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

Disorders of gonads, DISORDER S OF THE GONADS Hypogonadism. Inadequa...

DISORDER S OF THE GONADS Hypogonadism. Inadequate gonadal function is called hypogonadism. It is due to defects in, or injury to the hypothalamus, the pituitary gland, of th

What is an example of intraspecific competition, Q. What is an example of i...

Q. What is an example of intraspecific competition? The Intraspecific competition occurs in practically all species, for instance, the competition of humans for a job.

Nitrogen fixation and assimilation, Nitrogen is needed mostly for the synth...

Nitrogen is needed mostly for the synthesis of amino acids and nucleotides. Sources of nitrogen can be obtain from organic as well as inorganic sources, but the whole target is the

Human respiratory system - bronchioles, BRONCHUS - In thorax trachea is...

BRONCHUS - In thorax trachea is devided in to 2 bronchi that enter into lungs of its own side. Rings present in it. BRONCHIOLES - These are branches of bronchus.

The child''s response to hospitalization, The Child's Response to Hospitali...

The Child's Response to Hospitalization   The  factors influencing the response of  the child to hospitalization are the child's age, his personality, the preparation he receiv

Role of protein in metabolism, ROL E OF PROTEIN - Main organic comp...

ROL E OF PROTEIN - Main organic component of body. Unit is amino acid. Polymer of amino acids. Amino acids combine to each other by peptide bond. Formation of bone, t

Vitamins requirement in dyslipidemia, Q. Vitamins requirement in dyslipidem...

Q. Vitamins requirement in dyslipidemia? Antioxidants and flavonoids, natural vitamin E, vitamins C and Aare nutrients (vitamins) that scavenge cell-damaging free radicals and

Bacterial diseases-pigs, Pigs This is a sub-acute or chronic infection ...

Pigs This is a sub-acute or chronic infection manifested by abortion, sterility, high piglet mortality and orchitis in pigs. Br. suis causes brucellosis among pigs. It is morph

Methods to overcome incompatibility, Methods to Overcome Incompatibility ...

Methods to Overcome Incompatibility It has been possible to facilitate the germination of incompatible pollen by extracting pollen wall proteins from compatible pollen and su

Homologous proteins - amino acid sequence in fasta format, Please answer th...

Please answer the following question on Sequence Y: Protein databases 1. What sequence from which organism is this sequence most similar to? 2. Can you find any homo

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