TY  - BOOK
AU  - Revathi, B S
AU  - Beena Thomas (Guide)
TI  - Induction of heteroploidy in Dendrobium sp. 
U1  - 630.28 
PY  - 2021///
CY  - Vellayani
PB  - Department of Plant Breeding and Genetics, College of Agriculture 
KW  - Plant Breeding and Genetics
KW  - Heteroploidy
KW  - Dendrobium sp
N1  - M Sc
N2  - The present study entitled “Induction of heteroploidy in Dendrobium
sp.” was carried out at the Department of Plant Breeding and Genetics, College 
of Agriculture, Vellayani during 2019-21. The study was undertaken to induce 
heteroploidy in Dendrobium crumenatum using antimitotic agent colchicine 
via in vitro and in vivo technique.
In in vitro induction of heteroploidy in Dendrobium crumenatum, the 
explant used in the micropropagation was stem nodal segments containing one 
axillary bud and the basal medium chosen was VW medium. The best 
combination of surface sterilization agents identified were, 20 per cent sodium 
hypochlorite for 20 minutes followed by 0.1 per cent mercuric chloride for 5 
minutes and 70 % alcohol for 2 minutes. The medium VW+1 mgL-1 BA + 0.5 
mgL-1 2,4-D was chosen for callus induction, callus proliferation and PLB 
formation. The explants were maintained in dark for callus induction and 
proliferation and for subsequent stages a photoperiod of 16 hours light and 
eight hours dark was provided. For the induction of heteroploidy, PLBs were 
subjected to eight different colchicine treatments in basal VW suspension 
medium. Colchicine treatments were based on the concentration of colchicine 
(0.05%, 0.10%, 0.15%, 0.20%) and duration of exposure of PLBs to colchicine 
(24 and 48 hrs). For shoot induction, VW basal medium supplemented with 
the hormones BA (1mgL-1) and NAA (0.1 mgL-1) was used. The maximum 
survival percentage of cultures at shoot multiplication stage after different 
colchicine treatments was observed to be 83.33 per cent, and the minimum 
survival percentage noted was 25 per cent.
In in vivo induction of heteroploidy in Dendrobium crumenatum, D. 
crumenatum plantlets were subjected to eight different colchicine treatments, 
based on colchicine concentration (0.05%, 0.1%) and the duration of exposure 
of plantlets to these doses of colchicine (24 hrs, 48 hrs, 72 hrs, 96 hrs). The 
highest percentage of plants showing response after colchicine treatment was 
found to be 83.33 per cent (observation recorded after 2 weeks of colchicine 
treatment) and the lowest percentage recorded was 16.67 per cent.
The observations shoot length, diameter of pseudobulb, number of 
leaves and width of leaves showed mean values greater than their 
corresponding control means, whereas the observations, diameter of shoot and 
length of leaf noted lower mean values than corresponding control. The mean 
value for the character height of pseudobulb were found to be same for treated 
and control plantlets. The character, number of leaves recorded high PCV and 
GCV. Moderate PCV and GCV were recorded for the characters viz., diameter 
of pseudobulb, length of shoot, length of leaf and width of leaf. The characters, 
diameter of shoot and length of pseudobulb obtained low PCV and GCV. 
Significant positive genotypic correlation was observed between length of 
shoot and height of pseudobulb, diameter of shoot and width of leaf, length of 
pseudobulb and number of leaves, number of leaves and length of leaf and 
width of leaf and number of leaves.
Flow cytometry analysis of the colchicine treated in vivo and in vitro
D. crumenatum samples were performed at Rajiv Gandhi Institute for 
Biotechnology, Poojapura. The histogram peaks obtained after the analysis of 
control (diploid) and treated samples were compared for interpretation of the 
results. In the in vitro treated samples, the maximum tetraploids (66.67 %) 
were obtained from treatments 0.15% colchicine, 24 hrs and 0.10 % colchicine, 
48 hrs. On analyzing the histogram peaks of in vivo treated samples, the highest 
tetraploid induction (50%) was noticed in treatment 0.05% colchicine, 96 hrs. 
It was concluded from the present investigation that, for Dendrobium 
crumenatum which was subjected to both in vitro and in vivo colchicine 
treatments, in vitro colchicine treatment was found effective than in vivo
colchicine treatment, when the concentration and duration of exposure to 
colchicine used for the study were same
ER  -