Changes in the photosynthetic characteristics of Catharanthus roseus L. as a result of exogenous growth regulators by ProQuest


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									Plant Omics Journal                                                           Southern Cross Journals©2009
2(4):169-174 (2009)                                                         
ISSN: 1836-3644

 Changes in the photosynthetic characteristics of Catharanthus roseus L. as a result of
                             exogenous growth regulators
                 Cheruth Abdul Jaleel, 2Guixue Wang, 3Parvaiz Ahmad, 4Ikram-ul-Haq

          Stress Physiology Lab, Department of Botany, Annamalai University, Annamalainagar 608 002,
                                                  Tamilnadu, India
                 College of Biological Engineering, Chongqing University, Chongqing 400044, China
                    Plant Molecular Biology, ICGEB, Aruna Asaf Ali Marg, New Delhi 110067, India
    Institute of Biotechnology and Genetic Engineering (IBGE), University of Sindh, Jamshoro, Pakistan.

                             *Corresponding author:


In the present investigation, different plant growth regulators and retardants were used to analyse their effects on
photosynthetic characteristics of common periwinkle (Catharanthus roseus (L.) G. Don., Family:
Apocynaceae). The plant growth retardant used was paclobutrazol. The synthetic growth regulator used was
gibberellic acid. The exogenously applied non-traditional growth regulator was an elicitor named Pseudomonas
fluorescens. From the results of this investigation, it can be concluded that these growth retardant and regulators
altered the photosynthetic characteristics of C. roseus to a great extent. These findings might have a great role in
the ayurvedic or natural medicine, as more and more people became interested in traditional medicine, due to the
secondary hazardous effects of most of the modern synthetic medicines.

Keywords: periwinkle; photosynthesis; growth regulators; growth retardants.


The plant hormones are organic substances in low               vegetative    and reproductive           growth and
concentrations regulates        the    growth and              physiological activities of plant (Jaleel et al.,
development. These substances belongs to different             2007a). Phytohormones play a crucial role in the
classes have different physiological role in plants to         regulation and coordination of plant growth,
modify, regulate and development. The naturally                morphogenesis and metabolism. It is thus
occurring plant growth substances include auxins,              postulated that they also play a role in the
gibberellins, cytokinins, abscissic acid and ethylene          biosynthesis of alkaloids (Jaleel et al., 2007b).
(Kakimoto, 2003). The role of growth hormones in                  The plant hormones gibberellin (GA) and
regulation of indole alkaloids has been extensively            abscisic acid (ABA) exert profound effects on
studied (Moreno et al., 1995). The term plant                  fundamental processes of plant growth and
growth regulators are not only restricted to                   development (Jaleel et al., 2009). Moreover, recent
synthetic compounds but also include the naturally             advances in understanding GA and ABA signaling
occurring hormones (Werner et al., 2001). Hence,               point to the existence of multiple, non-linear cell
the plant growth regulator can be defined as either            and compartment-specific pathways that regulate
natural or synthetic compounds that modify the                 genomic and non-genomic responses to these
plant growth and development pattern exerting                  phytohormones. GA is widely regarded as a
profound influence on many physiological                       growth-promoting compound that positively
processes (Akazawa et al., 1990; Jaleel et al.,                regulates processes such as seed germination, stem
2006). Plant growth regulators are found to have               elongation, leaf expansion, pollen-tube growth,
many practical applications in controlling                     flower and fruit development and floral transition

(Swain and Singh, 2005). ABA, by comparison, has               
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