THE ROLE OF MARKER-ASSISTED SELECTION (MAS) AND GENOTYPING IN THE DEVELOPMENT OF INDETERMINATE, GREENHOUSE-ADAPTED TOMATO HYBRIDS: A REVIEW

Abstract

Protected cultivation places exceptional demands on the tomato (Solanum lycopersicum L.). Indeterminate hybrids grown under glass or plastic are expected to combine continuous, high-truss yield with durable resistance to a battery of soil-borne, foliar and viral pathogens, tolerance of the elevated temperatures and humidity typical of enclosed structures, and the fruit-quality attributes demanded by fresh markets. Assembling so many favourable alleles in a single F1 by phenotypic selection alone is slow, costly and, for several traits, unreliable, because resistance genes are often recessive, race-specific or masked by the environment. Marker-assisted selection (MAS) and modern genotyping have transformed this task by allowing breeders to track resistance and quality alleles directly at the DNA level, independent of growth stage, inoculum pressure or season. This review synthesises the current state of molecular-marker technology relevant to greenhouse tomato hybrid breeding: the transition from RFLP and SSR markers to SCAR, CAPS and, increasingly, single-nucleotide-polymorphism (SNP) systems such as KASP and targeted-sequencing panels; the well-characterised genes and diagnostic markers for the principal greenhouse diseases (TYLCV, TSWV, ToMV, Fusarium and Verticillium wilts, root-knot nematode, late blight and powdery mildew); marker-assisted backcrossing and gene pyramiding for stacking multiple resistances into elite indeterminate parents; and the emergence of genomic selection for polygenic traits such as yield, soluble-solids content and heat tolerance. The relevance of these tools to the tomato breeding programme of the Andijan Scientific-Experimental Station is considered, together with the practical constraints, and priorities for their adoption in Uzbekistan are proposed.