Already have an account? Get multiple benefits of using own account!
Login in your account..!
Remember me
Don't have an account? Create your account in less than a minutes,
Forgot password? how can I recover my password now!
Enter right registered email to receive password!
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.
Typical Form or Reparative Regeneration - Heteromorphosis Sometimes the part which grows back is not the same as that which was lost. The phenomenon is called Heteromorphosis.
Influence of Associated Ions The second important factor influencing the plant uptake of a given cation is the effects of the ions held in association with it. For instance, as
characters
What are Taxonomic characters Taxonomic characters Classification is done on the basis of information we have. More information gives better classification. Modern taxonomy
Which of the following is true for a toe corticospinal interneuron that produces action potentials during voluntary movements of the big toe of the right foot? A. Its dendrites
Setting priorities for action: It is not enough for our actions to be coordinated with events in the outside world; they must reflect our internal needs. Pain can flood conscious
What are the antigen-presenting cells of the immune system? The antigen-presenting cells of the immune system, also called as APC cells, are cells that do phagocytosis and dige
Define characteristics of prebiotics? Characteristics of prebiotics Are non-digestible dietary/food ingredients Are not hydrolyzed/absorbed in the upper GIT, reach
PLASMODESMATA Termed by Tangl & Strasburger. Cytoplasmic / Protoplasmic bridges between 2 adjacent cells. Desmotubules connects the E.R. of 2 cells. Plasmodesmata p
What are fossils? The Fossils are petrified vestiges of beings that lived in the past conserved by chemical and geological processes and found within rocks and sedimentary stra
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!
whatsapp: +91-977-207-8620
Phone: +91-977-207-8620
Email: [email protected]
All rights reserved! Copyrights ©2019-2020 ExpertsMind IT Educational Pvt Ltd