Abstract

MOLINA, Sandy et al. Genetic diversity of Phytophthora spp. from Venezuelan cacao plantations by ISSR markers. Rev. Protección Veg. [online]. 2016, vol.31, n.1, pp. 1-8. ISSN 2224-4697.

Phytophthora spp. comprises four species responsible for canker of the trunk and black pod of cacao (Theobroma cacao L.) in Venezuela. Pytophthora palmivora (E.J. Butler) E.J. Butler is the most widely distributed species, followed by Pytophthora megasperma Drechsler, Pytophthora capsici Leonian, and Pytophthora citrophthora (R.E. Sm. & E.H. Sm.) Leonian. In order to understand the genetic basis of the population of Phytophthora spp. on cacao, its diversity was analyzed by ISSR molecular markers. Samples from the three main cocoa growing areas of Venezuela were collected. Forty nine isolates were morphologically identified at the genus level, from which genetic profiles were generated with three out of six, ISSR primers (880, 888 and 890). A matrix 49x55 was analyzed by Principal Coordinates Analysis (ACoP), Cluster Analysis and External Logistics Biplot (BLE). The ISSR primers allowed the construction of the genetic fingerprinting of the isolates; it showed no association with the site of origin. The ACoP distinguished three main groups, which could be predictive of at least three species, which in turn would be the most frequently affecting cocoa plantations in the country. At the same time, BLE enabled us to identify that, of the total of 55 amplified fragments, only three bands of the primer 888 (1.400pb, 3.200pb, and 4.600pb) were directly involved in the separation of the groups. Thus, BLE showed not only the relationship among isolates, but at the same time the relationship between isolate-allele and allele-allele.

Keywords : cacao; ISSR; diversity; Phytophthora.

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