Reproductive characterization of P. coloratum var. makarikariense - INTA Rafaela germplasm

ARMANDO LORENA VANESA; CARRERA ALICIA DELIA; TOMAS MARÍA ANDREA

Buenos Aires

Simposio; 5th International Symposium of Forage Breeding (ISFB 2015); 2015

Panicum coloratum var. makarikariense is a perennial C4 grass native to Sud Africa used as forage in tropical and subtropical regions around the world. Recent interest in breeding strategies for this species requires a better understanding of the reproductive biology. The objectives of this study were i) to estimate and compare seed production and seedling survival under self and cross-pollination, and ii) to characterize the progeny of selected plants using SSR markers. Based on number of mature seeds, germination and seedling survival assays, the probability of seed production and seedling survival for self and cross-pollinated panicles was estimated using the method of Conditional Probability: p(A˄B) = p(A) x p(a/b). DNA was extracted using a modified SDS method from 12-15 seedlings selected at random from the progeny of three defined single plants. Ten gSSRs and EST-SSRs were searched for polymorphisms between maternal and progeny plants. Each band was vi­sually scored as either absent (0) or present (1), and the genetic variation within families was estimated using GenAlex 6.5 program. For mature seeds, the probability of coming from a cross-pollinated panicle was higher than from a self-pollinated one (92 vs 8%). The probably of survival for a 40-days-old-plant was higher when coming from cross-pollination (32%) than self-pollination (6%). The probability of finding a plant obtained by cross-pollination was significantly higher (97%) than by self-pollination (3%). The SSR progeny tests showed that 83% of the F1 presented private alleles (8 to 11) and none in the offspring was identical to the maternal genotype for all loci analyzed. Genetic variability in the progenies was over 50%. However, even in low proportion, some plants produced mature seeds by self-pollination. The sum of all results suggests that P. coloratum is a species that closely depend on cross-pollination for obtaining viable offspring. Knowledge of the reproductive behavior is critical when considering strategies for germplasm collection and conservation, to predict gene flow and patterns of inheritance and for the development of breeding programs, especially when designing crosses of related materials.