Studies of tomato spotted wilt virus in peanuts and transgenic Arabidopsis

Spotted wilt caused by tomato spotted wilt virus (TSWV) is a major problem in peanut production in the U.S. Cultural and chemical controls are used but have not eliminated the problem. Traditional breeding has produced cultivars with higher levels of TSWV resistance. However, the genetic mechanism for field resistance has not been documented and no cultivars are immune. Plant genetic engineering techniques have been recognized as a solution for producing virus resistant plants. Using homology-dependent gene silencing to produce resistance to TSWV has worked successfully in tobacco. Objectives of this research were to evaluate TSWV incidence and spread within peanut genotypes under field conditions, and to evaluate the effectiveness of TSWV nucleocapsid (N) genes for resistance to tomato spotted wilt using transgenic Arabidopsis as a model system.;Two cultivars, SunOleic 95R® and Southern Runner, and one breeding line from the University of Florida, 86x43-1-1-1-1-1-b2-B, were evaluated in replicated field plots at Marianna, FL, in 1998 and 1999. Treatments consisted of April and May planting dates with 7.6 or 15.2 cm space plantings. The presence of TSWV was determined by Enzyme-Linked Immunosorbent Assay (ELISA). SunOleic 95R® had the highest incidence of tomato spotted wilt, followed by Southern Runner and 86x43. TSWV was found in the root crown of SunOleic 95RC® earlier than for Southern Runner and 86x43. 86x43 had the highest yield, followed by Southern Runner and SunOleic 95R® May planting and 7.6 cm spacing produced the highest yields regardless of genotype.;Four types of N gene constructs were inserted into Arabidopsis through Agrobacterium-mediated transformation—(1) untranslatable sense orientation with Scaffold Attachment Regions (SARs), (2) antisense orientation with SARs, and (3) and (4) the same orientations but without SARs. Mechanical inoculation was used to evaluate TSWV resistance in transgenic Arabidopsis. The effect of SARs on transgene expression was clearly observed for both untranslatable sense and antisense orientation constructs. Transgenics containing the antisense orientation with SARs construct had the highest level of resistance to TSWV and may be the construct of choice to use in future work to develop TSWV-resistant transgenic peanut.