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

Distribution of stomata, Distribution of Stomata There are two paramet...

Distribution of Stomata There are two parameters normally used for expressing the distribution of stomata. Stomatal frequency: The number of stomata per unit area

Races of modern man, RACE S OF MODERN MAN Australoids Negroids ...

RACE S OF MODERN MAN Australoids Negroids Caucasoids Monogoloids American Indian Polynesian All human races have the same number of chromosomes (46) and b

Define about the gastric cancer, Define about the Gastric Cancer? Surgi...

Define about the Gastric Cancer? Surgical treatment is a very common mode of treatment in gastric cancer. Radiation and/or chemotherapy are given for patients with resected but

Planeria, differnce between protonephridia and metanephridia

differnce between protonephridia and metanephridia

Determine the genotypes and phenotypes, Determine the genotypes and phenoty...

Determine the genotypes and phenotypes of the F1 generaiton from a colour blind father and a mother who is homozygous for normal colour vision

Define pasteurization and sterilization - thermal processing, Define Pasteu...

Define Pasteurization and Sterilization - thermal processing? Pasteurization: Pasteurization is a mild heat treatment to kill part of the microorganisms present in food

Wetlands - lentic ecosystems, Wetlands - Lentic Ecosystems Wetlands a...

Wetlands - Lentic Ecosystems Wetlands are permanently or periodically water covered areas. They can be defined as submerged or saturated lands either artificially or naturall

CLASSIFICATION, WHY CORALS MAY SOMETIME BE CONFUSED WITH PLANT

WHY CORALS MAY SOMETIME BE CONFUSED WITH PLANT

Respiratry system, prepare a power point presantation of respiratry system

prepare a power point presantation of respiratry system

Defina about the lipid metabolism, Defina about the Lipid Metabolism? A...

Defina about the Lipid Metabolism? Animal studies consistently show a hypotriglyceridenlic effect although equivocal results have been seen with healthy humans. Hypotriglycerid

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