Passage of pollen tube, Biology

Passage of Pollen Tube

In cotton, the pollen produces a tube within an hour which grows on the surface of the stigmatic hairs, and then between the cells of the stigma at the bases of hairs and beyond. The cytoplasm of the stigmatic hair degenerates; no exudate is secreted. The tube continues growth through the intercellular spaces of the thin-walled cells of transmitting tissue. After reaching the thick-walled cells of the main strand, it actually grows through wall layer 3. It has been reported that pollen tube of Petunia grows within the compact matrix of the middle lamella of the transmitting tissue by enzymatically creating a pipe-like path in front. By the increased dictyosome activity the cells become thicker. Callose is deposited in the pit fields on the transmitting tissue after the passage of pollen tube.

The pollen tube passage probably changes the permeability of cells and callose is formed as a wound response and as a reaction against cell leakage. Once the pollen germinates and the pollen tube has penetrated the stigmatic tissue, the path of the pollen tube through the rest of the stigma and style appears to be determined by the nature and structure of the cell walls and the morphology and distribution of the transmitting tissue. The nutritive role of the transmitting tissue was recognized early. Pollen tubes of Lilium, Petunia and Oenothera are shown to draw nourishment (sugar and amino acids) from the stylar tissue. Growth of tubes through style causes an increased inflow of carbohydrates into the pistils. In Aegle marmelos the cells surrounding the stylar canals show an optimal concentration of starch just before pollination, subsequently as the starch is digested, the canal cells and the basal portions of the stigmatic papillae show reducing sugars which also disappear within 3 days after pollination. Disappearance of stylar starch has also been observed in Fritillaria, Zephyranthes and Pavonia.

Posted Date: 1/23/2013 4:26:55 AM | Location : United States

Related Discussions:- Passage of pollen tube, Assignment Help, Ask Question on Passage of pollen tube, Get Answer, Expert's Help, Passage of pollen tube Discussions

Write discussion on Passage of pollen tube
Your posts are moderated
Related Questions
Q. Despite having a great biodiversity why is the Amazon Rainforest under risk of desertification? The natural soil of the Amazon Rainforest isn't very fertile but it is enrich

Q. Explain the Bone Implant Interface? Three phases have been described in the development of bone implant interface. 1. Stabilization phase Subendosteal and subperiost

Buccal Perforations Buccal concavities in the bone can result in some threads of the implant being exposed. Where these are very circumscribed and covered with thick and well-

description of first five phylum

Q. Explain about Glycemic Index? Although the use of exchange lists is still popular for planning diabetic diets, it has been realized in recent years that in exchange lists th

Q. Why isn't the cooking of vitamin C-containing foods appropriate for vitamin C supply? To obtain vitamin C, for instance, from an orange dessert, the vitamin- containing food

Q. What is the nitrogen cycle? The nitrogen cycle represents the recycling and circulation of the chemical element nitrogen in nature. The nitrogen cycle fundamentally depends

Blood Salvage and Bloodless Open-heart Surgery: At the time of cardio pulmonary bypass, cardiomony suckers suck blood from the chambers or the heart and pericardium back into the

NAILS - Cover terminal segment of fingers & toes. Highly vascular dermis under lying the nail is called nail bed . It gives pinkish colour to nail. The small part

BACK CROSS When F 1  individual (Tt) is crossed with one of the two parents, either tall (TT) or dwarf (tt), such a cross is called the back cross. There are two possibilities