SSRG evolution in the genus Oryza
Keywords: Leersia perrieri, phylogeny, starch synthesis, cooking quality.
Background: Cooking quality is an important attribute in Common/Asian rice (Oryza sativa 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
Findings: 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 speci c
steps of starch biosynthesis in the endosperm. As observed in O. sativa subsp. japonica, the lower
amylose content is probably related to the absence of a C-terminal domain in PUL, characterizing what
we know as japonica genotypes. On the other hand, the complete deletion of some genes in the wild
species do not affect the amylose content, as observed in the absence of GBSSII in starch biosynthesis of
O. meridionalis, SSIV2 in O. glaberrima and DPE1 in O. brachyantha and O. nivara in which such
modi cations seem not to affect the nal endosperm starch composition.
Conclusion: Here we present new insights for obtaining new starch-speci c rice phenotypes, considering
structural protein features that include both the absence and duplication of copies, once again denoting
that Oryza species are a rich source of variability for use in plant breeding.