Mengistu Alemu, Castlebury Lisa, Smith Rusty, Ray Jeff, Bellaloui Nacer
USDA, ARS, Crop Genetics and Production Research Unit, Jackson, TN 38301.
USDA, ARS, Systematic Botany and Mycology Laboratory, Beltsville, MD 20705.
Plant Dis. 2009 Oct;93(10):1009-1018. doi: 10.1094/PDIS-93-10-1009.
Phomopsis longicolla is a major seed pathogen of soybean (Glycine max) in hot, humid environments. The objective of this study was to monitor the infection and development of P. longicolla on vegetative and reproductive tissues of six cultivars and to determine the relationship between this infection and subsequent seed infection and seed germination. Cultivars were grown for 3 years (2002 to 2004) without irrigation or with irrigation applied at pre- plus postflowering or at postflowering growth stages. P. longicolla was isolated most frequently from leaf, stem, pod, root, and seed. Diaporthe phaseolorum and three unidentified Phomopsis sp. were also isolated. Diaporthe aspalathi, which previously has not been reported on soybean, was also recovered from leaf samples. These isolates, however, were recovered very infrequently. Recovery of P. longicolla from roots was much lower than from leaves, stems, and pods in all years and irrigation environments. The recovery of P. longicolla from seed was affected by irrigation environments. Seed from irrigated plots had more P. longicolla than that from nonirrigated plots. Isolation of P. longicolla from seed was negatively correlated with percentage of seed germination in irrigated environments but not in the nonirrigated environment. Pod infection was correlated with seed infection in all three irrigation environments. Even though infection of leaves and stems increased with increasing moisture availability, such infection did not consistently correlate with seed infection. Seed germination and seed infection were negatively correlated with percent hard seed. This study provided the first demonstration of the seasonal progression of P. longicolla on soybean cultivars grown under three irrigation environments.
菜豆荚孢是炎热潮湿环境中大豆（Glycine max）的一种主要种子病原菌。本研究的目的是监测菜豆荚孢在六个品种营养组织和生殖组织上的侵染及发育情况，并确定这种侵染与后续种子侵染和种子萌发之间的关系。这些品种种植了3年（2002年至2004年），有的不灌溉，有的在开花前和开花后或开花后生长阶段进行灌溉。菜豆荚孢最常从叶片、茎、豆荚、根和种子中分离得到。还分离出了菜豆间座壳和三种未鉴定的荚孢属真菌。从叶片样本中还分离出了此前未在大豆上报道过的Aspalathus间座壳。然而，这些分离物的分离频率非常低。在所有年份和灌溉环境中，从根中分离到菜豆荚孢的频率远低于从叶、茎和豆荚中分离到的频率。从种子中分离菜豆荚孢受灌溉环境的影响。灌溉地块的种子比未灌溉地块的种子带有更多的菜豆荚孢。在灌溉环境中，从种子中分离菜豆荚孢与种子发芽率呈负相关，但在非灌溉环境中并非如此。在所有三种灌溉环境中，豆荚侵染与种子侵染相关。尽管叶片和茎的侵染随着水分供应的增加而增加，但这种侵染与种子侵染并不总是相关。种子发芽和种子侵染与硬实种子百分比呈负相关。本研究首次展示了菜豆荚孢在三种灌溉环境下种植的大豆品种上的季节性发展情况。
