THE ROLE OF NEW GENERATION PHYTO HORMONES: AN OVERVIEW

 

ABOUT AUTHORS:
Lohithasu Duppala*, Santhosh naidu Matsa, Manikumar Kothakota,

GITAM Institute of Pharmacy, GITAM University, visakhapatnam, Andhra Pradesh, India-530045.

lohithasu@gmail.com, +91-9491894432

ABSTRACT:
Generally, almost all communication in higher plants was thought to be mediated by the five classes of classical plant hormones  i.e. auxins, cytokinins,  gibberellins, abscisic acid and ethylene. The plant hormone action thus appeared to be basically different from that in animals. This article discusses the general role for new generation of plant hormones includes Brassinosteriods, Salicylic acid. Peptides,Polyaminesand Jasmonates.

REFERENCE ID: PHARMATUTOR-ART-1687

INTRODUCTION:
Plant Hormones(Plant growth regulators):

These are small organic substances, which are synthesized in minute quantities by specific plant cells/tissues (one part of plant body) and transported to another part where  they influence specific physiologic processes(promote or inhibit growth and development), active in low concentration. Hormones are synthesized or stored in regions of transduction. Hormones travel within phloem or from cell to cell after reception of appropriate stimulus. The term HORMONE was first used by Starling in 1906s.

 Plant hormones-categories:

Based on function or chemical structure ,they can categorized into

1.Auxins- Natural (Indole -3-acetic acid) ;Synthetic (Indole -3-butyric acid, 2-methyl-4-chlorophenoxy acetic acid, Indole -3-propionicacid,2,4-dichlorophenoxy acetic acid)

2.Gibberllins-GA1 …..GAn in order of discovery

3.Cytokinins- kinetin, Zeatin, dihydrozeatin ,tricanthene, isopentenyl adenine etc.,

4.Growth inhibitors- Ethylene   ,Abscisic acid(stress hormone)  ,Chlorochine chloride,  Morphactins,  Maleic hydrazide

5.Other new generations- Brassinosteriods ,Salicylic acid,Peptides,Polyamines,Jasmonates and others.

  1. Brassinosteriods
  2. Salicylic acid
  3. Peptides
  4. Polyamines
  5. Jasmonates

1.Brassinosteriods :

Brassinolide structure

  • Chemically similar to animal steroid hormones.In contrast to animal steroid signal molecules,Brassinosteriods are perceived by a plasma memberane localized receptor kinase.These are the polyhydrxylated steroid hormones of plants. Studied in Arabidopsis.Brassinolide, is the most bio-active form from 70 naturally occurring Brassinosteriods.
  • Brassinolide was the first isolated brassinosteroid , when pollen from Brassica napus .The Brassinosteroids , biosynthesised from campesterol.  Brassinosteroids are recognized at the cell membrane, although they are membrane-soluble.1,2
  • Extract from the plant Lychnis viscaria contains a relatively high amount of Brassinosteroids. Lychnis viscaria increases the disease resistance of surrounding plants.
  • Brassinosteroids have been reported to counteract both abiotic and biotic stress in plants. Brassinosteroids increased tolerance to high temperature in Brassica juncea L.
  • These were first isolated from pollen of the mustard family and extensively.Over 70 naturally occurring Brassinosteriods are known.Effective at low concentrations.

Brassinosteriods stimulate3-12

  • Cell division ,stem elongation and cell elongation .
  • Cell wall loosening and cell wall regeneration.
  • Differentiation of xylem tissues and inhibit leaf abscission.
  • Plants found deficient in Brassinosteriods suffer from Dwarfism.
  • Regulate the growth and differentiation of plants throught their life cycle
  • Promotion of Vascular differentiation.
  • some protection to plants during chilling and drought stress.
  • Ethylene biosynthesis.
  • Required for fertility-Is necessary for pollen elongation for pollen tube formation.
  • Inhibit root development and growth.

2.Salicylic Acid:


 Salicylicacid   structure

· Salicylic acid, synthesized from phenylalanine. It is a monohydroxybenzoic acid, a type of phenolic acid and a beta hydroxy acid. It is found in plants with roles in plant growth and development, photosynthesis, transpiration, ion uptake and transport13.
· Promotes production of pathogenesis related proteins.
· Can reverse effects of ABA in some cases. SA also induces specific changes in leaf anatomy and chloroplast structure. SA is involved in endogenous signaling, mediating in plant defense against pathogens.

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