Seed dormancy is an important adaptive mechanism to protect seeds under the unfavorable environments. Unlike to wild type species, the seed dormancy trait of cultivated crops has been weakened by breeding programs during the domestication period. Weak seed dormancy often causes preharvest sprouting (PHS) problem in many cereal crops that result in significant economic loss. The seed dormancy is a quantitative trait loci (QTL) controlled by multiple genetic and environmental factors. So far, many QTLs for seed dormancy have been identified from rice and wheat as well as in the model plant Arabidopsis. Unveiling of QTL genes and complex mechanisms underlying seed dormancy is accelerated by the rapid progress of crop genomics. In the present study, we reviewed current status of research progress on the seed dormancy QTLs and correlated genes in Arabidopsis and cereal crops.

Abscisic acid (ABA) is a stress hormone that functions in abiotic stress adaptation in plants. Thus many efforts have been made to identify the molecular mechanisms of ABA signal transduction pathways. Recently there were big advances in understanding molecular mechanisms of ABA dependent expression. From the ABA receptors to the transcription factors, signaling components were discovered and the biological networks among the components were identified. In this review, we describe the ABA signaling components and the rice orthologues identified. These show that signaling network systems of ABA are highly conserved in dicot and monocot plants and we are able to manipulate the ABA signaling components to develop the abiotic stress tolerant crops.