CAPS markers TAO1 and TG105 in the identification of I2 resistant gene in Nigerian accessions of tomato, Solanum lycopersicum L.

Abstract

Fusarium oxysporum (f.sp). lycopersici (Fol) is a soil-borne fungus that inhabits most tomato-growing regions of the world, causing vascular wilt disease. In Nigeria, the disease constitutes close to 40% loss in tomato yield annually. Cleaved Amplified Polymorphic Sequence (CAPS) markers TAO1 and TG105, developed elsewhere, were used to identify tomato accessions possessing the gene (I2) which confers resistance to Fol race 2. In this work, fifty Nigerian accessions of tomato, Solanum lycopersicum L., were screened with the two CAPS markers for resistant I2 gene. The primer pairs for TAO1 and TG105 produced amplification at 902 bp in 33 accessions and 450 bp in 38 accessions, respectively. The restriction enzymes Fok1 and Hinf1, for TAO1 and TG105 respectively, produced fragments at base pairs indicative of susceptible, homozygous and heterozygous resistant accessions to Fol. Restriction fragments from the two markers indicated that 11 accessions were homozygous resistant to Fol. Four of these accessions (Delila, Gem Pride, K-Small and Oxheart) occurred in the two molecular markers as homozygous resistant to Fol. The combined effect of the two markers enhanced precision in the identification of tomato accessions with resistance status to Fusarium vascular wilt.

Keywords: CAPS markers, Fusarium wilt, I2 gene, tomato accessions