A RAPD marker linked to the resistance gene to Alternaria leaf spot ( Alternaria mali Roberts) in 'Qinguan' apple.

摘要

Resistance to Alternaria leaf spot in an F₁ population of the cross of 'Qinguan' x 'Fuji' and its reciprocal cross 'Fuji' x 'Qinguan' was determined under natural conditions in 2006 and 2007. Among the progenies of both crosses, the SI values revealed some genetic features of quantitative traits demonstrating a continuous bi-modal distribution. This indicates that Alternaria leaf spot resistance in these two crosses may be controlled by a major gene in combination with some minor genes. Forty resistant, thirty-one susceptible progenies of the cross 'Qinguan' x 'Fuji' and 325 RAPD primers were chosen to detect markers linked to resistance based on the Bulked Segregant Analysis (BSA). A fragment, S428-854, present in 'Qinguan' and the resistant DNA pool, and absent in 'Fuji' and the susceptible DNA pool was obtained from the amplification by the primer S428. The distribution of S428-854 marker in F₁ individuals showed that the molecular data of 56 individuals (78.9%) were consistent with the field resistance phenotype data. The S428-854 RAPD marker was sequenced and found to be 854 bp in length. Results of BLAST searches with this sequence in the NCBI database indicated that its homology to known sequences was no more than 30%. Structure analysis using DNASTAR software showed that this sequence did not have an open read frame, meaning that it does not have a complete gene structure. We have submitted this sequence to NCBI GeneBank as accession EU710766.