Development of an intergeneric hybrid between Oryza sativa L. and Leersia perrieri (A. Camus) Launert.

An intergeneric hybrid was successfully developed between Oryza sativa L. (IRRI 154) and Leersia perrieri (A. Camus) Launert using embryo rescue technique in this study. A low crossability value (0.07%) implied that there was high incompatibility between the two species of the hybrid. The F1 hybrid showed intermediate phenotypic characteristics between the parents but the plant height was very short. The erect plant type resembled the female parent IRRI 154 but the leaves were similar to L. perrieri. Cytological analysis revealed highly non-homology between chromosomes of the two species as the F1 plants showed 24 univalents without any chromosome pairing. The F1 hybrid plant was further confirmed by PCR analysis using the newly designed 11 indel markers showing polymorphism between O. sativa and L. perrieri. This intergeneric hybrid will open up opportunities to transfer novel valuable traits from L. perrieri into cultivated rice.

Starch Synthesis-Related Genes (SSRG) Evolution in the Genus Oryza.

Cooking quality is an important attribute in Common/Asian rice (Oryzasativa L.) varieties, being highly dependent on grain starch composition. This composition is known to be highly dependent on a cultivar's genetics, but the way in which their genes express different phenotypes is not well understood. Further analysis of variation of grain quality genes using new information obtained from the wild relatives of rice should provide important insights into the evolution and potential use of these genetic resources. All analyses were conducted using bioinformatics approaches. The analysis of the protein sequences of grain quality genes across the Oryza suggest that the deletion/mutation of amino acids in active sites result in variations that can negatively affect specific steps of starch biosynthesis in the endosperm. On the other hand, the complete deletion of some genes in the wild species may not affect the amylose content. Here we present new insights for Starch Synthesis-Related Genes (SSRGs) evolution from starch-specific rice phenotypes.

Evolutionary analysis of the SUB1 locus across the Oryza genomes.

BACKGROUND: Tolerance to complete submergence is recognized in a limited number of Asian rice (Oryza sativa L.) varieties, most of which contain submergence-inducible SUB1A on the polygenic SUBMERGENCE-1 (SUB1) locus. It has been shown that the SUB1 locus encodes two Ethylene-Responsive Factor (ERF) genes, SUB1B and SUB1C, in all O. sativa varieties. These genes were also found in O rufipogon and O nivara, wild relatives of O. sativa. However, detailed analysis of the polygenic locus in other Oryza species has not yet been made. FINDINGS: Chromosomal location, phylogenetic, and gene structure analyses have revealed that the SUB1 locus is conserved in the long arm of chromosome 9 in most Oryza species. We also show that the SUB1A-like gene of O. nivara is on chromosome 1 and that Leersia perrieri, a grass-tolerant to deep-flooding, presents three ERF genes in the SUB1 locus. CONCLUSION: We provide here a deeper insight into the evolutionary origin and variation of the SUB1 locus and raise the possibility that an association of these genes with flooding tolerance in L. perrieri may exist.