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 diabetes mellitus, Diabetes mellitm This anabolic hormone exert...

Diabetes mellitm This anabolic hormone exerts its action on key glycolytic  enzymes  thus  leading  to the conversion of glucose  to  pyruvate as explained under the regulation

Cornea - organogenesis of eye and limb, Cornea - Organogenesis of Eye a...

Cornea - Organogenesis of Eye and Limb The fully formed cornea contains 2-cell layered epithelium and the stroma made of extra cellular secreted materials. The bulk of the

Evolution, how to calculate the frequency of mating with the HW equation?

how to calculate the frequency of mating with the HW equation?

Illustrate the statment periodic access to food, Recognition comment: R...

Recognition comment: Recognises that food searching activity is more strongly controlled by access to food than light  through statements such as: birds always anticipat

Sp and spp., what is the deference between sp. and spp.?

what is the deference between sp. and spp.?

Polysaccharide sugars, Polysaccharide - polymer composed of monosaccharide...

Polysaccharide - polymer composed of monosaccharide monomers Starch - Energy storage in plants à straight (amylose) and branched (amylopectin) chains of α-glucose Glycogen

Cow-pox (vaccinia), C o w - po x (vaccinia) E p ide...

C o w - po x (vaccinia) E p idemiology: This infection, although mostly occurring in cows, sometimes also occurs in buffaloes. Under natural conditions, t

Explain risk assessment, Explain Risk Assessment Risk Assessment   :  ...

Explain Risk Assessment Risk Assessment   :  The scientific evaluation  of  known  or  potential adverse  health effects  resulting  from  human exposure to food borne hazards

Explain what is genetic engineering, Explain brifly what is Genetic Enginee...

Explain brifly what is Genetic Engineering ? Genetic Engineering : Engineering techniques have been used in agriculture and horticulture for centuries. Certain plants or ani

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