What question did this study set out to answer?

To identify and map the major recessive allele controlling metribuzin tolerance in tomato.

February 14, 2026

Genetic mapping of a major-effect recessive allele controlling high levels of metribuzin tolerance on tomato chromosome 1

MGMatías González-ArcosInstituto Nacional de Investigación Agropecuaria MFMaría Esther N. Fonseca DGDário GrattapagliaBrazilian Agricultural Research Corporation

Key Points

To identify and map the major recessive allele controlling metribuzin tolerance in tomato.
Conducted inheritance studies using the cross between metribuzin-sensitive and tolerant cultivars.
Performed bulked segregant analysis to identify PCR markers linked to the tolerance allele.
Utilized genome-wide linkage mapping with solCAP SNP markers on chromosome 1.
Identified the mtz allele as the major contributor to metribuzin tolerance in tomato.
Established two closest SNP markers flanking the mtz locus at 3.78 and 21.4 cM distance.
Achieved a 91.9% success rate in marker assisted selection for high tolerance levels.

Abstract

Metribuzin is a large-spectrum herbicide extensively employed in the tomato crop. Even at recommended doses and suitable application times, many cultivars might display varying degrees of metribuzin toxicity. Hence, the deployment of cultivars with genetic tolerance could facilitate weed management. The inbred line ‘CNPH–0498’ (derived from ‘UGA-1113-MT’) displayed high levels of metribuzin tolerance. Inheritance studies were carried out using populations derived from the cross ‘Viradoro’ (a metribuzin-sensitive cultivar) × ‘CNPH–0498’. The segregation patterns strongly indicated that tolerance is under control of a major effect recessive allele, tentatively named as mtz . Bulked segregant analysis was used to identify a scorable PCR marker (OP-Z11-950) linked in repulsion phase to mtz . Cloning and sequencing allocated OP-Z11-950 amplicon on chromosome 1. Denser genome-wide linkage mapping was carried out with 1056 co-dominant solCAP SNP markers genotyped with the EMBRAPA Multispecies 65 K chip. The two closest SNP markers were positioned at 3.78 and 21.4 cM distance, flanking the tolerant locus at the long arm of chromosome 1. Multiple-round genomic scans confirmed mtz as the only locus segregating with the metribuzin tolerance in a mapping population of 501 F 2 individuals. Haplotype analysis revealed a success rate of 91.9% in marker assisted selection for high levels of tolerance. The genetic mapping of mtz is the first step to understand the physiological bases of the tolerance and to move towards the large-scale manipulation of this trait in breeding programs.

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