Scientists have attempted to develop and improve grain
quality through classical breeding as well as biotechnology.
A nice example is the down-regulation of ALK in
rice using an RNAi approach which results in changes in
gelatinization temperature and gel consistency (Gao et al.
2011). However, extra care has to be taken as downregulation
or up-regulation of the expression of a single
gene might result in unpredictable and complex biochemical
and physiological changes. It has been reported that
modification of a single starch synthesis gene led to
could be compensated for by increases in other proteins
(Kawakatsu et al. 2010a).
Although significant efforts have been made, future
research on grain quality in rice will continue to study
functions of genes including regulators of seed-storage
proteins and starch synthesis, as well as identifying regulators
of transporters involved in assimilate uptake, and
screening for receptors and components of relevant developmental
and environmental stress pathways.
Meanwhile, newly developed technologies, such as nextgeneration
sequencing which allows resequencing and
genotyping of large collections of rice cultivars and the use
of the data in Genome-Wide Association Studies (GWAS)
(e.g., Huang et al. 2010), have provided us with advanced
molecular and genetic approaches to identify gene and
marker-trait associations. Integration of proteomic, transcriptomic,
metabolomic, and phenotypical information
will help scientists to describe a comprehensive model on
the development of the grain and a better understanding of
how the composition of the storage materials in the endosperm
is linked and determined by endogenous developmental
and exogenous signals and factors.