CSIR Auxin Phytohormone Notes
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CSIR NET Life Science Auxin Phytohormone Notes

Today’s Do Not Skip CSIR NET Topic deals with another important topic of the CSIR NET Life science exam: Plant growth regulators (Auxin Phytohormone). Are you looking for some readymade CSIR NET Notes? Revise faster with these expert-designed mind maps for Plant growth regulators. Also, understand:

  • The importance of this topic – Plant growth regulators (Auxin Phytohormone) as per the CSIR NET Exam
  • What are the important concepts you must learn & revise from Plant growth regulators Topic
  • How many marks do questions usually come in the CSIR NET exam on this topic?
  • Types of questions asked
  • Reference Books
  • Download CSIR NET Plant AUXIN PHYTOHORMONE Fast Revision Notes / Mind Map 


Plants are exposed to a variety of abiotic stresses, such as high temperature, drought, salinity, and heavy metals, which have been shown to have a negative impact on the plant’s morphology and physiology through defects in the genetic elements of cellular responses. However, on the other hand, it also employs several pathways and mechanisms to escape these stresses when encountered by the plant’s defence mechanism. Plant growth regulators are among the most important signalling molecules that have a well-known effect on plants’ metabolism and play a leading role in the growth and development of plant species.

At present, these phytohormones are classified broadly into five categories on the basis of their derivatives: indoles (auxins), carotenoids (abscisic acid), terpenes (Gibberellins), gases (ethylene) and adenine (cytokinins). They are thought to be synthesised in one part of a plant and are transferred to different parts with the help of transporters and associated proteins. On a large scale, the functions that these regulators have over plant growth include phototropism, seed germination, vernalization, dormancy etc, along with other external factors.

In addition to growth-promoting substances, auxin belongs to a group of plant hormones that modulate growth, specifically by stimulating stem cell elongation. It is the first plant hormone to be discovered by Darwin (1880) as a growth chemical in the tip of a coleoptile, which also has a pronounced effect on fruit development, cell differentiation, root formation, and apical dominance. Indole-3-Acetic Acid (IAA), the naturally produced auxin, is synthesised from the amino acid tryptophan and is the most bioactive form with great value in research and horticulture.

CSIR Auxin Phytohormone Notes

Download CSIR NET Auxin Phytohormone Fast Revision Notes / Mind Map 

Important concepts to learn & revise from Plant Growth Regulators :

  • Detailed understanding regarding the signal transduction pathway utilised by auxin.
  • Comprehensive knowledge of growth-promoting molecule discovery, ligand, receptor, inhibitor, transcription factor, and cellular responses.
  • Focusing on the biosynthetic pathways concerned; location of the pathway, intermediates formed and the reactions involved.
  • Auxin’s functional profile as a phytohormone.
  • Transport mechanisms (and related inhibitors) and the proteins involved.

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Types of questions asked related to Plant Growth Regulators in CSIR NET Exam :

  • Direct questions regarding the most bioactive form of auxin, inhibitors involved in signalling and the enzymes regulating the signalling pathway
  • Statement and Combination-based questions about the signalling underlying cellular responses in plants
  • Match the following questions to pair phytohormones with their precursor molecules and their related functions
  • Questions related to transport and biosynthesis (organelles involved) can be expected. Also, the inhibitors coupled with the transport mechanisms, if any
  • Experimental-based questions about the combination of regulators (ex. auxin and cytokinin) and their interaction in regulating plant growth and development
  • Related questions with mutational phenotypes (mutation-based study) for receptors involved in signalling.

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Weightage of this topic – Plant Growth Regulators in the CSIR NET exam :

  • You can find questions on phytohormones in every competitive exam; say CSIR NET, GATE, DBT, ICMR, etc. In CSIR NET, this topic is asked for 8-10 marks every year (including part B and part C)
  • Auxin phytohormone and signalling mechanisms are likely to generate 1-2 questions.

Reference books for this topic :

  • Plant Physiology by Lincoln Taiz and Eduardo Zeiger
  • Plant Physiology by Ross and Salisbury
  • Introductory Plant biology by K.R. Stern

Download CSIR NET Plant AUXIN PHYTOHORMONE Fast Revision Notes / Mind Map 

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