Passage of pollen tube, Biology

Assignment Help:

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.


Related Discussions:- Passage of pollen tube

What does genetics have to do with biology, What does genetics have to do w...

What does genetics have to do with biology? Genetics is the study of the genes found in genetic material (ex. DNA). DNA is found in the nucleus of your cells. The most signific

Codeine, CODEIN E - It is methylmorphine, obtained from opium. I...

CODEIN E - It is methylmorphine, obtained from opium. It is used in cough syrups. A notable side effect of codeine is constipation.

Human brain, what cause to hypertention?

what cause to hypertention?

Define sodium, Define Sodium, Potassium and Chloride - Minerals? Claude...

Define Sodium, Potassium and Chloride - Minerals? Claude Bernard was the first to draw attention to the internal environment (milieu interior), referring to the extracellular f

Health stroke scale, Health Stroke Scale: Stroke is a leading cause of...

Health Stroke Scale: Stroke is a leading cause of death, hospitalization, disability and health care expenditure in U.S. (Fonarow G. et al., 2012).  Stroke is a medical condit

Define criteria for assessment of riboflavin status, Define Criteria for As...

Define Criteria for Assessment of Riboflavin Status? Riboflavin status can be assessed by measuring urinary excretion of the vitamin in fasting, random, and 24-hour specimens o

Explain reality theory, Reality Theory Developed in  the 1960s by  Will...

Reality Theory Developed in  the 1960s by  Willian glasser,  a  psychiatrist,  reality  therapists  view human nature in terms of behaviour. They believe that human behaviour i

Physical weathering-weathering of rocks, Physical Weathering Mechanical...

Physical Weathering Mechanical forces acting upon the rocks cause physical weathering. Temperature fluctuations cause expansion and contraction of rock surface resulting in the

Explain le compte operation-rev procedure, Explain Le Compte Operation-REV ...

Explain Le Compte Operation-REV Procedure ? This is an alternative type of repair for TGA, VSD and left ventricular outflow obstruction (LVOTQ). In this operation an extrinsic

Pond sucession, make a assignment of pond succesion

make a assignment of pond succesion

Write Your Message!

Captcha
Free Assignment Quote

Assured A++ Grade

Get guaranteed satisfaction & time on delivery in every assignment order you paid with us! We ensure premium quality solution document along with free turntin report!

All rights reserved! Copyrights ©2019-2020 ExpertsMind IT Educational Pvt Ltd