Loci affecting flowering time in oat under short-day conditions

Abstract

Flowering time (or days to heading) is an important characteristic in crop plants that affects adaptation to cropping cycles and growing seasons. The objectives of this study were to identify molecular markers associated with flowering time in 3 oat populations developed from Brazilian oat varieties, and to compare their map locations with those of other loci that might influence flowering time. Flowering time was studied in recombinant inbred lines from 3 hexaploid oat populations: UFRGS 8 x Pc68/5*Starter; UFRGS 881971 x Pc68/5*Starter; and UFRGS 8 x UFRGS 930605. Bulked segregant analysis, using amplified fragment length polymorphism, was followed by selective mapping in each population and in a reference population, 'Kanota' x 'Ogle' (KxO). One quantitative trait locus (QTL) with major effects on flowering time was identified in each cross. Comparative mapping showed that a major QTL, with earliness alleles originating from UFRGS 8 and UFRGS 881971, is in a region with close homology to KxO linkage group 17 and to a locus that reportedly confers day-length insensitivity in oat (Di1). This is the first report to identify the map location of the Di1 locus, and putatively confirm the presence of Di1 alleles in new germplasm. Further comparative mapping and the alignment of mapped oat markers with the sequenced rice genome suggest that this QTL and (or) Di1 is orthologous to the Hd1 locus in rice and the CONSTANS gene in Arabidopsis and other species. A different QTL with major effects segregated in the UFRGS 8 x UFRGS 930605 cross, where the early-flowering allele for Di1 was probably fixed. Two additional QTLs with smaller effects were identified in the UFRGS 8 x Pc68/5*Starter population. These results suggest that the Brazilian oat line UFRGS 8 contains an optimal set of alleles conditioning earliness under the short-day conditions of the Brazilian winter growing season, and that molecular selection could be used to introgress these alleles into other breeding material.

Molecular mapping of Pc68, a crown rust resistance gene in Avena sativa

“…The map covered 409.4 cM (14%) of the total Avena sativa genome, which is estimated to be 2900 cM (O'Donoughue et al 1995). However, this represents a significant expansion compared to the (Locatelli et al 2006), which covered only 4% of the total genome of the species.…”

“…To the polymorphic candidate markers that were identified, we added 34 markers that were previously identified by Locatelli et al (2006) in a study of flowering time in the same population. Chisquared tests were performed on each locus for goodness-of-fit to the expected 1:1 segregation ratio.…”

“…The markers that were obtained by Locatelli et al (2006) were added to the 80 polymorphic markers that were identified in our BSA analysis, resulting in a total of 114 AFLP molecular markers, which were tested on the F 6 inbred line population. The Mendelian segregation analysis showed that 77 (67%) of the marker loci segregated as expected for the F 6 inbred lines (1:1, a* = 0.05).…”

“…1). Secondly, when only the loci obtained by Locatelli et al (2006) were evaluated, the distortion was reduced to 26%. For the 80 markers obtained in this work, the restriction enzyme was PstI; however, for the 34 markers obtained by these authors, the enzyme was EcoRI, which is insensitive to methylation.…”

Comparative mapping of the oat Dw6/dw6 dwarfing locus using NILs and association with vacuolar proton ATPase subunit H

“…The protocol of Locatelli et al (2006) was used to identify amplified fragment length polymorphism markers (AFLP). Markers were selected for this study based on the Terra 9 Marion (T9M) (De Koeyer et al 2004) and Kanota 9 Ogle (K9O) (Wight et al 2003) recombination maps.…”