Host‐ and stage‐dependent secretome of the arbuscular mycorrhizal fungus Rhizophagus irregularis

Arbuscular mycorrhizal fungi form the most wide‐spread endosymbiosis with plants. There is very little host specificity in this interaction, however host preferences as well as varying symbiotic efficiencies have been observed. We hypothesize that secreted proteins (SPs) may act as fungal effectors to control symbiotic efficiency in a host‐dependent manner. Therefore, we studied whether arbuscular mycorrhizal (AM) fungi adjust their secretome in a host‐ and stage‐dependent manner to contribute to their extremely wide host range. We investigated the expression of SP‐encoding genes of Rhizophagus irregularis in three evolutionary distantly related plant species, Medicago truncatula, Nicotiana benthamiana and Allium schoenoprasum. In addition we used laser microdissection in combination with RNA‐seq to study SP expression at different stages of the interaction in Medicago. Our data indicate that most expressed SPs show roughly equal expression levels in the interaction with all three host plants. In addition, a subset shows significant differential expression depending on the host plant. Furthermore, SP expression is controlled locally in the hyphal network in response to host‐dependent cues. Overall, this study presents a comprehensive analysis of the R. irregularis secretome, which now offers a solid basis to direct functional studies on the role of fungal SPs in AM symbiosis.     

贵州烟草根围AM真菌多样性的初步研究

从贵州省内烟区不同土壤生态环境下采集烟草根际土样,湿筛离心法分离丛枝菌根（AM）真菌孢子,鉴定出烟草AM真菌4属20种,其中球囊霉属9种,无梗囊霉属7种,巨孢囊霉属3种,盾巨孢囊霉属1种。从土壤样品DNA中扩增AM真菌特异性片段并采用DGGE技术对AM真菌多样性进行分析。测序结果显示烟草根际土壤中菌根真菌主要菌群为球囊霉属,与湿筛离心法的鉴定结果一致。为进一步研究贵州地区AM真菌多样性以及开发应用提供了依据。