| Plant Gene Expression |
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| DU - 5 |
DP - 2 |
| Group Leader |
Dr. Pravendra Nath, Sci
'F' |
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Contact |
Work
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91-522-
2205841 Ext 331, 332 |
| Home |
91-522- 2739323 |
| Email |
pravendranath@hotmail.com |
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| Other Scientists of the Group |
Dr. P. K. Trivedi, Scientist C
Dr. A. P. Sane, Scientist C
Dr. (Mrs.) V. A. Sane, Scientist C |
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| Group works on |
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| The laboratory of Plant gene Expression is engaged
in the development of post harvest biotechnology for fruit,
flower and vegetables for sustainable agriculture practices.
There has been many fold increase in the production of fruits,
vegetables and flowers in the last couple of decades. This could
be attributed mainly to good agriculture practices as well as
development of high yielding varieties. However, in cases of
perishable fruits and vegetables as also exotic cut flowers
the value destruction has also increased proportionately due
to lack of appropriate post harvest measures. We have initiated
recombinant DNA technology program in fruits, vegetable and
flowers to develop transgenic varieties, which show desired
post harvest behaviour and have higher shelf and vase life.
The crops selected are banana, mango, tomato, rose and gladiolus. |
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| Achievements |
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| Molecular biology of ripening in climacteric
fruits |
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| Banana and mango are major fruit crops for export
and there are certain exotic but delicate varieties, which do
not find place in export market as they perish quickly. We at
the Plant Gene expression lab. are making efforts to develop
such varieties through gene manipulations that have higher shelf
life. Genes for cell wall modifying enzymes such as PG, XET,
pectate lyase and expansins and genes for ethylene biosynthesis
and perception such as ACO, ACS and etr have been cloned and
characterized from both banana and mango. Transgenic tomato
plants expressing antisense ACO gene from banana show delayed
post harvest softening of ripe tomato. Using differential display
techniques and PCR select subtractive hybridisation several
novel up regulated and down regulated genes in banana have been
identified. Many of these genes show fruit specific and ripening
related expression. Functional analysis of these genes through
over expression and antisense expression is underway in tomato
and banana. We have also cloned at least three proximal promoters
from the genes specific to ripening in banana. These are being
characterized through transient expression analysis of promoter-GUS
fusion construct in order to realize if these promoters can
be utilized to express desired genes specifically in fruits.
Beside these ethylene responsive factors (ERFs) which are believed
to finally control activities of target genes during ripening
are being studied in tomatoes. Functional analysis of these
factors through transgenics may reveal underlying mechanism
of ripening in climacteric fruits. |
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| The molecular basis of petal abscission in
rose and senescence in gladiolus |
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| The vase life of flowers is of major consideration
in the cut flower industry. A short vase life is undesirable
and is mainly caused by two ethylene regulated processes viz.
abscission and senescence of petals. Our major aim is to understand
the molecular mechanism behind these processes and understand
role of ethylene in governing these. We have selected two important
cut flowers viz. rose and gladiolus, that respond differently
to ethylene, in order to study these processes. In rose, exposure
to ethylene results in rapid abscission of petals whereas gladiolus
undergoes a gradual senescence. Using mRNA differential display
we have identified several genes that are differentially expressed
during the formation of the abscission zone in petals in rose
and during the process of senescence in gladiolus. Homologues
of genes that are known to be involved in cell wall hydrolyses
and the ethylene signal pathway have also been identified in
rose abscission zones using a PCR based approach. The major
aim of these studies is also to identify promoters that drive
abscission / senescence specific expression and utilize these
promoters and genes to delay the onset of these processes by
an antisense or similar approach. |
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| Metabolic engineering of tomato plants for
biosynthesis of isoflavones |
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| Isoflavones form a group of distinct secondary
metabolites produced predominantly in leguminous plants. These
compounds have distinct role in plant defence and root nodulation.
The isoflavones, genistein and diadzein, which are naturally
occurring are presently being studied for their role in human
health. The reported health benefits include relief in menopausal
symptoms, reduction in osteoporosis, improvement in blood cholesterol
levels and lower risk of certain hormone related cancers and
coronary heart diseases. Isoflavones are synthesized in plants
from flavone, naringenin and liquiritigenin, by the cytochrome
P450 enzyme isoflavone synthase (IFS). IFS and Chalcone isomerase
(CHI) are entry point enzymes of isoflavone biosynthesis and
therefore the key step for engineering isoflavone production
into non-leguminous plants. Metabolic engineering for isoflavones
in crops that are not capable of synthesizing isoflavones would
provide food manufacturers an alternative to legumes (mostly
soy) for the use in their health products. Full-length cDNAs
of IFS and CHI genes have been cloned from soybean and attempts
to introduce these in tomato are underway. |
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