P-600 - Screening of Texas Plumeria Germplasm Collection Reveals Chronic Infection by Two Distinct Tobamovirus Species

Tuesday, August 5, 2025

10:15 AM - 11:00 AM HST

Location: Exhibit Hall 3

Presenting Author(s)

OA

Olufemi J. Alabi, PhD

Professor & Extension Specialist
Texas A&M University System
Weslaco, TX, USA

Author(s)

CV

Cecilia Villegas

Texas A&M AgriLife Research and Extension Center
Weslaco, Texas, United States
JO

John J. Oladokun

Texas A&M AgriLife Research and Extension Center
Weslaco, Texas, United States
AB

Ana Kelle Brito De Deus

Earth University
Gúacimo, Limon, Costa Rica
TT

Tongyan Tian

California Department of Food and Agriculture
Sacramento, California, United States
KO

Kevin Ong, PhD

Director of The Texas Plant Disease Diagnostic Laboratory & Professor in the Department of Plant Pat
Texas A&M University System
College Station, Texas, United States
MA

Maher Al Rwahnih, PhD

Foundation Plant Services
Davis, California, United States

Abstract Text: Concerned about the potential spread of frangipani mosaic virus (FrMV) during exchange of plumeria cuttings, a collection of plumeria cultivars held by hobbyists and traders in Texas were sampled for virus testing from 2023 to 2024. Total RNA extracts were made from 104 whole leaf or stem cuttings, followed by cDNA synthesis and PCR screening with two newly designed diagnostic primers targeting the coat protein and replicase gene segments of tobamoviruses FrMV and plumeria mosaic virus (PluMV), respectively. The results revealed the occurrence of both viruses in mixed infections in 39.4% of the samples, FrMV alone in 39.4%, and PluMV alone in 10.6%; The remaining 11 samples tested negative for both viruses. Both viruses were mechanically transmissible onto Nicotiana benthamiana plants, inducing systemic symptoms of mosaic/mottling, foliar necrosis and growth retardation. Transmission electron microscopy revealed the presence of stiff rod virions of variable lengths in both the natural and experimental host plants further confirming Tobamovirus infection. The results showed that FrMV and PluMV are highly prevalent in Texas Plumeria Germplasm collection likely due to their inadvertent spread via symptomless vegetative cuttings. In this regard, the primers designed in this study would facilitate routine diagnosis of plumeria germplasm to limit accidental spread of viruses. Further studies are needed to determine the genetic diversity of FrMV and PluMV isolates in Texas, and to exclude the possible occurrence of novel viruses from the plumeria germplasm collection.