Caracterização genética molecular de procedências e progênies de Parkia platycephala Benth

Abstract

Parkia platycephala Benth. is a tree species native to transition areas between Cerrado and Caatinga in Brazil, used for various purposes, especially for animal feed due to its high forage potential. Its intense exploitation during the fruiting season, which coincides with the forage shortage period, represents a threat to its genetic conservation in its natural habitat, requiring the study of its genetic variability. Therefore, the research aims to characterize the diversity and genetic structure existing in provenances and progenies of P. platycephala, through molecular marker ISSR (Inter Simple Sequence Repeats), as a subsidy for the genetic conservation of the species and transformation of the test of provenances and progenies in a seed orchard with environmental purposes. We sampled 45 progenies established in a test of provenance and progenies at the Experimental Farm of the Federal University of Piauí in Alvorada do Gurgueia, Piauí, Brazil. To conduct genetic analyses, we collected vegetal material from the stem and young leaf material from 180 randomly selected individuals. Estimates of primer efficiency, diversity and genetic structure were obtained from 87 ISSR loci, while the mating system was analyzed using the MLTR software. Thirteen ISSR primers were selected that amplified 87 loci, with 100% polymorphism for the species. The primers with the highest efficiency in detecting polymorphism were CHRIS, M1, UBC 807, 818, 826, 829, 841, 842 and 857, considering the values of polymorphic information content, marker index and resolution power. The genetic diversity of Nei (H) averaged 0.31, and the Shannon index (I) averaged 0.47, with the greatest diversity occurring in the Bom Jesus progenies. The analysis of genetic structure showed a greater degree of genetic variation within populations (82.74%), and a value of Փst (0.17262), indicating moderate genetic structure between provenances. The UPGMA grouping (Unweighted Pair Group Method using Arithmetic) and the Bayesian Analysis (K=4) identified the formation of distinct genetic groups. The mating system is allogamous primarily, with a significant presence of progenies formed by crosses between relatives. These results reveal the importance of maintaining the ex-situ conservation of P. platycephala, with promising progenies for producing and propagating seeds for environmental purposes and genetic improvement of the species.