Morphological and molecular characterisation of tomato accessions for breeding for organic farming systems in Brazil

ABSTRACT Genetic variability is crucial for the choice of genitors in any plant breeding programme. Open-pollinated tomato varieties (OPV) present particular and little explored characteristics that can be used in breeding for organic production. This study aimed to characterise the morphological and molecular variability of seventeen OPVs grown under organic management, using morphological descriptors and SSR-type molecular markers. The experiment was conducted under field conditions, in a randomised complete block design, with four replications. Morphological characterisation was performed of 35 descriptors of the fruit and plants and by physical-chemical analyses of the fruit. Furthermore, the molecular variability of the OPVs was analysed using 20 SSR molecular markers. In the characterisation of fruit quality, 85.03% of the variability was composed of the chromatic descriptors b* (44.43%) and L* (7.21%), together with the width of pedicel scar (16.78%), number locules (8.59%), and fruit length (8.02%). The average similarity of genotypes obtained from the polymorphic SSR fragments was 0.59. The evaluated genotypes presented genetic variability to facilitate crosses focused on tomato breeding programmes for organic agriculture. Crosses including the yellow-orange-coloured genotypes, BGT_3 and BGT _1, could be explored for market niches such as for the gourmet type.