Molecular characterization, vector identification and sources of phytoplasmas associated with brinjal little leaf disease in India

Abstract

Brinjal little leaf (BLL) is a widespread disease of phytoplasma etiology in India that induces severe economic losses. Surveys were conducted in eight brinjal-growing states of India during July 2014 to September 2015 and eighteen BLL samples showing little leaf, phyllody and witches' broom symptoms were collected for phytoplasma identification. Presence of phytoplasmas was confirmed in all the eighteen BLL samples using polymerase chain reaction with phytoplasma-specific primer pairs (P1/P6, R16F2n/R16R2). Pair wise sequence comparison and phylogenetic relationship of 16S rRNA gene sequences of BLL phytoplasma strains confirmed that sixteen out of eighteen BLL strains belonged to clover proliferation phytoplasma (16SrVI) group and two BLL strains (GKP-A and GKP-B) from Gorakhpur, Uttar Pradesh, were classified under 16SrII group. Further virtual RFLP analysis of 16S rDNA sequences allowed finer classification of BLL strains into 16SrII-D and 16SrVI-D subgroups. BLL phytoplasma strains belonging to 16SrVI-D subgroup were found as the most widespread phytoplasma strains associated with BLL disease in India. 16SrVI-D subgroup phytoplasma association with two symptomatic weed species viz. Cannabis sativa subsp. sativa at Noida, Uttar Pradesh and Portulaca oleracea at IARI fields, New Delhi was also confirmed by nested PCR assays with similar set of phytoplasma-specific primers, pairwise 16S rDNA sequence comparison, phylogeny and virtual RFLP analysis. Out of five identified leafhopper species from BLL-infected fields at Noida, Uttar Pradesh and Delhi, only Hishimonas phycitis was identified as carrier and natural vector of 16SrVI-D subgroup of phytoplasmas by nested PCR assays, sequence comparison, phylogeny, virtual RFLP analysis and transmission assays.

Identification and Characterization of Phytoplasma Associated with Brinjal Little Leaf, Phyllody and Witches' Broom Disease in Four States of India

“…In the present study, association of 16SrVI-D subgroup was confirmed with BLL strains infecting brinjal plants in four states of India on the basis of sequence comparison, phylogeny and RFLP analysis of 16S rDNA sequences. Kumar et al (2017) identified the association of two major groups of phytoplasma with brinjal little leaf disease in eight states of India and also confirmed wider spread of BLL phytoplasma 16SrVI-D strains. Our results also confirmed that 16SrVI-D phytoplasma is the most widespread strain infecting brinjal crops in India.…”

“…BLL is a very serious disease causing severe losses to brinjal crops and is widespread in brinjalgrowing regions of India. Phytoplasma etiology of BLL disease in India has been confirmed on the basis of symptoms, electron microscopy, DAPI staining and PCR assays (Das and Mitra, 2004;Kumar et al, 2017;Rao and Kumar, 2017).…”

Molecular characterization of phytoplasma diseases of pepper in Turkey

“…Also, "Ca. P. trifolii" associated with pepper has been detected in Spain, China, Lebanon and India (Castro & Romero, 2002;Choueiri et al, 2007;Hiruki & Wang, 2004;Kumar & Rao, 2017).…”

Molecular characterization of phytoplasma associated with four important ornamental plant species in India and identification of natural potential spread sources

“…More than 34 weed species are reported to be the hosts of phytoplasmas belonging to five different groups (16SrI, 16SrII, 16SrV, 16SrVI and 16SrXIV) throughout India (Rao et al 2017). In India, C. sativa has already been reported as natural hosts of 16SrI, 16SrII, 16SrVI and 16SrXIV groups of phytoplasma (Raj et al 2008a, b;Mall 2009;Chaube et al 2015;Kumar et al 2017). However, P. hysterophorus was confirmed as natural host of 16SrI and 16SrII group phytoplasmas in India (Raj et al 2008b;Thorat et al 2016).…”