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POSTERS: Molecular/Cellular Plant‐Microbe Interactions I

P-353 - Growth evaluation of citrus rootstock seedlings graft-inoculated with citrus viruses and viroids

Monday, August 4, 2025
4:30 PM - 5:15 PM HST
Location: Exhibit Hall 3
Abstract Text: Virus and viroid infections are graft-transmissible. Their infections may affect growth and production of citrus trees. Commercial citrus is primarily grown on sour orange rootstock in the Lower Rio Grande Valley (LRGV) of South Texas. Citrus tristeza virus (CTV), Citrus tatter leaf virus (CTLV), Citrus exocortis viroid (CEVd), and Hop stunt viroid (HSVd) have been reported in the LRGV. Recently, CTV strains were reported in the Upper Gulf Coast. Rarely CTV-positive trees have been found in the LRGV. Citrus grown on sour orange is highly susceptible to CTV. Therefore, an evaluation of rootstocks in Texas that are tolerant to citrus viruses and viroids and perform well in highly calcareous soil is vital. Sour orange, trifoliate orange, US-942, Bitters C-22 citrandarin, C146, X639, and Alemow seedlings were grown and kept in insect resistant screenhouses. Their aboveground growth parameters were measured at three and six months after planting. C146 and X639 were the tallest plants at six months after planting. Alemow and sour orange had a larger canopy radius. The rootstocks were graft-inoculated with infected buds of CTV, CTLV, HSVd, and CEVd + HSVd. All viruses and viroids were successfully transmitted by grafting. Detection of viruses and viroids was possible in roots except for CTV in trifoliate orange and C146, and CTLV in trifoliate orange and Bitters C-22. Symptoms of leaf curl, chlorosis and distorted leaves were observed in one Bitters C-22 plant graft-inoculated with CTLV. Corky veins were observed in one sour orange plant graft-inoculated with CTV.