Pre-harvest sprouting and grain dormancy in sorghum bicolor: What have we learned?

RODRÍGUEZ, MARÍA V.; BENECH-ARNOLD, ROBERTO L.

Frontiers in Plant Science

FRONTIERS MEDIA S.A.

Año: 2018 vol. 9 p. 1 - 8

The possibility of obtaining sorghum grains with quality to match the standards fora diversity of end-uses is frequently hampered by the susceptibility to pre-harvestsprouting (PHS) displayed by many elite genotypes. For these reasons, obtainingresistance to PHS is considered in sorghum breeding programs, particularly whenthe crop is expected to approach harvest maturity under rainy or damp conditionsprevalence. As in other cereals, the primary cause for sprouting susceptibility is alow dormancy prior to crop harvest; in consequence, most research has focused inunderstanding the mechanisms through which the duration of dormancy is differentiallycontrolled in genotypes with contrasting sprouting behavior. With this aim two tanninless, red-grained inbred lines were used as a model system: IS9530 (sprouting resistant)and Redland B2 (sprouting susceptible). Redland B2 grains are able to germinate wellbefore reaching physiological maturity (PM) while IS9530 ones can start to germinate at40?45 days after pollination, well after PM. Results show that the anticipated dormancyloss displayed by Redland B2 grains is related reduced embryo sensitivity to abscisicacid (ABA) and increased levels of GA upon imbibition. In turn, transcriptional datashowed that ABA signal transduction is impaired in Redland B2, which appears to havean impact on GA catabolism, thus affecting the overall GA/ABA balance that regulatesgermination. QTL analyses were conducted to test whether previous candidate geneswere located in a dormancy QTL, but also to identify new genes involved in dormancy.These analyses yielded several dormancy QTL and one of them located in chromosome9 (qGI-9) was consistently detected even across environments. Fine mapping is alreadyin progress to narrow down the number of candidate genes in qGI-9.