Histochemical insights into polysaccharide distribution during anther development in Swietenia macrophylla King.

Abstract

Carbohydrates are essential for anther development, serving as the primary energy source and
facilitating the differentiation of the anther wall, microsporogenesis, and pollen maturation. In this study
we have examined histochemical distribution of polysaccharides during successive stages of anther
development in Swietenia macrophylla King. using Periodic acid–Schiff (PAS) reagent. Results of the
study revealed that young anther primordia exhibited uniformly rich PAS-positive reaction. During
archesporial differentiation, connective cells contained starch grains, which later redistributed in anther
wall layers at the sporogenous stage. Microspore mother cells were moderately PAS-positive and
surrounded by an intensely PAS-positive callose wall. Microspores in tetrads and young microspores
exhibited moderate PAS staining in cytoplasm while nuclei and cell walls were richly PAS-positive.
The tapetum showed strong PAS-positive reaction at tetrads and young microspore stage which later
declined gradually during anther dehiscence. Vacuolated microspores and bicellular pollen grains
exhibited intense PAS positivity with progressive accumulation of starch grains. Mature pollen grains
contained abundant starch grains. Secretory cells of anther connective exhibited intense PAS-positive
reaction throughout anther development. However, the polysaccharide reserves of these cells gradually
depleted during anther dehiscence. Endothecium developed fibrious thickenings which showed PAS-
positive reaction. Polysaccharide dynamics in S. macrophylla anthers corresponded with physiological
activities occurring at successive stages of anther ontogeny, supporting the formation of functional
pollen grains.