IN VIVO MUTAGENESIS IN APPLE (Malus × domestica Borkh.)
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Date
2024-06-13
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UHF Nauni
Abstract
The present investigation entitled “in vivo mutagenesis in apple (Malus × domestica Borkh.)” was
carried out at the Experimental Farm, Department of Fruit Science, Dr YS Parmar University of Horticulture and
Forestry, Nauni, Solan, Himachal Pradesh during 2021-2023. The experimental material was comprised of scion
budsticks irradiated with different doses of gamma rays of two apple varieties namely Scarlet Spur II and Early Red
One. The scion budsticks of both the varieties were irradiated with gamma rays (2.0 kR, 3.5 kR, 5.0 kR and 6.5 kR)
and grafted onto M9 rootstock for raising M1V1 generation in the year 2022. The desired variants selected from
M1V1 were grafted further onto M9 rootstock to raise M1V2 generation in the year 2023. The saplings of M1V1
generation not exhibiting any morphological variation were subjected to re-irradiation with the same respective
doses as given in the previous year for raising M2V1 generation in the year 2023. The probit analysis for gamma rays
indicated that the LD50 value based on survival per cent over control was determined as 4.62 kR and 4.65 kR,
respectively in M1V1 generation and 4.66 kR and 4.54 kR, respectively in M2V1 generation for Scarlet Spur II and
Early Red One. The observations were recorded on survival percentage, lethality percentage, plant vigor, plant type,
plant habit, sapling diameter, length of internode, shoot colour, shoot pubescence, leaf blade attitude in relation to
shoot, length of leaf blade, width of leaf blade, leaf blade ratio, intensity of green colour of leaf blade, leaf blade
pubescence on lower side, leaf blade incisions of margins, petiole length, number of leaves, leaf area, leaf apex
shape, leaf base shape, colour of young leaf, chlorophyll content, fresh weight of leaf, dry weight of leaf, mutation
frequency and mutation effectiveness. The molecular analysis of the identified variants was carried out using CBDP
and SCoT markers. Experimental results revealed that single dose irradiation of gamma rays has significantly
influenced the plant vigor, length of internode, shoot colour, leaf dimensions, number of leaves, leaf area, petiole
length, chlorophyll content, fresh weight and dry weight of leaves and mutation frequency. The repeated irradiation
of gamma rays has also significantly affected all these characteristics. On the basis of DUS guidelines, 27 potential
variants were identified in Scarlet Spur II and Early Red One varieties from M1V1, M1V2 and M2V1 generation and
molecular analysis of these identified variants revealed that eight variants were genetically different from control
plants.