Desenvolvimento marcador molecular ligado a resistência ao nematoide das galhas em alface.

Abstract

Lettuce (Lactuca sativa L.) is a vegetable that stands out for its significant economic importance among leafy vegetables. In Brazil, the occurrence of nematodes of the genus Meloidogyne has been one of the main problems for lettuce cultivation, significantly reducing its productivity. A more efficient, safe and low-cost method of controlling nematodes is the development of resistant cultivars, which can be assisted by molecular markers of the Simple Sequence Repeat (SSR) type. The objective of this work was to develop SSR molecular marker linked to resistance to root-knot nematode (M. incognita) in lettuce. To this end, a cross was carried out between the cultivar Regina 71 (female parent, susceptible to M. incognita) and the cultivar Salinas 88 (male parent, resistant to M. incognita), obtaining a plant of the F1 generation, which, when self-fertilized, resulted in 121 F2 generation plants. The DNA of all individuals was extracted, quantified and qualified. Twenty-two pre-selected SSR primers were used to amplify, via PCR (Polymerase Chain Reaction), the parental DNA and identify polymorphisms. Of these, two polymorphic primers were used to amplify the DNAs of F2 plants and evaluate the link between the molecular marks and the association between the marks and resistance. The extraction method proved to be efficient in obtaining DNA in quantity and quality for molecular analysis. The maximum likelihood analysis obtained a recombination value of 0.428 and a LOD score of 0.253807, showing that there is no connection between the molecular marks. Analysis of variance showed that there was no association between molecular marks and resistance. Even without obtaining a marker for resistance to the nematode, the research can continue with the obtaining of new molecular marks using primers evaluated in this work and which showed polymorphisms between the parents.