Controle genético da resistência à mosca-minadora (Liriomyza sativae) na linhagem de meloeiro EATMEL 20230013

Abstract

The melon (Cucumis melo L.) is a crop of high socioeconomic importance worldwide and in Brazil, particularly in the Northeast region. However, this vegetable crop is affected by the leafminer (Liriomyza spp.), a key pest that forms mines in the leaf tissue, reduces the photosynthetic area, and compromises yield performance. In this context, the use of resistant cultivars stands out as a sustainable strategy, making it essential to clarify the genetic inheritance of this trait. Thus, the present study aimed to elucidate the genetic control of resistance to the leafminer (Liriomyza sativae) in the melon line EATMEL 20230013.The experiment was conducted at Embrapa Agroindústria Tropical under laboratory and field conditions. From the cross between P1 and P2, the F1 generation was obtained, from which the F2 generation was derived by self-fertilization, along with backcrosses RC1 and RC2, performed with the resistant and susceptible parents, respectively. Resistance to the leafminer under artificial and natural infestation conditions was evaluated in plants from each family of the population. In the laboratory, resistance was assessed based on larval viability using an ordinal scale to classify antibiosis resistance, additionally, the mines-per-plant ratio and pupal viability were calculated, the latter only for susceptible plants. In the field, resistance was estimated using a scoring scale based on the percentage of leaves with mines. Based on the data obtained, the proportion of resistant and susceptible plants was calculated for the population families that showed phenotypic segregation, F2 and RC2, in both laboratory and field settings. Based on the observed segregation patterns, an expected genetic model for the resistance gene segregation was proposed. The observed proportions of resistant and susceptible plants across generations were compared to the expected proportions using the Chi-square test at a 5% significance level. The results demonstrated that all plants from the resistant parent P1, the F1 generation and the RC1 backcross exhibited resistance, characterized by zero larval viability and a lower mines-per-plant ratio, while the susceptible parent P2 showed 100% susceptible plants. In the F2 generation and the RC2 backcross, phenotypic segregation was observed to be compatible with 3:1 and 1:1 ratios, respectively, under both laboratory and field conditions, with no statistical difference between the observed and expected models. These results indicate that a model of complete dominance of a single gene explains the genetic control of antibiosis-type resistance to L. sativae in the melon line EATMEL 20230013 with two alleles, which conditions the expression of resistance in the offspring.