Identification of phytoplasma in six fruit crops in India

Abstract

Symptoms of decline, leaf yellowing and reddening, little leaf and malformation were observed in apricot, guava, lychee, mango, pomegranate and grapevine in fruit orchards belonging to three states of India namely Delhi, Maharashtra and Jammu & Kashmir during 2016–2017. Phytoplasmas belonging to three different groups were detected in all the symptomatic fruit tree samples in polymerase chain reaction with phytoplasma specific primer pairs amplifying 16S rRNA and secA genes. Pair wise sequence comparison and phylogenetic analysis confirmed the presence of phytoplasmas. A ‘Candidatus Phytoplasma asteris’ - related strain was detected in apricot showing decline symptoms in Siot (Jammu & Kashmir). ‘Ca. P. australasia’ - related strain was identified in guava, lychee, mango and pomegranate in Rajbag, Sunjwan (Jammu & Kashmir), Pusa (Delhi) and Baramati (Maharashtra), respectively, exhibiting little leaf, leaf yellows and malformation symptoms. Furthermore, a rice yellow dwarf group (16SrXI-B) - related strain was detected in pomegranate and grapevine that showed leaf yellowing and reddening at Pusa (Delhi) and Baramati (Maharashtra), respectively. Subgroup analysis using virtual RFLP of 16S rDNA sequences allowed enclosing these phytoplasma strains into 16SrI-B, 16SrII-D and 16SrXI-B subgroups. In the study, identification of phytoplasma subgroups, 16SrI-B in apricot, 16SrII-D in guava, lychee, mango and pomegranate (Pusa) and 16SrXI-B in pomegranate (Baramati) and grapevine, are the first records globally.