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

Integumentary system - hair, HAIR Presence of hair is main feature ...

HAIR Presence of hair is main feature of mammals, absent in whale fish. Soft hair in embryo of animals are lanugo. Study of hair is tricology . Part of hair which

Respiratory system of the phylum annelida characterized, Q. How is the resp...

Q. How is the respiratory system of beings of the phylum Annelida characterized? Respiration in annelids can be branchial or cutaneous. Cutaneous respiration takes place due to

Alpha helix and the beta-sheet protein, What is the difference between the ...

What is the difference between the alpha helix and the beta-sheet protein conformations? Ans) Alpha helix and beta-sheet conformations are the two major types of secondary struc

Which are the glands present in the epidermis of mammals, Which are the gla...

Which are the glands present in the epidermis of mammals, birds and reptiles? In the epidermis of birds and reptiles there are almost no glands. In mammals there are sweat glan

What is respiration quotient, a) Where casparian strips situated in a plant...

a) Where casparian strips situated in a plant body are and what are they made up of? Mention its function. b) What is respiration quotient (RQ)? Under what conditions will th

Define absorption, Define Absorption, Storage and Elimination of Pyridoxine...

Define Absorption, Storage and Elimination of Pyridoxine? Pyridoxine, pyridoxal and pyridoxamine (along with their phosphorylated forms) occur in plant and animal foods. The ph

Indicator organism, a) What are the needsfor an organism to be an indicator...

a) What are the needsfor an organism to be an indicator organism? b)  In Australia, National Parks and coastal beaches attract various visitors during holiday periods.  EPA is

How are the lipids classified, Q. Concerning solubility, how are the lipids...

Q. Concerning solubility, how are the lipids classified? Oils and Fats are hydrophobic molecules, i.e., they are insoluble in water and non polar. Lipids in general are molecul

State the series of stimuli, State the series of stimuli ERPs a series ...

State the series of stimuli ERPs a series of stimuli such as tones or light flashes are presented to the participant, and the raw EEG for a precise one or two second period fol

Define serum vitamin a content, Define Serum Vitamin A Content? Assessm...

Define Serum Vitamin A Content? Assessment of serum vitamin A content is the most reliable criterion Tor assessing vitamin A status. Serum levels indicative of various degrees

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