Submitted to: Plant Genome Conference Proceedings
Publication Type: Proceedings
Publication Acceptance Date: 10/1/2003
Publication Date: 1/13/2004
Citation: Trebbi, D., McGrath, J.M. 2004. Molecular phenotyping for discovery of candidate genes residing in sucrose accumulation QTL regions of sugar beet (Beta vulgaris L.). Plant Genome XII Proceedings. Available: http://www.intl-pag.org/pag/12/abstracts/P7b_PAG12_881.html.
Technical Abstract: Genes that play major roles in root sucrose accumulation in sugar beet (Beta vulgaris L.) are largely uncharacterized. QTL analysis was performed on root sucrose content, root dry matter, root size and shape, and yield. Traits were evaluated in greenhouse-grown F2 plants and on field-grown F3 families. A genetic map of the F2 population from a single sugar x red beet infra-specific hybrid, spanning a total of 558 cM, was constructed using 306 AFLP, RFLP, SSR and phenotypic markers. Several QTL were detected throughout the 9 linkage groups for each trait. Differential gene expression profiles of greenhouse-grown sugar beets from 2 to 10 weeks after emergence (WAE) period were determined at weekly intervals. Sucrose began accumulating in roots at the fifth WAE, and of the 3302 cDNA-AFLP fragments scored, 1121 (34%) were differentially expressed over this 8-week period. Of these, 20% were unique to either early or late stages, and 16 amplified fragments were only expressed at the beginning of the sucrose accumulation phase. Root mRNA from 4 and 8 WAE plants was hybridized to an Arabidopsis cDNA-microarray carrying 14,562 sequences and, among others, expected increase of expression in both sucrose synthase (SuSy) and sucrose transport (SUC2)genes was observed at eight WAE. Identification of candidate genes for co-localization of QTL on the genetic map appears to be facilitated by gene expression profiling anlayses.