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

Protect a species from extinction, In what ways can we try to protect a spe...

In what ways can we try to protect a species from extinction? We can attempt to protect species from extinction by making it illegal to kill the threatened animals or uproot o

Types of nursing units, TYPES OF NURSING UNITS: The design of nursing ...

TYPES OF NURSING UNITS: The design of nursing unit should maximize the function of the unit by following its task. The design of nursing unit has also under gone a radical cha

Agro industrial-complication during gestation, Complication during gestatio...

Complication during gestation Many complications like uterine torsion, vaginal prolapse, mummification, foetal maceration, hydra allantois, hydro amnios and teratological abno

Explain about vitamin k, Vitamin K (Menadione - Vitamin K3, oil soluble) ...

Vitamin K (Menadione - Vitamin K3, oil soluble) Menadione is a yellow, lustrous, crystalline powder. It is easily soluble in benzene, soluble in fats and fatty oils.  It is spa

List out points about the traditional food preservation, List out Points ab...

List out Points about the Traditional Food Preservation? 1. The traditional food preservation methods like drying, pickling, salting, smoking, canning and freezing have been wi

How will this increase survival, Why would we evolve so that when we are st...

Why would we evolve so that when we are stressed our immune system is suppressed? How would this increase survival?

Define fraction in which calcium in plasma is present, Define Fraction in w...

Define Fraction in which Calcium in plasma is Present? Calcium in plasma is present in three major fractions: Ionized calcium Protein bound calcium Complexed c

Juxtaglomerular apparatus, Normal 0 false false false E...

Normal 0 false false false EN-IN X-NONE X-NONE MicrosoftInternetExplorer4

Define age as a determinants of nutrient requirements, Define Age as a dete...

Define Age as a determinants of nutrient requirements? Age: Requirements change with increasing age between birth and maturity. Nutrient requirements per unit body weight are h

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