Department of Plant Pathology. University of Kentucky, Lexington 40546-0312.
Departamento de Fitopatologia, Universidade Federal de Viçosa, CEP 36570-900, Viçosa, MG Brazil.
Plant Dis. 2018 Nov;102(11):2341-2351. doi: 10.1094/PDIS-04-18-0562-RE. Epub 2018 Sep 10.
Anthracnose caused by Colletotrichum sublineola is an important disease of cultivated sorghum (Sorghum bicolor) worldwide. Anthracnose is also common on the ubiquitous wild sorghum relative Johnsongrass (S. halepense). Analysis of repetitive molecular fingerprinting markers revealed that isolates of C. sublineola from both hosts in the southeastern United States were genotypically diverse, with relatively few haplotypes found in more than one location. With few exceptions, isolates recovered from S. bicolor belonged to a population that was genetically distinct from the population recovered from S. halepense. Twenty-three isolates from cultivated sorghum were all pathogenic to at least one of 13 heritage inbred lines of S. bicolor. In all, 4 of 10 isolates from S. halepense were also pathogenic to one or more of the lines, while the rest caused no disease in greenhouse assays. The four pathogenic isolates from S. halepense were less aggressive, on average, than isolates from S. bicolor, although the ranges overlapped. Pathogenicity tests involving 15 representative pathogenic isolates from S. bicolor and S. halepense on eight heritage inbred lines of S. bicolor identified 12 races. The combined results of this study demonstrated that C. sublineola comprises two separate host-associated subpopulations in the field, even though some isolates from S. halepense were able to cause disease on S. bicolor under ideal greenhouse conditions. Nonetheless, the apparent existence of infrequent cross-infection events in the field, indicated by molecular fingerprinting, suggests that Johnsongrass has the potential to serve as a refuge and an incubator for genetic diversity in C. sublineola, which can complicate efforts to develop and deploy resistant sweet sorghum varieties in the region.
由胶孢炭疽菌引起的炭疽病是全世界栽培高粱（高粱）的重要病害。炭疽病也常见于无处不在的野生高粱近缘种 Johnsongrass（高粱 halepense）上。重复分子指纹标记分析表明，来自美国东南部两个宿主的 C. sublineola 分离株在基因型上具有多样性，在一个以上位置发现的单倍型相对较少。除了少数例外，从高粱 bicolor 中回收的分离株属于与从高粱 halepense 中回收的种群在遗传上明显不同的种群。从栽培高粱中分离出的 23 个分离株均对至少 13 个高粱 bicolor 传统近交系中的 1 种具有致病性。在所有情况下，来自 Johnsongrass 的 10 个分离株中的 4 个也对 1 个或多个系致病，而其余的在温室试验中未引起疾病。来自 Johnsongrass 的四个致病分离株平均比来自高粱 bicolor 的分离株的攻击性小，尽管范围重叠。对来自高粱 bicolor 和 Johnsongrass 的 15 个代表性致病分离株在 8 个高粱 bicolor 传统近交系上的致病性测试确定了 12 个小种。本研究的综合结果表明，即使一些来自 Johnsongrass 的分离株在理想的温室条件下能够引起高粱 bicolor 的疾病，但 C. sublineola 在田间仍由两个与宿主相关的分离种群组成。然而，分子指纹分析表明，田间偶尔发生交叉感染事件的存在表明 Johnsongrass 有可能成为 C. sublineola 遗传多样性的避难所和孵化器，这可能会使该地区开发和部署抗高粱品种的努力复杂化。
