Photosynthesis and enzyme activities regulating starch biosynthesis in different varieties of sweet potato (Ipomoea batatas Lam.)
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Date
2016
Authors
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Department of Plant Biotechnology, College of Agriculture, Vellayani
Abstract
The present study entitled “Photosynthesis and Enzyme activities
regulating
starch
biosynthesis
in
different
varieties
of
Sweet
potato
(Ipomoeabatatas Lam.)” was conducted at ICAR-CTCRI, Trivandrum during the
period 2015-2016. The objective of the work was to the study the relation between
photosynthesis, leaf area and enzyme activities involved in regulating starch
biosynthesis in different genotypes of sweet potato and to identify the limiting
factor(s) in low starch varieties of Sweet potato.
The rate of photosynthesis, morphological and biochemical parameters
and enzymes activities involved in the starch biosynthesis were recorded at
monthly intervals in selected varieties. Morphological parameters such as total
number of leaves per plant, leaf area and tuber yield per plant were recorded
during 1 to 4 MAP. Rate of photosynthesis was measured using IRGA (infra-red
gas analyzer). The leaf area and photosynthetic rate were directly increasing the
productivity which was found to be higher in the Sree Arun and Kanhangad
variety. Biochemical parameters such as sucrose and starch content were
estimated in leaves and tubers of sweet potato varieties. The sucrose content was
relatively higher in leaves of Kanhangad variety and in tubers of ST-13 variety.
Starch content was higher in the variety Sree Arun which had a direct relation
with the photosynthetic rate and tuber yield. Activities of enzymes such as
AGPase, starch synthase (SS), sucrose phosphate synthase (SPS), sucrose
synthase (SuSy) and invertase were measured in both the leaves and tubers of
sweet potato. AGPase and SS were directly involved in the tuberization
throughout the development which was observed in Sree Arun variety. SPS was
highly active in leaves than tubers. SuSy and invertase are mainly involved in the
sucrose metabolism in leaves and highly active during the day time. The increased
activity of AGPase and SS in sweet potato tubers will open a new strategy for
bioengineering the efficiency of enzymes to improve the starch content in low
yielding sweet potato varieties. A detailed molecular study on enzymes involved
in starch biosynthesis will be necessary for increasing or improving the starch
content in tuber crops.
Description
PG
Keywords
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