RESUMO
Differential clones from submergence stress and control treatment from rice seedlings were isolated by the differential screening method. One of the clones, OsGAPDH, represented a gene that was expressed at high level during 12-h submergence. A homology search of GenBank databases showed that OsGAPDH had significant sequence homology with maize non-reversible glyceraldehyde-3-Phosphate dehydrogenase. The OsGAPDH sequence consists of 1,772 bp with the longest open reading frame encoding 499 amino acids with a calculated relative mass of 54.2 kDa. Genomic Southern analysis indicated that one or two copies of the OsGAPDH gene occur in the Yukihikari genome. The chromosomal location of the OsGAPDH gene was identified by RFLP analysis indicating that OsGAPDH was located on chromosome 8. Tissue-specific expression of OsGAPDH indicated that the high level of mRNA was detected in the panicle. Plants exposed to drought, submergence and ABA treatment showed an increased accumulation of OsGAPDH transcripts. The induction of Escherichia coli cells containing the pGST-OsGAPDH plasmid resulted in the accumulation of a large amount of the 83.2-kDa recombinant protein. The purified GAPDH enzyme showed an optimum activity at pH 8.5 and 50 degrees C, and was strongly inhibited by ATP and ADP.
RESUMO
A doubled haploid (DH) population derived from anther culture of F(1)'s between an Indica var. Zhai-Ye-Qing 8 and a Japonica var. Jing-Xi17 as well as two backcross populations derived from this DH population were used to investigate inheritance of the embryo sac abortion at early megagametogenesis occurring in Indica/Japonica rice crosses. Two major loci, dominant and complementaryesa-1 andesa-2, located on chromosomes 6 and 12 respectively, were detected. Genetic analysis indicated that embryo sac fertility is mainly regulated by the gametophytic genotype at these two loci.