Suspensor - pollen biology, Biology

Assignment Help:

Suspensor - Pollen Biology

The structure and function of suspensor have not been given adequate attention. During the last decade, however, investigations have produced noteworthy results. These include ultra structural, isoenzymatic, physiological, and in vitro experiments. A great deal of variation occurs in suspensor structure, probably modified to support the developing embryo. During 1950's and 1960's embryologists believed that it the suspensor is merely a morphological organ that pushes the embryo deeper into the more friendly environs of endosperm. This view is gaining reconsideration. The suspensor plays a more dynamic role than was hitherto assigned. The special kind of plastids present in legumes such as Pisum and Phaseolus and in Ipomoea and Tropaeolum show remarkable ultra structural changes around late heart-shaped stage of embryo.

The significance of these unusual plastids needs to be determined. Another feature of interest is the presence of wall embayments lined by plasma membrane in the suspensor cells supposed to be involved in short distance translocation of metabolites similar to transfer cells. Some experiments demonstrate the significance of presence of suspensor for proper development of the embryo. During early stages, removal of suspensor reduces embryo development but, at later stages, it has no effect. However, it is possible to replace, at least partially, the effect of suspensor loss by providing gibberellins in the culture medium. The finding is further substantiated by quantitative analysis of GA present in the suspensor and embryo proper cells. This GA has been identified as gibberellin Al. The relative concentrations of auxin in embryo proper and suspensor of Tropaeolum majus have been studied through single ion detection. The suspensor proper yields significantly higher concentrations of auxin. Likewise, in Phaseolus, the suspensor of heart-shaped embryo shows more cytokinin. However, at mid- cotyledonary stage, suspensor contains low cytokinin and the embryo seems to become autonomous for cytokinin.


Related Discussions:- Suspensor - pollen biology

Introduction to avian infectious diseases, Poultry birds are affected with ...

Poultry birds are affected with many types of ailments; broadly these are classified on the basis of etiology as non-infectious and infectious conditions. Non-infectious diseases a

Explain the meaning of life style modification, Explain the Meaning of Life...

Explain the Meaning of Life Style Modification Life Style Modification (LSM) is an important aspect in the treatment of diabetes. LSM will help the people who are pre-diabetic

Bacterial diseases-sheep and goats, Sheep and goats The disease is rea...

Sheep and goats The disease is readily transmissible to human being from goats, and is known as Malta fever, Mediterranean fever or undulant fever. The chief causal agent is B

Explain lateral meristem, Which one of the following is not a lateral meris...

Which one of the following is not a lateral meristem? 1. Intrafascicular cambium 2. Interfascicular cambium 3. Phellogen 4. Intercalary meristem   Intercalary m

Consequences on the bony structures, Q. Consequences on the bony structures...

Q. Consequences on the bony structures? Basal bone forms the dental skeletal structure. Wolff's law states that the bone remodels in relationship to the forces applied. With a

How many are the pulmonary veins, Q. What and how many are the pulmonary ve...

Q. What and how many are the pulmonary veins? The pulmonary veins are part of the pulmonary circulation they are vessels that carry oxygen-rich (arterial) blood from the lungs

Explain low birth weight infants (lbw), Explain Low birth weight infants (L...

Explain Low birth weight infants (LBW)? One-third of the babies born in US are of low birth weight, less than 2.5 kg. A LBW infant has an inadequate mineralized skeleton, poorl

Electron transport inhibitors, Electron Transport Inhibitors Several  c...

Electron Transport Inhibitors Several  compounds, including specific drugs, chemicals  and antibiotics  have been known to inhibit the electron  transfer  reactions at specific

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