Estudo de herança, transferibilidade de primers, e análise de trilha e de QTL em populações de melancia (citrullus lanatus var. lanatus)

Abstract

Watermelon (Citrullus lanatus) is quite appreciated in the world, possibly for its sweet taste, easy consumption etc. However, the market has required genotypes with new characteristics of plant and fruit, such as the reduction in fruit size, making it possible to think of a parallel follow-up to the reduction of these fruits, the reduction of the size of seeds in these new commercial genotypes, the demand for these new genotypes is fast, which makes it difficult to obtain, by means of classical breeding methods, so the selection assisted by molecular markers can be used in line with these methods, seeking to speed up the obtainment of new genotypes. In view of the above, the objectives of the present study were to provide information on the seed length inheritance; estimate genetic parameters, correlations and direct and indirect effects of watermelon morpho-agronomic characteristics, in addition to testing the transferability of melon SSR primers to watermelon culture; and the possible identification of QTL using SSR primers suitable for the cultivation of watermelon. This information will be useful to subsidize the breeding programs of the species in the development of new genotypes. The populations were phenotyped: P1, P2, F1, F2, RC1 and RC2, seeking to study the seed length inheritance, as well as fruit descriptors were used to estimate genetic parameters, correlations and trail analysis; in addition to the phenotyping, genotyping of the P1, P2, F1, F2 populations was carried out, for the possible identification of QTL for the seed length; and the genotyping of six materials stored in the active watermelon germplasm bank, seeking to test the transferability of melon primers. The results of the inheritance study for the seed length showed that the character is controlled by a gene with two alleles exhibiting incomplete dominance, however this behavior can vary depending on the population studied, in addition the selection of superior individuals can be carried out with based on the phenotype; based on the genetic parameters it was possible to observe that, most of the characteristics had a greater genotypic contribution in the phenotypic expression, in addition the high heritabilities evidenced greater chances of success with the selection, the correlations indicated that for the improvement of the seed size they can be used , as response variables, the length or width of the seed, while trail analysis showed an improvement in the seed size based on the type of fruit stripes; of the 31 sequences of melon SSR primers tested for watermelon, it was possible to observe that 100% of the sequences amplified for watermelon indicating the possibility of using these sequences in watermelon breeding programs in diversity studies, possibly in confirming paternity etc. Of the 159 SSR watermelon primers used in the QTL study, only MCPI-12 was associated with the character, however, before the exploration of this sequence in breeding programs, it is necessary to validate this marker in other populations.