Vachellia nilotica: A new host of ‘Candidatus phytoplasma asteris’ and ‘Ca. p. trifolii’-related strains in India

Abstract

Vachellia nilotica, commonly known as gum Arabic tree or babool, is an important medicinal and timber tree grown throughout the arid regions of India. Disease symptoms as witches’ broom, stunting and declining were observed in Arabic trees at Rajinder Nagar, Delhi and Narayangaon, Pune during 2017–18. These symptoms were indicative of phytoplasma presence. Amplicons of about 1.25 kb were consistently amplified in nested PCR assays with DNA extracted from the leaflets of all the symptomatic babool samples using phytoplasma specific primer pairs P1/P7 followed by R16F2n/R2. Pairwise sequence comparison of the amplified products of 16S rDNA sequence of phytoplasma strains from babool witches’ broom (BaWB) from Delhi and babool stunting and declining (BaS&D) from Pune revealed 99.70% and 100% sequence identity with ‘Candidatus Phytoplasma asteris’ and Ca. P. trifolii’ related strains, respectively The presence of Ca. P. asteris’ (16SrI-B) and Ca. P. trifolii’ (16SrVI-D) in symptomatic babool samples was confirmed after phylogenetic and virtual RFLP analysis of 16S rRNA gene sequences. This is the first report of the presence of phytoplasmas in V. nilotica.