NK

Nafees Khan

Aligarh Muslim University

ORCID iD 0000-0001-7957-5832
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About

The research group of Prof. Nafees A. Khan has immensely contributed to abiotic tolerance mechanisms vis-à-vis a positive shift in the source-sink relationship. A modulation in the ascorbate-glutathione system was suggested in plants as a result of the induction of signal transduction by ethylene and its coordination with other phytohormones, abscisic acid, gibberellic acid, nitric oxide, jasmonic acid and salicylic acid, and nitrogen (N) and sulfur (S) enrichment. The N and S provide essential constituents of cysteine and the reduced-glutathione. This cross-talk between nutrients and phytohormones facilitates root and shoot growth, improves the source-sink relationship, and augments productivity under a constraint environment of salinity, drought, temperature, and metals toxicity. It has been postulated that crop plants achieve augmented use-efficiency of nitrogen and sulfur, optimizing the synthesis of ethylene, which regulated non-enzymatic antioxidant efficiency of ascorbate-glutathione system and biosynthesis of other hormones that confer abiotic stress tolerance and improve the photosynthetic potential of crop plants. These path-breaking R & D contributions in physio-biochemistry of abiotic stress tolerance strategies earned publications in high impact factor journals. Prof. Khan was declared as the Highly Cited Researcher-consecutively four times from 2019 to 2022 (Web of science. He has edited nineteen books and served as Editor/Guest Editor of the leading publishing platforms. He is elected Fellow of National Academy of Sciences, India (NASI), The Linnean Society, Indian Society for Plant Physiology and IBS.
Some highlights of our significant contributions are given below:
• Ethylene regulation of photosynthesis: We have shown that ethylene has a significant role in the regulation of photosynthesis via control of stomatal conductance or down-regulation of the Calvin cycle enzymes. It increases the use-efficiency of N and S, and thus have an influence on stomatal limitation and content and activity of ribulose-1,5-bisphosphate carboxylase/oxygenase (Rubisco). Ethylene increases photosynthesis via the availability of intercellular CO2 concentration and an increase in stomatal conductance. Ethylene-regulated photosynthesis was through an increase in carboxylation efficiency and an increase in stomatal conductance and the availability of intercellular CO2 concentration, thereby uncoupling the usual effects of increased CO2 to reduce stomatal conductance. Further, there was an interaction between ethylene and other hormones such as ABA and nitric oxide in guard cells that increases stomatal and photosynthetic responses.
• Abiotic stress tolerance is interplay of ethylene and nutrients: Ethylene increases use-efficiency of N and S and up-regulates the synthesis of reduced glutathione (GSH) and shows an increase in tolerance to abiotic stress factors, salinity, metals and temperature. Our studies establish that phytohormones increase the growth of above-ground parts of plants, leaf area index, and demand for higher nutrients utilization to meet the requirements of the growing canopy. Ethylene and other phytohormones show cross-talk with nutrients to influence growth, photosynthesis and source-sink relations under optimal or limited environmental conditions. Our investigations establish that GA confers ethylene mediated enhancement of nitrogen and sulfur-use efficiency, thereby promoting photosynthesis and plant growth.
• Investigations on others plant growth regulators (salicylic acid, jasmonic acid and nitric oxide) on crop development under abiotic stress: Application of these growth regulators modulate defense mechanisms and protects the integrity of photosynthetic apparatus, enhancing photosynthesis and restoring crop productivity under abiotic stress conditions. Manipulation of these phytohormone levels by exogenous application contributes to the adjustment of plant metabolism and development to various abiotic stress factors such as salinity, temperature and metals. Under the control of these exogenously applied phytohormones, there was a favourable shift in osmolytes biosynthesis, nutrients and ROS homeostasis and activation of the antioxidant system to counter the adverse effects of ROS generated by abiotic stress factors. Also, one phytohormone influences the biosynthesis of the other hormone and exhibits cross-talk with plant responses to abiotic stress.
• Ethylene-Defoliation of shaded leaves and modulation of source-sink relations: The removal of mature shaded leaves allocates more photosynthates to growing/de novo differentiating crop organs, thereby improving use-efficiency of mineral nutrients and augmenting crop performance under the control of ethylene. The removal of lower matured leaves, which began acting as a sink instead of source allows an increase in the photosynthetic potential of younger growing leaves. The phenomenon is regulated by the hormone ethylene.

Employment

  • Aligarh Muslim University Professor
    2006 - Present
  • Aligarh Muslim University Associate Professor
    1999 - 2006
  • Aligarh Muslim University Assistant Professor
    1990 - 1999
  • Aligarh Muslim University Research Associate
    1989 - 1990

Education

  • Aligarh Muslim University D.Sc.
    2006 - Present
  • Aligarh Muslim University Ph.D.
    1984 - 1988
  • Aligarh Muslim University M.Sc.
    1981 - 1983
  • Aligarh Muslim University B.Sc. (Hons.)
    1981 - 1983

Projects & Funding

Projects & funding information is unavailable.

Publications (236)