Submitted to: Plant and Animal Genome Conference
Publication Type: Abstract Only
Publication Acceptance Date: October 30, 2009
Publication Date: N/A
Technical Abstract: Seedlessness is desirable for most citrus fruit, and identification of spontaneous or irradiated seedless mutants is important in developing citrus cultivars. We conducted a transcriptome analysis in early fruit development of three seedy citrus types (‘Fallglo’, a largely C. reticulata hybrid; ‘Pineapple’ sweet orange, C. sinensis; and grapefruit, C. paradisi) and their seedless mutants. Three trees of each seedy and seedless type were sampled on 4/17/09, 5/4/09, and 5/28/09. On each date from each tree 12-25 fruit were collected, with several assessed for seed abortion, while the remainder were immediately subjected to RNA extraction from entire fruits. Seed abortion was apparent in seedless mutants on the second collection date, 3-4 weeks after anthesis. RNA samples were pooled for the three trees of each seedy or seedless variant of each citrus type for each sampling date. RNA from these samples was analyzed using Affymetrix genechip citrus microarrays. Expression for 19,000-21,000 of the 30,171 gene probe sets was detected concurrently in seedy and seedless variants within each of the nine citrus type X timepoint combinations. Only seedy or only seedless variants displayed expression in 600-1800 genes for each comparison of seedy vs. seedless at each citrus type X timepoint, but no genes were consistently differentially regulated in seedy vs. seedless comparisons across all citrus types and timepoints. At a 3X threshold for difference in seedy vs. seedless gene expression, several differences were consistent across all seedy vs. seedless comparisons in each of the first two timepoints, suggesting possible association with seedlessness.