Diagnosis of a new variant of soybean yellow mottle mosaic virus with extended host-range in India

Abstract

Soybean yellow mottle mosaic virus (SYMMV, genus Carmovirus) was previously known to occur in South Korea and USA causing bright yellow mosaic in soybean. In this study, SYMMV (Car-Mb14 isolate) was isolated from mungbean (Vigna radiata) exhibiting mild mottling and puckering symptoms in the experimental field at Indian Agricultural Research Institute, New Delhi during 2012. The virus isolate, Car-Mb14 induced veinal mottling, mild mottling, chlorotic blotching, local and systemic necrosis in soybean, mungbean, blackgram, French bean and guar bean, respectively. The symptomatology of the present isolate of SYMMV was different from the previously reported South Korean isolate, as the later did not induce symptoms in any of the above legumes other than soybean. The present isolate was phylogenetically distinct and shared 90-93 % sequence identity in coat protein (CP) of 52 SYMMV isolates reported from Korea and USA. In order to know the serological relationships, the CP gene of the present isolate was over expressed as a 39 kDa protein in E. coli and an antiserum of 1:16,000 titer against the recombinant CP was produced. Serological cross reactivity analysis revealed that SYMMV was serologically related to blackgram mottle virus but not to cowpea mottle virus, the other legume infecting carmoviruses. The antiserum was used to detect prevalence of SYMMV in legume crops by ELISA. Out of 145 field samples of legumes (mungbean, blackgram, French bean and soybean) collected from different places in India, SYMMV was detected only in 16 samples of mungbean and one sample of blackgram. The natural infection of SYMMV in mungbean and blackgram was further confirmed based on CP gene sequence. This study provides evidence of occurrence of a new variant of SYMMV with distinct symptom phenotype and extended host-range in India.

Response of morphological, anatomical, and agronomic characteristics of soybean genotypes to Cowpea Mild Mottle Virus

“…The decrease in the total number of pods in susceptible genotypes was thought to be due to a decrease in metabolic processes in susceptible soybean plants due to the CpMMV attack (Nurrohman et al 2019). In many diseases, the ring spot symptom, but not caused by a virus, tends to be invisible after the initial attack and reappears under certain environmental conditions (Sandra et al 2015).…”

Molecular and biological characterization of soybean yellow mottle mosaic virus severe strain infecting soybean in India

“…Pusa Parvati by mechanical sap inoculation after homogenizing the infected soybean leaf samples in 0.1 M phosphate buffer. Systemic infected French bean leaves were used for virus purification and purified virus was subjected to immunosorbent electron microscopy (ISEM) to observe the isometric virus particles as described previously (Sandra et al 2015).…”

“…Soybean yellow mottle mosaic virus (Genus: Gammacarmovirus; Subfamily: Procedovirinae; Family Tombusviridae) (Lefkowitz et al 2018), causing symptoms of bright yellow mosaic, mottling and puckering in mungbean (Vigna radiata), soybean and urdbean (Vigna mungo) has been recently reported from India (Sandra et al 2015(Sandra et al , 2018. SYMMV mungbean isolate (SYMMV-Mb) has a single standard positive sense genomic RNA of 3974 nucleotides and do not possess 5′ cap structure and 3′ poly (A) tail.…”

“…The viral genome consists of six ORFs; ORF1 and ORF2 represents replicase associated proteins; ORF3 and ORF4 associated with viral movement, ORF5 encodes coat protein (CP) and ORF6 is of unknown function (Sandra et al 2017). Biological studies of SYMMV-Mb through mechanical sap inoculations showed that SYMMV-Mb restricts to Luguminosae members with the production of mild mottling, chlorotic blotches and veinal necrosis symptoms in various host species (Sandra et al 2015). SYMMV-Mb was a seed transmitted virus in French bean and mungbean accumulating to higher levels in the favorable temperature zone of 26-29 °C (Sandra et al 2020a, b).…”