is evidence of ancestry and indicates its dispersion routes in the central western region of Mexico.
镰刀菌伪旋孢腔菌是墨西哥桃花心木畸形病（BLMMD）的主要致病因子。尽管 BLMMD 是这种高价值木材物种最重要的疾病，但对于地理上多样化的镰刀菌伪旋孢腔菌分离株存在的遗传变异知之甚少。本研究的目的是确定引起墨西哥中西部地区 BLMMD 的镰刀菌伪旋孢腔菌种群的遗传多样性。在四个州（科利马州、格雷罗州、哈利斯科州和米却肯州）的八个地点共检查了 611 棵桃花心木大树；其中，42.7%的树木表现出与 BLMMD 相似的畸形症状。从 374 个回收的镰刀菌分离株中，有 277 个被鉴定为镰刀菌伪旋孢腔菌，56 个为镰刀菌墨西哥变种，41 个为镰刀菌属其他种。对镰刀菌伪旋孢腔菌分离株进行 ISSR 分析，产生了 51 条带，其中 38 条为多态性（76.8%），每条引物平均产生 17 条带。共鉴定出 87 个多位点基因型（MLG）。Nei 的遗传多样性分析表明，这些分离株的遗传多样性平均值很高（0.147），地理分布范围从 0.070 到 0.365。分子方差分析表明，种群内的变异较低（27.36%），而 MLG 内的变异显著（72.64%），表明存在遗传流动。总体而言，镰刀菌伪旋孢腔菌种群的遗传变异性很高，来自科利马（科利马）和加布里埃尔·萨莫拉（米却肯）的 MLG 处于中心位置，这可能表明其起源和在墨西哥中西部地区的传播途径。
