Agriculture Reference
In-Depth Information
of pollen. Antisense repression of the anther specifi c cell wall
invertase or interference with invertase activity by expressing
a proteinacious inhibitor under the control of anther-specifi c
invertase promoter results in a block during early stage of
pollen development, thus causing male sterility without having
any pleiotropic effects. Restoration of fertility was successfully
achieved by substituting the down-regulated endogenous plant
invertase activity by a yeast invertase fused with the N-terminal
portion of potato derived vacuolar protein proteinase II (Pi
II-Scsuc2), under control of the orthologous anther specifi c
invertase promoter Nin88 from tobacco (Engelke et al. 2010).
In rice, a female archesporial cell elongates longitudinally
and directly differentiates the megasporocyte or megaspore
mother cell (MMC). The MMC then undergoes meiosis,
resulting in the formation of four haploid spores. A chalazal
spore becomes a functional megaspore, where as three spores
toward the micropyle undergo programmed cell death.
In the majority of the fl owering plants, the dynamic phase
transition of sporophyte to gametophyte occurs in the anther
and ovule. Sporogenosis is characterized by the differentiation
of hypodermal cells in anther and ovule primordia, termed
primordial germ cells or archesporial cells, into microsporocytes
and megasporocytes and megaspores, in which a differential
pattern of spore formation between male and female organs
called heterospory, usually observed in flowering plants,
including rice. Low temperatures during this stage disrupt
proper pollen developments, leading to a shortage of sound
pollen at the fl owering stage (Satake 1976, Farrell et al. 2006).
CSIRO is determining the molecular basis of pollen sterility
in rice. Cold repress sugar transport to the pollen grains,
causing abortion of pollen development. Two important genes
that are involved in sugar transport have been identifi ed and
