Plant Breeding, Genetics and Biotechnology Division, International Rice Research Institute (IRRI), Los Baños, Philippines.
PLoS One. 2013 Jun 11;8(6):e66180. doi: 10.1371/journal.pone.0066180. Print 2013.
Rice blast, caused by Magnaporthe oryzae, causes yield losses associated with injuries on leaves and necks, the latter being in general far more important than the former. Many questions remain on the relationships between leaf and neck blast, including questions related to the population biology of the pathogen. Our objective was to test the hypothesis of adaptation of M. oryzae isolates to the type of organ they infect. To that aim, the components of aggressiveness of isolates originating from leaves and necks were measured. Infection efficiency, latent period, sporulation intensity, and lesion size were measured on both leaves and necks. Univariate and multivariate analyses indicated that isolates originating from leaves were less aggressive than isolates originating from necks, when aggressiveness components were measured on leaves as well as on necks, indicating that there is no specialization within the pathogen population with respect to the type of organ infected. This result suggests that the more aggressive isolates involved in epidemics on leaves during the vegetative stage of the crop cycle have a higher probability to infect necks, and that a population shift may occur during disease transmission from leaves to necks. Implications for disease management are discussed.
稻瘟病由稻瘟病菌引起，会导致叶片和稻颈受伤，从而造成产量损失，其中稻颈受伤比叶片受伤更为严重。目前，人们对稻颈瘟和叶瘟之间的关系仍存在诸多疑问，包括与病原菌种群生物学相关的问题。本研究旨在验证稻瘟病菌分离株对其感染器官类型适应性的假说。为此，我们测定了来自叶片和稻颈的分离株的致病性组分。在叶片和稻颈上测定了侵染效率、潜伏期、产孢强度和病斑大小。单变量和多变量分析表明，与来自稻颈的分离株相比，来自叶片的分离株的致病性较弱，这表明在感染器官类型方面，病原菌种群中没有特化现象。这一结果表明，在作物生长周期的营养生长阶段，叶片上的病害流行中涉及的更具侵袭性的分离株更有可能感染稻颈，并且在从叶片到稻颈的病害传播过程中，可能会发生种群转移。文中还讨论了这一结果对病害管理的意义。
