Submitted to: Seeds International Workshop Proceedings
Publication Type: Abstract Only
Publication Acceptance Date: December 7, 2001
Publication Date: February 8, 2002
Citation: Foley, M.E., Gu, X. Developing weedy rices for map-based cloning of dormancy genes. Seeds VII International Workshop on Seed Biology. May 12-16, 2002. Salamanca, SP. p.28.
As the first step for map-based cloning of seed dormancy genes from rice (Oryza sativa), we screened some domesticated and weedy strains for germinability of intact seeds, caryopses, pericarp/testa removed caryopses, and embryos; made several crosses; and began to characterized the genetics seed and caryopsis dormancy. Neither embryo nor endosperm-imposed dormancy detected in the 40 accessions that we screened. Germination of non-afterripened intact seeds from the dormant lines was 0% after 7 d of incubation. Therefore, we determined their germination following various periods of afterripening. Differences were detected in the number of days required to achieve ~50% germination of intact seeds. Fifty-five and 75 d o afterripening were required to achieve 50% germination of weedy strains 'LD and 'SS18-2', respectively. Dormancy was imposed mainly by the hull in 'SS18-2' and by both the hull and pericarp/testa in 'LD'. Estimates of broad-sense heritability (h2b) for intact seed germination varied with the cross and the duration of afterripening. At 20 days after harvest (DAH), h2 for germination of intact seeds was 0.94 and 0.95 for the cross 'CO39'/'SS18-2' and 'LD'/'WYJ', respectively. Heritability for caryopsis germination at 0 DAH for the above crosses was 0.34 and 0.82, respectively. detected three major genes for hull-imposed dormancy in 'SS18-2'. We are focusing on the 'SS18-2'-derived populations.