Submitted to: Plant Molecular Biology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 9/28/2009
Publication Date: 10/13/2009
Publication URL: http://hdl.handle.net/10113/43761
Citation: Gu, X., Liu, T., Feng, J., Suttle, J.C., Carter, C., Gibbons, J. 2010. The qSD12 Underlying Gene Promotes Abscisic Acid Accumulation in Early Developing Seeds to Induce Primary Dormancy in Rice. Plant Molecular Biology. 73:97-104. doi: 10.1007/s11103-009-9555-1. Interpretive Summary: Premature loss of seed dormancy results in pre-harvest sprouting which reduces harvestable grain yield and quality thereby reducing producer’s profits and compromising the nutritional value of the harvested product. Seeds acquire primary dormancy during their development in order to maintain an arrested state and the length of this dormant period is dependent on both environment and genotype. Currently many genetic markers have been associated with seed dormancy in cereals but their actual function in many cases remains unknown. In this paper, the identity of a major genetic marker controlling seed dormancy in rice was determined by a combination of techniques including mapping and marker-assisted analysis. The genetic region involved in dormancy control was shown to contain 3 possible genes, each of which is a candidate for the dormancy control gene. Further analysis indicated that the gene responsible for seed dormancy may act by regulating the synthesis or action of a major plant hormone abscisic acid. Further studies are underway to determine the exact function of the gene identified.
Technical Abstract: Seeds acquire primary dormancy during their development and the phytohormone abscisic acid (ABA) is considered to play a role in inducing the dormancy. qSD12 is a major seed dormancy QTL identified from weedy rice. This research was conducted to identify qSD12 candidate genes, isolate the candidates from weedy rice, and determine the relation of the dormancy gene to ABA. A fine mapping experiment, followed by marker-assisted progeny testing for selected recombinants, narrowed down qSD12 to a genomic region of <75 kb, where there are 9 predicted genes including a cluster of 6 transposon/retrotransposon protein genes and 3 putative (a PIL5, a hypothetic protein, and a bHLH transcription factor) genes based on the annotated Nipponbare genome sequence. The PIL5 and bHLH genes are more likely to be the QTL candidate genes. A BAC library equivalent to 8-9 times of the haploid genome size was constructed for the weedy rice. One of the 2 BAC contigs developed from the library covers the PIL5 to bHLH interval of the narrowed QTL region. A pair of lines different only in the QTL-containing region of <200 kb was developed as isogenic lines for the qSD12 dormancy and non-dormancy alleles. The dormant line accumulated much higher ABA in 10-d developing seeds than the non-dormant line. On the QTL-containing region there is no predicted gene that has been assigned to ABA biosynthetic or metabolic pathways. Thus, it is concluded that the qSD12 underlying gene promotes ABA accumulation in early developing seeds to induce primary seed dormancy.