Agriculture Reference
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Microspores with poor pollen wall
formation
Abnormal vacuolation
Cold
Rice plant
Reproductive
phase
Temperature
Hypertrophy of tapetum
Unusual starch accumulation in the
plastids of endothecium
Callose wall abnormalities during
tetrad release of anther
Fig. 24 Ultrastructure changes during cold stresses at reproductive phase.
this also contributes to other symptoms such as vacuolation
and poor microspore wall formation. Premature callose
breakdown apparently restricts the basic framework of the
future pollen wall. Vacuolation and hypertrophy are also
symptoms of osmotic imbalance triggered by reabsorption of
callose breakdown products due to absence of OsMST8 activity
(Mamun et al. 2009).
Low temperature (12ÂșC), for 4 days during microsporogenesis
and anthesis produced considerable sterility. Sensitivity was
greatest when the fl orets from the midsection of the panicle
were passing through the early microspore phase of pollen
development. The amount of low temperature induced sterility
was increased by high nitrogen supply (Heenan 1984).
Microspores are symplastically isolated in the locular space
of the anthers, and thus an unloading pathway of assimilates
via the apoplasmic space is mandatory for proper development
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