Mapeamento de QTLs associados à resistência a Alternaria alternata em híbridos de citros
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2016-08-29Autor
Campos, Kelly Aparecida Fernandes de
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Alternaria brown spot (ABS) disease is caused by a fungus of Alternaria genus, that
causes injury and fruit depreciation, leaves fall, drought of pointers and new shoots.
The action of the fungus Alternaria alternata f. sp. citri is directly associated by the
presence of toxin receptors on susceptible genotypes. The objectives of this study
were: (1) to characterize the phenotype of 264 citrus hybrids obtained from crossing
LPA Pera de Abril sweet orange (Citrus sinensis L. Osbeck) vs H163, a hybrid
between Murcott tangor (C. reticulata x C. sinensis) x Pera sweet orange (C.
sinensis), for response to A. alternata, via conidia suspension inoculation of detached
young leaves (in vitro) and (2) construction of a linkage map using DArT_seq
markers to identify possible QTL (Quantitative Trait Loci) associated to disease
resistance. The fungus was isolated from lesions of Murcott tangor fruits with ABS
symptoms and inoculated via conidia suspension on detached young leaves (in
vitro). Two hundred and thirty five hybrids were evaluated and 70 (30%) showed
different levels of disease symptoms after 72 hours of inoculation with the fungus on
detached leaves and 165 (70%) were asymptomatic. The integrated linkage map,
built with OneMap program, resulted in 726 DArT_seqTM and three SSR molecular
markers that covered nine linkage groups, corresponding to the haploid number of
chromosomes of the specie. Using the values of AUDPC, seven QTLs associated
with resistance to ABS were localized in linkage groups of the integrated map. The
integrated linkage map of Pera de Abril sweet orange (LPA) vs. H163 has a high
degree of synteny with pseudo-chromosomes of sweet orange (C. sinensis).