Parthenium hysterophorus: A potential weed reservoir of tomato phytoplasmas in Andhra Pradesh, India

In July-October 2024, phytoplasma suspected symptoms of phyllody were observed in Parthenium hysterophorus weed growing in and around tomato fields showing big bud symptoms at Tirupati and Annamayya districts of Andhra Pradesh. Total DNA from symptomatic P. hysterophorus leaves was extracted using CTAB method. The P1/Tint and R16F2n/R16R2 universal primers were used and all the symptomatic tomato and weed leaf samples yielded amplifications of about 1.2 kb in nested PCR assays. Pair wise sequence identity, phylogeny and virtual RFLP analysis of 16S rRNA gene of the parthenium phytoplasma strains confirmed the presence of a Ca. P. australasiae=australasiaticum’ strain in both the tested plants. Since the P. hysterophorus weed resulted infected with a strain closely related to those of the phytoplasmas identified in tomato showing big bud symptoms, it may play a crucial role as natural reservoir of these phytoplasmas. Group 16SrII phytoplasmas are spreading widely at several geographical locations in India in diverse crops and weed species, hence improved knowledge about their strain identity, epidemiology and control are essential to reduce their further spread into new locations.