ABSTRACT
The development of suspensor in Brassica campestris is of the "Onagrad type"; The suspensor growth was maximum between the globular and heart stage of embryo development. There after, the suspensor diminished and immediately after the torpedo stage, it degenerated several enzymes (e.g. acid-, alkaline-, adenosine triphosphatase, peroxidase, succinate dehydrogenase, cyotchrome oxidase) and general substances (ascorbic acid, polysaccharides, lipids) were localized in the suspensor during different phases of embryo growth. Between the globular and heartshaped stage, suspensor cells had strong reaction. An attempt is made to elucidate possible physiological functions in relation to specific enzyme localization. The possibility of suspensor having secretory function is also brought out. Present histochemical data indicated that suspensor was chiefly concerned with absorption and transport of metabolites from the surrounding tissue to the developing embryo.
Subject(s)
Plants/embryology , Histocytochemistry , Plants/analysis , Plants/enzymologyABSTRACT
Using histochemical techniques, changes in the localization of different reserve substances (e.g. pectic compounds, starch, polysaccharides, proteins, nucleic acids, ascorbic acid) and enzymes (Acid phosphatase, alkaline phosphatase, ATP-ase, 5-nucleotidase, esterase, phosphorylase, succinate dehydrogenase, cytochrome oxidase and lipase) have been studied in the young and fertilized ovules of Zephyranthes sp. and Lagenaria sp. etc. Extensive changes in the enzyme activity and reserve substances are demonstrated during megasporogenesis and megagametogenesis and most of the substances exhibited interesting distributional pattern. Similarly, all the enzymes investigated have specific locale of distribution in the tissues which displayed differentiation of embryo sac. The earlier changes observed are in the megaspore which contained many reserve substances (starch; nucleic acids; ascorbic acid; proteins) and enzymes (peroxidase, succinate dehydrogenase, acid phosphatase, alkaline phosphatase and ATP-ase). In the matured embryo sac different cells have differential localization of the substances. Based on histochemical studies, distinct differences are made out between egg and synergids; egg and central cell. In general antipodals have maximum accumulation of physiologically active substances and intense activity of different enzymes. Nucellus cells also stored diverse substances and enzymes especially towards the chalazal end. Pollination stimulated accumulation of several reserve substances and enzymes in the tip of nucellus beak, micropylar zone and these included starch, peroxidase, phosphorylase succinate dehydrogenase, cytochrome oxidase etc.
