INFERÊNCIAS EVOLUTIVAS E IMPLICAÇÕES BIOMÉTRICAS EM Austropuccinia psidii (G. Winter) Beenken 2017

Abstract

Forest-based activity plays an important socioeconomic role in the country. Currently, Brazil is the leader in the rank of forest productivity, however, this high productivity has been affected by the constant attacks of pathogens that cause economic damage to these crops, an example is the myrtle rust caused by Austropuccinia psidii (G. Winter) Beenken, which has a wide geographic distribution and presents great genetic variability among its populations, attacking several species of the Myrtaceae family. In this sense, we sought to study population-genetic and evolutionary aspects of A. psidii populations. These data were about microsatellite loci for obtaining A. psidii isolates in about 148 populations of plants, from which they originated anddeposited in DRYAD. The model used in the estimates was of four subpopulations of A. psidii grouped based on seven hosts of the Myrtaceae family, being SPOP1 (Eucalyptus spp. + S. jambos), SPOP2 (P. guajava + P. guineense), SPOP3 (S. cumini) and SPOP4 (M. cauliflora and E. uniflora). These populations were formed from collections carried out by the authors of the deposits in the states of Bahia, Espírito Santo, Mato Grosso do Sul, Minas Gerais, Rio de Janeiro, Paraná, Santa Catarina, São Paulo, Rio Grande do Sul, in addition to Uruguay. Effective size and gene flow were estimated using the Bayesian inference method, based on the coalescence theory implemented in the MIGRATE-N software. In addition to descriptive statistics and graphs of population allelic patterns, paired estimates of FST and intra and intergroup differentiation by analysis of molecular variance (AMOVA) considering the genetic groups of four subpopulations and the seven hosts in a hierarchical manner. Gene flow (Nm) between population pairs was low (all < 1 unit), and ranged from 0.04 to 0.67. Estimates of effective population size (N and) were 119, 111, 189 and 1315 for SPOP1, SPOP2, SPOP3 and SPOP4 respectively. AMOVA showed that the percentage of variation was 39.43% between subpopulations, 16.29% between hosts within subpopulations and 44.28% within hosts. FST analogues were Φ CT = 0.394 (Among Subpopulations); Φ SC = 0.269 (Among Hosts within Subpopulation); Φ ST = 0.556 (Within the Hosts), in addition to high paired FST values that ranged between 0.355 and 0.560. The results obtained add knowledge about the understanding of A. psidii population genetics, proposing plausible scenarios in relation to the evolutionary and demographic past, as well as the processes that gave rise to the observed variability. Possibly the subpopulations of A. psidii will have different ecological behaviors and represent different invasive threats, being indicated studies that can measure the invasive risks presented by the different subpopulations. The work emphasizes the evident importance of genetic conservation in an adequate way in commercial species, aiming to guarantee the existence of resistant plant genotypes to be used in breeding programs, considering that resistance will be supplanted or reduced by the emergence of new races of A. psidii capable of adapting to the defenses present in the genotypes currently cultivated.