Microsatellite isolation and characterization in sunflower

PANIEGO, NORMA; MUÑOZ, MARIANNE; ECHAIDE, MERCEDES; FERNÁNDEZ, LUIS; FACCIO, PAULA; ZANDOMENI, RUBÉN; SUÁREZ, ENRIQUE Y.; HOPP, H. ESTEBAN

San Diego

Conferencia; VIII International Plant and Animal Genome Conference; 2000

Isolation and characterization of microsatellites markers in sunflower was performed using a non-enriched sunflower genomic library cloned in lambda phage vector. To this aim, hybridization screening has been performed using oligonucleotides probes containing different nucleotides arrays. 1200 microsatellites positive clones were sequenced and 268 PCR primer sequences bordering the microsatellite repeats were designed. For polymosphism assessment, 16 Helianthus annuus germplasm accessions were checked and 170 of the tested primers showed to be polymorphic for the selected lines with average Polymorphic Information Content (PIC) of 0.5. The most frequently motifs found within polymorphic SSR were: (GA)n (38%) and (GT)n (37%), followed by trinucleotides AAT (7.1%), TGG (6.5%) and ATC (4%) and the tetra nucleotide CATA (4%). Since not every motif was extensively screened for, and AT motifs were not screened, an extrapolation to the exact relative abundance as well as direct correlation between nucleotide motif and polymorphism degree can?t be inferred. Based on the results of the screening and their representation on the genomic library, the estimated average distance between SSRs containing GT and GA motifs were 250 an 315 kb respectively, inferring a total microsatellite number of 1.1x104 GT and 9.5x104 GA in the sunflower genome. In spite of the AT motif was not screened for, it was abundantly found in association with other motifs specially GT. Moreover, the average estimated distance between AR rich motifs and ATT, ATC and CATA was calculated in 918 kb. Taken together, an important representation of AT rich motifs in the sunflower genome can be assumed. Most of the 170 SSR obtained showed important differences in the 16 inbreed lines used for this characterization. Regarding its polyalelism they have a great potential for variety fingerprinting and molecular breeding