GENETIC-MAPPING OF QUANTITATIVE TRAIT LOCI FOR PANICLE CHARACTERISTICS AND SEED WEIGHT IN SORGHUM

The objective of the sudy was to use restriction fragment length polym orphisms (RFLPs) to determine the genetic location and the inheritance of quantitative trait loci (OTL) controlling some morphological chara cteristics of the sorghum panicle, including panicle length, seed-bran ch length, sterile portion of the seed-branch, peduncle diameter, numb er of seed-branches per panicle, and 100-seed weight. F-2 plants (152) from the cross CK60 (Sorghum bicolor spp. bicolor) X PI229828 (S. bic olor spp. drummondii) were used. An RFLP map (111 loci distributed amo ng 10 linkage groups with an average of 12.9 cM between adjacent loci) was employed. interval mapping identified a total of 25 QTL: six for panicle length, five for seed-branch length, two for length of sterile portion of the seed-branch, six for peduncle diameter, three for numb er of seed-branches per panicle, and three for 100-seed weight. The '' high'' parent (with higher phenotypic mean) contributed to 64% of the alleles that increased the trait mean. QTL were unlinked, with no evid ence for epistasis. Phenotypic Variation for each QTL ranged from 8% t o 37%. Multiple models accounted for from 28% (100-seed weight) to 69% (panicle length) of the phenotypic variation. Pleiotropy or linked QT L was evident for panicle morphology traits. Positive significant corr elation coefficients corresponded to pleiotropic or closely linked QTL with the same direction of additive effects.