Kushwaha , R and Pandey, S and Chanda, S and Bhattacharya, Amita and Ahuja, Paramvir Singh (2008) Temperature-dependent growth and emergence of functional leaves: an adaptive mechanism in the seedlings of the western Himalayan plant Podophyllum hexandrum. Journal of Plant Research, 121 (3). pp. 299-309.

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Abstract

As an adaptive mechanism, hypocotyl dormancy delays emergence of functional leaf until favorable season of growth in Podophyllum hexandrum, an endangered medicinal plant of the western Himalayas. However, upon exposure of the freshly germinated seedlings to favorable temperature (25 dehree C), functional leaves emerged within 20 days. Therefore, we examined regulation mechanisms of growth and development of this alpine plant by temperature under laboratory conditions. The seedlings were exposed to (1) 25 degree C (temperature prevailing at the time of maximum vegetative growth), (2) 4 degree C (mean temperature at the onset of winter in its natural habitat), and (3) 10 degree C (an intermediate temperature). Slackened growth at 4 degree C was followed by senescence of aerial parts and quiescence of roots and predetermined leaf primordia. Rapid development of leaf primordia at 25 degree C was associated with increased starch hydrolysis. This was evident from higher a-amylase activity and reducing s 4 degree C. In contrast, the roots (perennating organs) showed a slight increase (1.36-fold) in a-amylase activity. Growth and development in seedlings growing at 10 degree C (temperature less adverse than 4 degree C) were comparatively faster. The content of reducing sugars and a-amylase activity were also higher in all the seedling parts at 1 degree C as compared to 4 degree C. This indicated larger requirements for sugar by the seedlings at 10 degree C. Irrespective of temperature, maximum changes in nitrate and nitrate reductase occurred during the initial 10 days, i.e., when the readily available form of sugars (reducing sugar) was highest. This indicated that a temperature-dependent availability of carbon, but not temperature itself, was an important regulator of uptake and reduction of nitrogen.

Item Type:	Article
Uncontrolled Keywords:	Adaptive mechanism. Biochemical parameters. Western Himalayas. Leaf emergence. Podophyllum hexandrum. Temperature
Subjects:	Plant sciences Plant Biotechnology
Divisions:	UNSPECIFIED
Depositing User:	Dr. Aparna Maitra Pati
Date Deposited:	29 Dec 2011 15:47
Last Modified:	29 Dec 2011 15:47
URI:	http://ihbt.csircentral.net/id/eprint/499

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