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

Define fluorides metabolism, Define fluorides Metabolism? Soluble fluor...

Define fluorides Metabolism? Soluble fluorides, even at high intake levels are almost completely absorbed from gastrointestinal tract. These include aqueous solutions of fluori

Isolating mechanism, In this section we are to discuss the means by which p...

In this section we are to discuss the means by which populations get separated or isolated from each other, first gain the status of'Sub-species and finally evolve mechanisms which

What role do catalysts play in chemical reactions, What role do catalysts p...

What role do catalysts play in chemical reactions? By decreasing the activation energy that is required for a reaction, a catalyst permits the reaction to proceed spontaneously

Main means by which autotrophic beings obtain energy, What is the main mean...

What is the main means by which autotrophic beings obtain energy? The major means by which autotrophs obtain energy is photosynthesis (There are also chemosynthetic autotrophs)

How to convert 3.5°f to celsius four hundred pounds, Convert 3.5°F to Celsi...

Convert 3.5°F to Celsius Four hundred pounds is how many kilograms?

What is defective colour vision, What is Defective Colour Vision Defect...

What is Defective Colour Vision Defective colour vision is often called colour blindness. The ability to appreciate one or more of the primary colours is lacking. This can be e

Determine the term - essential element, Determine the term - essential elem...

Determine the term - essential element It becomes difficult to meet all the conditions so as to establish essentiality. This is particularly so for the elements that are requir

Immunolocalization, uses and advantages and disadvantages of immunolocaliza...

uses and advantages and disadvantages of immunolocalization

Indicate the probability of producing, I have no idea how to do this: two g...

I have no idea how to do this: two gene loci, A and B, assort independently, and alleles A and B are dominant over alleles a and b. Indicate the probability of producing: an AB phe

What are the structures that form the external ear, What are the structures...

What are the structures that form the external ear? What is its function? The internal ear comprises the pinna, or auricle, and the auditory canal. Its function is to conduct t

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