Molecular validation of Tomato Yellow Leaf curl Virus (TYLCV) (Ty-1/3, Ty-2 and Ty-3), Fusarium wilt (I-2) and Root- Knot Nematode (Mi-1) resistance in the breeding lines of tomato (Solanum lycopersicum L.)

Gene based molecular screening for disease resistance has become a prominent and widely adopted approach in contemporary tomato breeding programs, both in the public and private sectors. The effectiveness of disease-resistant molecular screening relies on the selection of suitable markers that span the entire genomic region for accurate identification of resistant alleles. In this study, various co-dominant and dominant Sequence Characterized Amplified Region (SCAR) markers were employed to screen for resistance genes associated with Tomato yellow leaf curl virus (TyLCV) Ty -1, Ty -2, Ty -3, Fusarium wilt (race-2) I-2, and Root-knot Nematode (( Meloidogyne incognita ) Mi -1. The selected markers exhibited high robustness in distinguishing between resistant and susceptible lines. Co-dominant SCAR markers M2 ( Ty -1 gene) and TG0302 ( Ty-2 gene) efficiently identify homozygous or heterozygous alleles in Tomato yellow leaf curl virus (TyLCV) screening. The P6-25 marker for Ty -3 gene discerns Ty -3, Ty -3a, and Ty -3b alleles, enhancing allele specificity. In Fusarium wilt I -2 gene screening, I-2/5 ensures accurate identification, while in Root-knot Nematode Mi -1 gene screening, co-dominant marker Mi-23 reliably identify and distinguishes homozygous or heterozygous resistant lines without false positives for I -2 and Mi -1 genes. This streamlined marker assisted approach optimizes disease resistance screening in tomato breeding, providing valuable insights for disease resistant cultivar development.