Genetics of nitrogen-fixation, Biology

Assignment Help:

Genetics of Nitrogen-fixation

The genetics of nitrogen-fixation is known in detail in Klebsiella pneumoniae. There are twenty genes required in organising the complete N2-fixing apparatus. Interestingly, it has been shown that if all the twenty genes of Klebsiella are transferred to E coli, a non-N2-fixer, the latter becomes a N2-fixer. Some nif genes code for the structural components of nitrogenase while two genes (nif L and nif A) are regulatory. The fast growing Rhizobia like R. leguminosarum are knouin to contain three kinds of genes for N2-fixation. They are

  1. nif-genes required for the formation of functional nitrogenase as in Klebsiella,
  2. Nod-genes required for the formation of nodules in root and
  3. Fix-genes required for the maintenance of N2-fixation by the nodule.

They control oxygen protection of nitrogenase as well as ATP and reductant supply. There are about 18 nod-genes known which are activated by the inducer - flavonoid (leutolin) present in the exudate of roots. They are supposed to be involved in controlling various stages of Rhizobium infection leading to the formation of nodule. The nif, the nod and the fix genes are located on a plasmid in the fast growing rhizobia and on the chromosome in slow growing rhizobia. Nod-genes are known to control the host-range of the bacterium and it should be genetically possible to increase its host range, thus enabling it to infect cereals and produce root nodules on them. Recently cultured tissues of rice and wheat have been successfully infected with Rhizobium although the association does not have the capability of fixing nitrogen. This achievement, however, is a step closer to Rhimbium-wheat or Rhizobium-rice N2-fixing system.


Related Discussions:- Genetics of nitrogen-fixation

Consciousness as inner state, Q. Explain Consciousness as inner state? ...

Q. Explain Consciousness as inner state? Consciousness as inner state: We are conscious of thoughts, images, emotions and memories within ourselves though they may not have phy

Write down all the four quantum numbers of the electron, Write down all the...

Write down all the four quantum numbers of the electron in the outermost shell of rubidium (At. no.= 37) atom. a) What type of hybridization is associated with N in NH 3 ? b

Function of lipids, FUNCTIO N OF LIPIDS Fats are storage products ...

FUNCTIO N OF LIPIDS Fats are storage products of both plants and animals. I n plants , fats are commonly stored in spores and seeds while in animals they are sto

Explain the conjunctival impression cytology (cic), Explain the Conjunctiva...

Explain the Conjunctival impression Cytology (CIC)? Conjunctival impression cytology (CIC) is a simple, rapid and inexpensive method which is suitable for a field survey. By to

Harmons, which was the first harmone discovered#

which was the first harmone discovered#

What is the importance of iron in diet, Q. What is the importance of iron i...

Q. What is the importance of iron in diet? What is the disease caused by iron deficiency? Iron acts as a constituent of the hemoglobin molecule and of enzymes of the energetic

Define nutritional support management for pancreatic cancer, Define Nutriti...

Define Nutritional Support Management for pancreatic cancer? When there is deficiency of exocrine pancreatic secretions, adequate amounts of pancreatic extract are helpful. It

Examples on some plants species, examples on woody perennial Angiosperm spe...

examples on woody perennial Angiosperm species and herbaceous annual angiosperm species. thanks

Pollutions, what is detergent pollution and it''s effects and causes

what is detergent pollution and it''s effects and causes

Explain the indole production test, Explain the Indole Production Test? ...

Explain the Indole Production Test? Many microorganisms produce an enzyme tryptophanase which oxidizes amino acid tryptophan to produce pyruvic acid, indole and ammonia. We can

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