Abstract

The present study was conducted in five Gossypium mustelinum populations that were phenotyped and genotyped to quantify their resistance to the major diseases that affect cultivated cotton (G. hirsutum) in Brazil. Four G. mustelinum populations, in addition to genotypes of G. hirsutum and G. barbadense (resistant or susceptible controls), were phenotyped for resistance to cotton blue disease, angular leaf spot, common mosaic and ramulose. Artificial inoculation of cotton plants with causative agents of cotton blue disease, angular leaf spot and ramulose, as well as those naturally infested with common mosaic virus, showed that all G. mustelinum accessions were susceptible to every disease studied. Four microsatellite markers linked to disease resistance genes for cotton blue disease, angular leaf spot and root-knot nematodes (Meloidogyne spp.) in G. hirsutum were used for genotyping of the five populations. The markers amplified different alleles from those associated with resistance genes in cultivated cotton, revealing polymorphisms different from reported cases of G. hirsutum resistance. The susceptibility to all diseases studied may represent a phytosanitary risk for the in situ conservation of natural G. mustelinum populations.

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