Ocimati Walter, Were Evans, Groot Jeroen C J, Tittonell Pablo, Nakato Gloria Valentine, Blomme Guy
Farming Systems Ecology Group, Plant Sciences, Wageningen University & Research, Wageningen, Netherlands.
Bioversity International, Kampala, Uganda.
Front Plant Sci. 2018 Oct 10;9:1471. doi: 10.3389/fpls.2018.01471. eCollection 2018.
Alternative host plants are important in the survival and perpetuation of several crop pathogens and have been suspected to play a role in the survival of pv. (Xcm) and perpetuation of Xanthomonas wilt (XW) disease of banana and enset. This study determined the potential risk posed by two weeds ( spp. and wild sorghum) and common banana intercrops (maize, millet, sorghum, taro, and sugarcane) as alternative hosts to Xcm. The study employed screenhouse experiments, laboratory procedures and diagnosis of banana fields in XW-affected landscapes. Typical XW symptoms were only observed in artificially inoculated sp., with an incidence of 96%. Leaf lesions characteristic of xanthomonads occurred on millet (50%) and sorghum (35%), though the plants recovered. No symptoms occurred in maize, sugarcane, taro or wild sorghum. However, Xcm was recovered from all these plant species, with higher recoveries in sp. (47%), millet (27%), sugarcane (27%), and wild sorghum (25%). Only isolates recovered from sp., millet, sorghum and wild sorghum caused disease in banana plantlets. The presence and incidence of XW on-farm was positively associated with the presence of susceptible ABB genotypes and negatively with number of banana cultivars on farm and household access to training on XW management. Only 0.02% of field sampled spp. plants had Xcm. Risk posed by spp. on-farm could be limited to tool transmission as it has persistent floral bracts that prevent insect-mediated infections. Given the high susceptibility, perennial nature and propagation through rhizomes of sp., it could pose a moderate-high risk, thus warranting some attention in the management of XW disease. Sugarcane could offer a low-moderate risk due to its perennial nature and propagation through rhizomes while risk from maize, millet, and sorghum was deemed zero-low due to their annual nature, wind-mediated mode of pollination and propagation through seed. Understanding the interactions of a crop pathogen with other plants is thus important when diversifying agroecosystems. The study findings also suggest other factors such as cultivar composition and management of the disease at farm and landscape level to be important in the perpetuation of XW disease.
替代寄主植物对多种作物病原体的存活和延续至关重要，并且一直被怀疑在香蕉细菌性枯萎病菌（Xcm）的存活以及香蕉和埃塞俄比亚蕉的细菌性枯萎病（XW）的延续中发挥作用。本研究确定了两种杂草（[杂草名称1]和野生高粱）以及常见的香蕉间作作物（玉米、小米、高粱、芋头和甘蔗）作为Xcm替代寄主所带来的潜在风险。该研究采用了温室试验、实验室方法以及对受XW影响地区的香蕉田进行诊断。典型的XW症状仅在人工接种的[植物名称1]中观察到，发病率为96%。小米（50%）和高粱（35%）上出现了黄单胞菌属特有的叶斑，不过这些植株恢复了。玉米、甘蔗、芋头或野生高粱上未出现症状。然而，从所有这些植物物种中都分离出了Xcm，在[植物名称1]（47%）、小米（27%）、甘蔗（27%）和野生高粱（25%）中的分离率更高。仅从[植物名称1]、小米、高粱和野生高粱中分离出的菌株能使香蕉幼苗染病。农场中XW的存在和发病率与易感的ABB基因型的存在呈正相关，与农场中香蕉品种的数量以及农户获得的XW管理培训呈负相关。田间采样的[杂草名称1]植株中只有0.02%感染了Xcm。[杂草名称1]在农场造成的风险可能仅限于工具传播，因为它有持久的苞片，可防止昆虫介导的感染。鉴于[植物名称1]的高易感性、多年生特性以及通过根茎繁殖，它可能构成中高风险，因此在XW病的管理中值得关注。由于甘蔗的多年生特性以及通过根茎繁殖，它可能带来低中风险，而玉米、小米和高粱由于其一年生特性、风媒授粉方式以及通过种子繁殖，其风险被认为是零低风险。因此，在使农业生态系统多样化时，了解作物病原体与其他植物的相互作用非常重要。研究结果还表明，其他因素，如品种组成以及农场和景观层面的病害管理，对XW病的延续也很重要。
