Sporophytic incompatibility, Biology

Assignment Help:

Sporophytic Incompatibility

The recognition and rejection reactions in a SSI system occur on the stigma surface, placing barriers for pollen germination or penetration of pollen tube into the stigma. Thus the pollen grains either fail to germinate or the small tube they put out is inhibited by callose deposition at the tip. The papillae at the stigma also develop a lenticular callose plug within 10 min after pollination. Infact, in incompatible cases, inhibition of varying degrees operates at every level starting from pollen adhesion, hydration, germination and tube entry into the stigma. In some plants stigma is covered with a cuticular layer such that the incompatible pollen tube fails to penetrate.

Various studies have proved the necessity of enzyme cutinase in eroding the cuticle. This enzyme is activated only by the compatible cases. Incompatible stigmas may lack copious exudate, but dry stigmas have a hydrated layer called pellicle over the cuticle. This pellicle consists of a lipid layer where a mosaic of proteins floats. The pellicle probably originates by the protrusion on the surface of the papillae through discontinuities in the cuticle. As soon as pollen is received by the stigmatic surface the papillate cells exude moisture. The incompatibility is the result of interaction between protein fractions of exine and stigma.


Related Discussions:- Sporophytic incompatibility

Explain in detail about male reproductive system, Explain in detail about M...

Explain in detail about Male Reproductive System The male reproductive organ consists of the following:  A pair of testes, held in scortum; produces spermatooa and testoster

Define single beam and double beam optical path, Define Single Beam and Dou...

Define Single Beam and Double Beam Optical Path? In simpler instruments, a single beam of light passes through the cuvettes and reaches the detector whereas in the double beam

What is the phototropism, What is the phototropism? The Phototropism is...

What is the phototropism? The Phototropism is the movement of plant structures in response to light. The Phototropism may be negative or positive. The Positive phototropism is

Management goals for diverticular disease, Q. Management goals for divertic...

Q. Management goals for diverticular disease? The management goals discussed above are basic to prevention of diverticulitis. However, diet therapy during diverticulitis may b

Why some trees lose their green color in the autumn, Q. Why some trees lose...

Q. Why some trees lose their green color in the autumn? In autumn nights longer and days become shorter thus there is a reduction of the photosynthesis rate and some plants pre

Temperature affecting the growth of microorganism, Temperature is one of th...

Temperature is one of the important factors affecting the process of growth in bacteria, as it has a bearing on chemical reactions. The temperature at which the maximum growth occu

Describe the main cycle in metabolism of cornea, Describe the main cycle in...

Describe the main cycle in metabolism of cornea. Main Cycle: Glycolysis is represented by the central chain and involves the anaerobic conversion of glucose into pyruvic

Define the term- brain circuitry underlying addiction, Define the term- bra...

Define the term- brain circuitry underlying addiction By unraveling brain circuitry underlying addiction, scientists have identified new targets for therapies which might quell

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