IN VITRO INDUCTION OF POLYPLOIDY IN GINGER (Zingiber officinale Rosc
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Date
2024-01-11
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UHF,NAUNI
Abstract
ABSTRACT
The present study reports the successful in vitro tetraploid induction in ginger (Zingiber officinale
Rosc.) cv. Himgiri using colchicine (0.1, 0.2, 0.3 and 0.4%) for different time durations (6, 12, 18, 24, 30, 36, 42
and 48 hrs). Maximum per cent bud survival (73.33%) was achieved with 0.1% colchicine treatment for 6 hrs
which decreased with the increase in colchicine concentration and treatment duration. Shoot multiplication rate
and average shoot length increased with the subculture and was maximum in shoots regenerated from buds
treated with 0.2% colchicine for 24 hrs. LT50 calculated after 16 weeks was 22.13, 15.26, 4.53 and 1.59 hrs for
colchicine treatment of 0.1, 0.2, 0.3 and 0.4%, respectively. The maximum induction of polyploidy (50%) was
achieved with 0.2% colchicine treatment for 6 and 24 hrs whereas, no polyploidy was induced with 0.4%
colchicine treatment. Flowcytometric analysis of regenerated shoots reported different ploidy levels (triploid,
tetraploid and hexaploid). These identified polyploids were multiplied through repeated subculturing for four
months and analyzed again for stability of ploidy level through flowcytometry. It was observed that the triploid
and hexaploid plants reverted back to diploid and tetraploid state whereas, the tetraploids remained stable. The
chromosome number of the tetraploids were again confirmed microscopically and was 44 in comparison to 22
observed in diploids. The confirmed tetraploids were multiplied in vitro for four months and the rooted plantlets
were hardened with 100% survival. Morphological parameter such as plant height (73.33 cm), leaf length (25.50
cm), leaf width (3.50 cm), leaf area (58.92 cm2) were maximum in tetraploids induced after 24hrs treatment with
0.2% colchicine whereas, maximum number of tillers (7.60) was observed in tetraploids induced after 30 hrs
treatment with 0.2% colchicine however, no significant difference in stem girth was observed in tetraploids and
control plants. The number of leaves per tiller was maximum (14.33) in control plants. All the physiological
parameters such as photosynthetic rate, stomatal conductance and transpiration rate were observed to be
maximum in tetraploids. On biochemical analysis the tetraploids induced from 0.1, 0.2 and 0.3% colchicine
treatment for 36, 24 and 30 hrs showed maximum chlorophyll a (6.25 μg/ml), chlorophyll b (4.40 μg/ml) and
total carotenoid content (1.38 μg/ml), respectively. Maximum oleoresin (4.81%) and low crude fibre (8.60%)
content was reported in rhizomes of tetraploids induced from 0.2% colchicine treatment after 30 hrs and tissue
culture propagated control plants. Whereas, maximum total protein (112.22 μg/ml) and sugar content (40.86
μg/ml) was observed in plants regenerated after 0.2% colchicine treatment for 30 hrs. HPLC analysis depicted
maximum gingerol content (498.36 μg/g) in harvested rhizomes of tetraploid induced with 0.2% colchicine
treatment for 24 hrs. On molecular analysis maximum polymorphism of 10.87% and 35.67% was depicted by
SCoT and CBDP respectively, showing alteration in the genome