PROTEIN AND ISOZYME VARIATION AND ITS RELATION TO STRESS RESPONSE IN GROUNDNUT (Arachis hypogaea L.) GENOTYPES
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Date
2001-08-07
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UNIVERSITY OF AGRICULTURAL SCIENCES GKVK BANGALORE
Abstract
The potential of protein and isozyme polymoiphism for varietal identification and
to monitor abiotic stress resistance in Arachis hypogaea L., was explored in the present
investigation. Thirteen genotjpes, comprising eleven cuhivars and two potential genotypes
under adoptive trials and ten mutants encompassing foliar disease resistant mutants and
their susceptible counterparts were evaluated for protein and iso2yme polymorphism.
These genotypes were also subjected to various abiotic stresses and response in terms of
growth and protein and isozyme variation was studied.
Of four enzymes assayed, only Glutamate Oxaloacetate Transaminase was
polymorphic. It could differentiate uptp subspecies level only. For Peroxidase and Super
Oxide Dismutase only tissue specific variation was observed. However, protein profiles
were more variable. Seed, root and hypocotyl protein profiles had three, three and four
electrophoretic phenotypes, respectively. All the three protein profiles were used in
combination for varietal identification. This could uniquely identify seven out of thirteen
cultivars. The other three groups comprised of two cultivars each.
The genotypes were subjected to moisture stress using PEG. In case of
temperature and salt stress, induction studies were carried out Genotypes differences were
clearly seen under temperature stress but only limited variation was noticed under salt
stress. In cultivars, two protein bands (Rf value 0.19 and 0.23) were polymorphic under
moisture and temperature stressed conditions. They were present in resistant cultivars even
under stress but absent in susceptible cultivars.
In case of mutants, the resistant counter parts performed better under both moisture
and temperature stresses. The two polymorphic bands (Rf 0.19 and 0.23) were absent in
some mutants under moisture stress. Under temperature stress, only one band (0.19) was
absent. Two bands of Peroxidase (Rf value 0.628 and 0.686) were induced under stress.
These bands were constituthely Present in I 15 e, an interspecific derivative, which has
performed better under temperature stress. The precise identity of these protein bands and
regulation of Peroxidases need to be elucidated so that these could be used as potential
markers for abiotic stress tolerance.
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