Ethylene supports colonization of plant roots by the mutualistic fungus Piriformospora indica

The mutualistic basidiomycete Piriformospora indica colonizes roots of mono- and dicotyledonous plants, and thereby improves plant health and yield. Given the capability of P. indica to colonize a broad range of hosts, it must be anticipated that the fungus has evolved efficient strategies to overcome plant immunity and to establish a proper environment for nutrient acquisition and reproduction. Global gene expression studies in barley identified various ethylene synthesis and signaling components that were differentially regulated in P. indica-colonized roots. Based on these findings we examined the impact of ethylene in the symbiotic association. The data presented here suggest that P. indica induces ethylene synthesis in barley and Arabidopsis roots during colonization. Moreover, impaired ethylene signaling resulted in reduced root colonization, Arabidopsis mutants exhibiting constitutive ethylene signaling, -synthesis or ethylene-related defense were hyper-susceptible to P. indica. Our data suggest that ethylene signaling is required for symbiotic root colonization by P. indica

Complete genome sequence of a new bipartite begomovirus infecting cotton in the Republic of Benin in west Africa

Here, we report the complete genome sequence of a novel bipartite begomovirus isolated from cotton plants (Gossypium raimondii, Malvaceae) exhibiting light yellow mosaic symptoms. The genome sequence was determined by Illumina DNA sequencing and confirmed by Sanger sequencing of RCA-enriched, cloned circular genomic components. The DNA-A and DNA-B components were each ~2.7 kb in size, and their genome arrangement was characteristic of other Old World bipartite begomoviruses. While the DNA-A component was most closely related to tobacco leaf curl Comoros virus (TbLCKMV) at 80 %, the DNA-B component had as its closet relative soybean chlorotic blotch virus (SbCBV) at 66 %. This previously undescribed begomovirus is herein named “cotton yellow mosaic virus” (CYMV)

Acibenzolar-S-methyl induces resistance against cassava mosaic geminiviruses in Nicotiana benthamiana and their vector Bemisia tabaci in cassava (Manihot esculenta)

Published online: 21 Aug 2021Cassava mosaic disease (CMD), caused by cassava mosaic geminiviruses (CMGs), is a major constraint to the cassava crop in Africa and southeastern Asia. Here, we investigated the ability of acibenzolar-S-methyl (ASM), a functional analog of salicylic acid (SA), to trigger systemic acquired resistance (SAR) against two CMGs, namely African cassava mosaic virus (ACMV) and East African cassava mosaic Cameroon virus (EACMCV) in Nicotiana benthamiana. ASM treatment delayed the time to first viral symptoms appearance, reduced virus infection rate, and attenuated symptoms. Furthermore, ASM caused an enhanced recovery from symptoms of both viruses and inhibited plant death observed in N. benthamiana plants infected by EACMCV. This study further showed that ASM induced resistance to the whitefly Bemisia tabaci (Gennadius), the vector of CMGs, in cassava. Notably, we observed that ASM treatment affected adult whitefly feeding preference and oviposition in cassava under both choice and no-choice conditions. A significant reduction in whitefly adult, egg, and nymph populations was observed irrespective of ASM treatment. The results of this study show that ASM has the potential to control both CMGs and their whitefly vector which is an important first step toward managing whitefly and cassava viruses