Abstract:
During the past two decades numerous papers
have been published on anther culture of rice. These
studies clearly indicate that while anther culture is a
technique that can be adopted for breeding japonica rice, it
being a useful adjunct in indica rice breeding is still some
way away. The main reasons why anther culture cannot be
utilized for indica rice breeding is analyzed, and aspects
that may be manipulated to achieve progress are presented
in this review. The two stages of rice anther culture, callus
induction and green plant regeneration, are genetically
determined traits that show quantitative inheritance. Indica
rice is known to have a recalcitrant genetic background that
supports these traits poorly. While improvement of the
genetic background through recombination or gene transfer
remains possible, manipulation of culture media, particularly
the nitrogen and carbon sources, has brought about
substantial improvements in indica rice anther culture.
Adjustments to pre- and post-culture conditions, that
include application of various stresses on anthers before
and after culture, also have had beneficial effects. The
importance of reducing the tissue culture phase to achieve
direct embryogenesis is discussed with special reference to
improving green plant regeneration potential. The necessity
to understand the processes involved in microspore
embryogenesis is highlighted in order to support empirical
knowledge and achieve a breakthrough in technology. In
this regard, rice genome sequence information may be
leveraged to elucidate functions of genes involved in
microspore embryogenesis.
