Martins R B, Maffia L A, Mizubuti E S G
Departamento de Fitopatologia, Unviersidade Federal de Viçosa, MG, Brazil.
Phytopathology. 2008 Nov;98(11):1205-11. doi: 10.1094/PHYTO-98-11-1205.
Cercospora leaf spot is a destructive fungal disease that has become a threat to the coffee industry in Brazil. Nevertheless, little is known about populations of its causal agent, Cercospora coffeicola. We evaluated the potential of using nitrogen-nonutilizing (nit) mutants and vegetative compatibility groups (VCGs) to characterize the genetic variability of the C. coffeicola population associated with coffee plantings in Minas Gerais state (MG), Brazil. A total of 90 monosporic isolates were obtained from samples collected according to a hierarchical sampling scheme: (i) state geographical regions (Sul, Mata, and Triângulo), and (ii) production systems (conventional and organic). Nit mutants were obtained and 28 VCGs were identified. The 10 largest VCGs included 72.31% of all isolates, whereas each of the remaining 18 VCGs included 1.54% of the isolates. Isolates of the largest VCGs were found in the three regions sampled. Based on the frequencies of VCGs at each sampled level, we estimated the Shannon diversity index, as well as its richness and evenness components. Genetic variability was high at all hierarchical levels, and a high number of VCGs was found in populations of C. coffeicola associated with both conventional and organic coffee plantings.
尾孢叶斑病是一种具有破坏性的真菌病害，已对巴西的咖啡产业构成威胁。然而，对于其病原菌咖啡生尾孢菌的种群情况却知之甚少。我们评估了利用氮利用缺陷型（nit）突变体和营养体亲和群（VCG）来表征与巴西米纳斯吉拉斯州（MG）咖啡种植相关的咖啡生尾孢菌种群遗传变异性的潜力。根据分层抽样方案从采集的样本中总共获得了90个单孢分离株：（i）州地理区域（南部、马塔和三角地区），以及（ii）生产系统（传统和有机）。获得了氮利用缺陷型突变体并鉴定出28个营养体亲和群。10个最大的营养体亲和群包含了所有分离株的72.31%，而其余18个营养体亲和群每个包含1.54%的分离株。在所有采样区域都发现了最大营养体亲和群的分离株。基于每个采样水平的营养体亲和群频率，我们估计了香农多样性指数及其丰富度和均匀度成分。在所有分层水平上遗传变异性都很高，并且在与传统和有机咖啡种植相关的咖啡生尾孢菌种群中发现了大量的营养体亲和群。
