Shaw Michael W, Emmanuel Christy J, Emilda Deni, Terhem Razak B, Shafia Aminath, Tsamaidi Dimitra, Emblow Mark, van Kan Jan A L
School of Agriculture, Policy and Development, University of Reading, Whiteknights Reading, UK.
Laboratory of Phytopathology, Wageningen University Wageningen, Netherlands.
Front Plant Sci. 2016 May 10;7:625. doi: 10.3389/fpls.2016.00625. eCollection 2016.
Botrytis species are generally considered to be aggressive, necrotrophic plant pathogens. By contrast to this general perception, however, Botrytis species could frequently be isolated from the interior of multiple tissues in apparently healthy hosts of many species. Infection frequencies reached 50% of samples or more, but were commonly less, and cryptic infections were rare or absent in some plant species. Prevalence varied substantially from year to year and from tissue to tissue, but some host species routinely had high prevalence. The same genotype was found to occur throughout a host, representing mycelial spread. Botrytis cinerea and Botrytis pseudocinerea are the species that most commonly occur as cryptic infections, but phylogenetically distant isolates of Botrytis were also detected, one of which does not correspond to previously described species. Sporulation and visible damage occurred only when infected tissues were stressed, or became mature or senescent. There was no evidence of cryptic infection having a deleterious effect on growth of the host, and prevalence was probably greater in plants grown in high light conditions. Isolates from cryptic infections were often capable of causing disease (to varying extents) when spore suspensions were inoculated onto their own host as well as on distinct host species, arguing against co-adaptation between cryptic isolates and their hosts. These data collectively suggest that several Botrytis species, including the most notorious pathogenic species, exist frequently in cryptic form to an extent that has thus far largely been neglected, and do not need to cause disease on healthy hosts in order to complete their life-cycles.
葡萄孢属真菌通常被认为是具有侵袭性的坏死营养型植物病原体。然而，与这种普遍认知相反的是，在许多物种看似健康的宿主的多个组织内部，常常能分离出葡萄孢属真菌。感染频率达到样本的50%或更高，但通常较低，并且在一些植物物种中，隐性感染很少见或不存在。患病率因年份和组织的不同而有很大差异，但一些宿主物种的患病率通常较高。在整个宿主中发现了相同的基因型，这代表了菌丝体的传播。灰葡萄孢和拟灰葡萄孢是最常以隐性感染形式出现的物种，但也检测到了系统发育上距离较远的葡萄孢分离株，其中一种与先前描述的物种不符。只有当受感染组织受到胁迫、成熟或衰老时，才会出现孢子形成和可见损伤。没有证据表明隐性感染对宿主生长有有害影响，并且在高光条件下生长的植物中患病率可能更高。当将孢子悬浮液接种到其自身宿主以及不同宿主物种上时，来自隐性感染的分离株通常能够（在不同程度上）引发疾病，这与隐性分离株与其宿主之间的共同适应观点相悖。这些数据共同表明，包括最臭名昭著的致病物种在内的几种葡萄孢属真菌，经常以隐性形式存在，其程度迄今在很大程度上被忽视，并且它们在健康宿主上无需引发疾病即可完成其生命周期。
