INDUCTION OF EMBRYOGENY AND PLANT REGENERATION THROUGH INDUCED ANDROGENESIS/GYNOGENESIS IN MARIGOLD (Tagetes spp. L.)
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Date
2018
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Division of Floriculture and Medicinal Crops ICAR-Indian Institute of Horticultural Research, Hesaraghatta Lake Post, Bengaluru
Abstract
The present investigation “Induction of embryogeny and plant regeneration through
induced androgenesis/gynogenesis in marigold (Tagetes spp. L.)” was carried out in the
Division of Floriculture and Medicinal Crops, ICAR-IIHR, Bengaluru. Marigold, an
important ornamental plant is also recognised as a potential source of carotenoids used
as nutritional supplements and poultry feed. Improvement of this valuable species is
hampered by its heterozygosity. Production of doubled haploid is one of the most
efficient and time-saving innovative technology in varietal improvement. The present
study was undertaken to investigate the potential of anther or microspores culture of
marigold cv. ‘Pusa Narangi Gainda’ and unfertilized ovary or pseudo-fertilized ovule
culture of marigold cv. ‘Arka Agni’ for the production of haploid plants.
In case of anther culture, anthers containing microspores at uninucleate stage
(pre-treated at 4°C for 72 hrs) cultured on MS media supplemented with 3% sucrose +
4.44 µM 6-benzylaminopurine (BAP) + 1.07 µM α – naphthalene acetic acid (NAA) +
0.8 % agar and incubated in dark for 3 weeks at 25°C resulted in highest callus induction
(97.00 %). While isolated uni-unicleate microspores (pre-treated at 4°C for 72 hrs)
cultured on MS media supplemented with 14% sucrose + 4.44 µM BAP + 1.07 µM
NAA and incubated in dark for 4 weeks at 25°C resulted in highest number of calli
induction per Petri plate (17.60). However, obtained calli failed to differentiate further
into shoots on exposure to 16 hrs photoperiod. In addition, unfertilized ovaries cultured
from flower buds pre-treated at 45°C for 3 hrs on MS media supplemented with 4%
sucrose + 4.44 µM BAP + 4.52 µM 2, 4-D and incubated in dark for 4 weeks at 25 °C
resulted in highest callus induction (99.66%). Furthermore, in pseudo-fertilized ovule
culture, marigold cv. ‘Arka Agni’ flowers was pollinated with 200 Gy gamma irradiated
pollens. It was found that ovules cultured from pre-treated (at 4 °C for 24 hrs) flower
capitula on MS media supplemented with 4% sucrose + 4.44 µM BAP + 2.68 µM NAA
and incubated in dark for 4 weeks at 25°C showed highest per cent callus induction
(62.00 %) as well as highest embryo germination (8.07 %). Besides, shoot
differentiation was highest (96.33, 23.66, 25.33 %) from anther, unfertilized ovary and
pseudo-fertilized ovule calli, respectively when calli were sub cultured on MS media
supplemented with 3% sucrose + 4.44 µM BAP + 1.07 µM NAA and placed under 16
hr photoperiod at 25°C. Nonetheless, shoots derived from the above protocols rooted
readily on hormone free MS media. Subsequently, among the fifty plants selected
randomly, cytological analysis identified; 3 haploid, 3 triploid, 1 mixoploid and 43
diploid from anther derived plantlets, 3 triploid, 3 mixoploid and 44 diploid from
unfertilized ovary plantlets and 2 haploid, 2 triploid, 1 mixoploid and 45 diploid from
pseudo-fertilized ovule plantlets. Henceforth, the present study builds useful foundation
for further research towards the development of homozygous Tagetes erecta or other
Tagetes species
Description
t-9873
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