Submitted to: Crop Science
Publication Type: Proceedings
Publication Acceptance Date: March 25, 2014
Publication Date: N/A
Technical Abstract: Sorghum (Sorghum bicolor L. Moench) cultivars and germplasm display branched inflorescence or panicle, characterized by spikelets composed of a single sessile, fertile floret that develop into viable seed and one or two adjacent sterile pedicellate florets (Monoseeded [MSD] trait). Based on total number of florets per panicle, most sorghum germplasm and cultivars exhibit between30-40% seed set. Here, we report the isolation and characterization of a stable and recessive multi- seeded mutant (msd1) in sorghum (BTx623 background, WT) which produces fertile sessile and pedicellate florets that develop into seeds resulting in increased seed set from 40 to 90% and had greater number of primary and secondary panicle branches. Pedicellate florets of msd1 exhibited complete flowers with 70-95% functional gynoecium and androecium compared to none (0%) in WT. This alteration in flower development in msd1 mutant resulted in approximately tripling the seed number and a significant increase (30-40%) in total seed weight per panicle compared to WT. Additionally, msd1 mutant displayed increased overall panicle length, number of primary and secondary inflorescence branches per panicle. The msd1 seeds are smaller as reflected by lower seed weight as possible trade-off from the increased seed number. However, msd1 plants produced greater overall total seed weight per panicle. msd1 plants backcrossed once (BC1F2) to WT, displayed normal developmental processes, complete reproductive stage, and showed similar germination rate as WT. We hypothesize that the multi-seeded phenotype described here could be a result of an alteration of a major genetic switch that controls/regulate gynoecium, androecium development and panicle branching in Andropogoneae.