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

Composite endosperm - variants of endosperm, Composite Endosperm - Variants...

Composite Endosperm - Variants of Endosperm In the family Loranthaceae, the development of endosperm is unique. The ovary lacks ovules. The sporogenous tissue located at the b

Explain three parts of homogenate, Differential centrifugation divides cell...

Differential centrifugation divides cellular components based on the differences in their size and / or density. A tissue sample was homogenized and three parts (aliquots) of this

What are plasmids, What are plasmids? Plasmids are circular DNA molecul...

What are plasmids? Plasmids are circular DNA molecules there in the genetic material of some bacteria. They might be containing genes responsible for bacterial resistance to so

Reproduction, Normal 0 false false false EN-IN X-NONE...

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

Horse diseases-borna disease, Borna disease Borna disease is fatal neurolo...

Borna disease Borna disease is fatal neurological disease of horses and sheep caused by a virus (RNA) of the family Bornaviridae and the disease is characterized by sub acute meni

Patient and probe positioning, Patient Positioning The patient  should...

Patient Positioning The patient  should be  in  the  left lateral position as  this brings the heart into contact with chest wall. The left arm is extended behind  the head  t

Populations of predators and prey vary in predatism, Q. How do populations ...

Q. How do populations of predators and prey vary in predatism? Whenever a predator population enhance at the first moment the prey population tends to reduce. At a second momen

Bovine rotavirus diarrhoea, B o v i ne rotavirus diarrhoea The bovi...

B o v i ne rotavirus diarrhoea The bovine rotavirus is a RNA virus with 11 segments of double stranded RNA belonging to the genus Rotavirus in the family Reoviridae. Rotavi

Coadapted communities, From your studies in ecology, you must be aware that...

From your studies in ecology, you must be aware that most ecosystems are quite complex consisting of several habitats and that habitats in turn are composed of microhabitats. Each

Explain tertiary butylhydroquinone, Tertiary Butylhydroquinone (TBHQ) T...

Tertiary Butylhydroquinone (TBHQ) TBHQ is moderately soluble in oil and slightly soluble in water. In many cases, TBHQ is more effective than any other antioxidant in providing

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