Genetic diversity and relatedness of selected Iranian rice cultivars and disease resistance donors assayed by simple sequence repeats and candidate defense gene markers

As a prerequisite to improving diseaseresistance and grain quality in Iranianrice cultivars, we determined the geneticrelatedness of popular local cultivars andblast-resistance donor germplasm usingfingerprints derived from simple sequencerepeat (SSR) and plant defense genemarkers. Fifty SSR markers and 28 defensecandidate genes were used to assess thegenetic diversity among popular ricecultivars from Iran and donors of blastresistance from breeding programs in Asia.Gene diversity estimate of the 16 corebreeding lines was 0.440 ± 0.028 basedon SSR markers. Genetic relationships amongthe cultivars were determined by clusteranalysis using SSR and candidate genedatasets. DNA fingerprints derived fromSSR and defense gene markers gave similargroupings of cultivars consistent withtheir genetic background: a) Iranian localvarieties, b) improved varieties in Iranplus donor indica germplasm from Asia, andc) japonica germplasm. Within-groupsimilarities for the traditional andimproved cultivars were greater than 80%and 75%, respectively. The traditional andimproved cultivars showed differentialreaction to blast pathogen isolates; alltraditional varieties were susceptible toblast pathogen isolates in Iran butresistant to isolates in the Philippines,whereas the improved varieties showedopposite reaction to pathogen isolates inIran and the Philippines. Both molecularand phenotypic data suggest a narrowgenetic basis in local and improvedcultivars in Iran and the need forincluding more diversity for the breedingprogram. The high degree of polymorphismobserved between local cultivars and donorsof blast resistance provide the neededinformation to follow the transmission ofresistance alleles from the donors inadvancing breeding lines.