Evaluation of eggplant genotypes and coat protein cistron based characterization of cucumber mosaic virus eggplant isolates of subgroup IB from Pothwar region of Pakistan

Abstract

Cucumber mosaic virus (CMV) is a destructive and menace to a wide range of plant species including eggplant crop worldwide. This study was carried out to define the current status of CMV infecting eggplant crop in Pothwar region of Pakistan and characterization of CMV eggplant isolates as well as to recognize the sources of resistance in eggplant genotypes. A total of 660 leaf samples with the virus and virus-like symptoms were collected from different sites of Pothwar region and subjected to CMV specific DAS-ELISA using monoclonal antibodies. ELISA results indicated that approximately 56% of samples were positive for CMV infection and the disease incidence was highest (62.50%) in Jhelum district followed by Rawalpindi (58.33%), Chakwal (58.33%) and Attock (55.55%) districts with the lowest disease incidence (46.15%) was recorded in Islamabad district. Two ELISA positive samples from each district were further confirmed by RT-PCR and subsequently sequenced based on their coat protein cistron. All isolates were identical to each other so the nucleotide sequence of one eggplant isolate (CMV-Pak) was deposited in GenBank with accession number MH119063. BLAST and phylogenetic analysis revealed that CMV-Pak eggplant isolate shared 90-94% nucleotide and 80-100% amino acid similarities with other isolates available in GenBank. Moreover, 10 eggplant genotypes were tested against CMV-Pak eggplant isolate, ELISA results categorized three genotypes (Singh Nath 666, Neelum, and Brinjal Jamak) as moderately resistant, two genotypes (Round Black, and Global Brinjal PPL) as susceptible and rest of the five genotypes (Bemissal, Brinjal Shilpa, Short Purple, Brinjal PPL, and Namyal Ratchburi) as moderately susceptible. Therefore, the three moderately resistant genotypes could be recommended to farmers for farming and plant breeders for developing new eggplant resistant genotypes to CMV. To the best of our knowledge, this study is the first time provided evidence that CMV infects eggplant in Pakistan.