Int. J. Life. Sci. Scienti. Res., 4(2): 1675-1679, March 2018

Study of the Cytogenetical Effects on Meiotic Chromosomal Abnormalities Induced by Mutagens in Soybean

Geeta P. Patil¹*, C. T. Sharma²

¹Assistant Professor, Department of Botany, Arts, Commerce & Science College, Bodwad, Dist Jalgaon M.S. India

²Assistant Professor, Department of Zoology, Arts, Commerce & Science College, Bodwad, Dist Jalgaon M.S., India

^*Address for Correspondence: Dr. Geeta P. Patil, Assistant Professor, Department of Botany, Arts, Commerce & Science College, Bodwad, Dist Jalgaon M.S. India

ABSTRACT- An attempt was made to study the Cytogenetical effects of gamma rays and ethyl methane sulphonate on meiotic chromosomal abnormalities in two cultivars viz., PKV-1 and JS-335. The most frequently observed aberrations in meiosis were univalents, trivalent, multivalents chromosomal fragments, desynapsis of chromosome, laggards, and clumping of chromosomes etc. The physical mutagens were more effective than chemical mutagens. The effect of gamma-rays and ethyl methane sulphonate shows chlorophyll mutations such as Chlorina, Xantha, Albina and Alboviridis in an M₂ generation in both the cultivars. Cultivar JS-335 shows more pronounced effect than cultivar PKV-1. Gamma-rays recorded maximum macro mutations as compared to chemical mutagens (EMS). The frequency and spectrum of morphological mutation indicated that variety JS-335 was more sensitive than PKV-1. Different response of the two varieties to various mutagens was noticed.

Keywords: Gamma radiation, EMS, Chromosomal aberrations, Mutagens, Chlorophyll mutation      

 

INTRODUCTION- Soybean, Glycine max (L.) Merrill is one of the world’s most important sources of vegetable oil and protein. It is a highly self-pollinated crop, cultivated all over the world. Soybean being an autogamous crop, the naturally existing genetic variability may not be sufficient to achieve the desired improvement. Each kind of breeding method involves creation and utilization of genetic variability by means of hybridization, recombination and selection. Due to small size of flowers, emasculation and pollination in soybean is very tedious and costly. Alternatively artificially induced mutation is the best way to widen the genetic variability of a species considerably within a short time.

Mutation breeding is relatively a quicker method for improvement and creating genetic variability in crops. Attempts to induce mutations in soybean would be quite useful in creating genetic variability. Mutation is a sudden heritable change brought about in nucleotide base pairs either by addition, deletion or substitution ^[1]. It may be caused by the various factors which lead to a change in the coded information finally expressed in terms of a changed phenotype, through alteration in the chain of events like transcription and translation. In other words, the biochemical pathway gets affected resulting in the modified manifestation of a gene.

Recently, generation of genetic variability by induced mutagenesis provided a base for strengthening crop improvement programme and represents a more efficient source of genetic variability than the gene pool conservers by nature ^[2]. Hence, mutation breeding can be applied to altering specific characters in otherwise good varieties, by incorporating some useful changes such as earliness, high oil and protein content, high yields, non-shattering and disease and insect resistant in a comparatively shorter time than conventional breeding methods.

The choice of mutagens holds great importance in changing the spectrum of mutations in a predictable manner. Considering the above facts the present study intended to assess the effect of gamma rays, EMS (ethyl methane sulphonate) on induction of variability in two varieties of soybean.

MATERIALS & METHODS- Dry and healthy seeds of soybean variety JS-335 and PKV-1 were treated separately with chemical (EMS) and physical (gamma-rays) mutagens. 500 dry seeds of two cultivars were exposed to 15, 20, 25, 30, kR gamma-rays & also the same number were presoaked in distilled water for 6 hours & then flooded with freshly prepared 0.05%, 0.10%, and 0.15% aqueous solution of ethyl methane sulphonate for 6 hours. Then the treated seeds were thoroughly washed in running tap water. The treated seeds were immediately sown in the field with 45 x 10 cm spacing in two rows each treatment along with irradiated seeds and respective control to grow M1 generation. The sowing was done in Factorial randomized block design (FRBD) replicated thrice in the Field of Arts, Commerce and Science College in July 2012.

The seeds from each M1 plants were harvested separately and sown subsequently in progeny row basis in Rabi season (November 2012) to screen different chlorophyll and morphological mutations. Screening for chlorophyll mutations was done during the first 15 days of sowing of M₂ generation. Mutation types were identified following the classification of Gustaffson ^[3]. Twenty-five plants from each treatment were randomly selected from M2 population for raising M3 progeny in randomized block design with four replications during kharif season 2013. The observations were recorded on fifteen plants from each treatment per replication for almost all the characters studied in M₂ generation. The statistical analysis was carried out as per standard method of “Analysis of Variance” ^[4].  

RESULTS AND DISCUSSION- Data on frequency of morphological mutations observed in both soybean varieties viz. PKV-1 and JS-335 are presented in Table 1. The data revealed that the gamma-rays doses recorded maximum macro mutations as compared to EMS. However, the frequency and spectrum of morphological mutants indicated that cv. JS-335 was more sensitive than cv. PKV-1. As regards the mutation rate on the M₁ family basis it was found to be higher than the M₂ plant basis in both the varieties. Amongst mutagens, EMS in cv. PKV-1 and gamma-rays in JS-335 recorded highest mutation rate on M­₁ family and M₂ plant basis.

The frequency of macro mutations expressed on M₂ population basis as well as M₁ progeny basis was found increased as the dose of gamma-rays increased. The observations recorded are in agreement with those of Raut et al. ^[5] in Soybean, Narsinghani and Kumar ^[6]; Venkateswarlu et al. ^[7]; Venkateswarlu et al. ^[8] and Nandarajan and Ramalingani ^[9] in pigeon pea. Whereas, lower concentration in EMS, recorded the highest frequency in both the varieties. Study of spectrum of viable cultivars showed that numbers of viable mutations were induced for growth habit mutants followed by leaf mutants and then economic mutations.  The cultivar JS-335 produced relatively high number of macro mutations as compared to cv. PKV-1. In general, on an overall basis, it can be said that, irrespective of varieties, the physical mutagen i.e. gamma-rays was more effective than the EMS (Table 1).

Table 1: Frequency spectrum of macro mutations induced by different mutagens

 

Meiotic abnormalities- The various chromosomal aberrations recorded chromatin bridges, univalent, trivalent, quadrivalent, pentavalent, chromosomal fragments, desynapsis of chromosomes, laggards & clumping of chromosomes etc. the formation of trivalent & multivalent suggested that the exchange hypothesis may have operated in mutagen induced chromosome abnormalities as reported by Zeerak ^[10] in brinjal. The high chromosome stickiness may be due to reduction of correctly polymerized nucleic acid on the chromosome producing characteristic errors in spiralization which combined with superimposed excess of non polymerized nucleic acid causing surface stickiness ^[11]. High frequencies of chromosomal aberrations were recorded in gamma rays than by EMS indicating greater efficiency of gamma rays for inducing meiotic abnormalities (Table 2).

Table 2: Meiotic abnormalities as influenced by different mutagen

Mutagen	No of cells observed	Total cells with abnormalities	% abnormalities	Diakinesis				Metaphase I		Anaphase I		Telophase II
				Trivalent	Tetravalent	Multivalent	De-synapses	Trivalent	Tetravalent	Chromatin bridges	Laggards	Micronuclei
PKV 1
Control	250	2	0.8	-	-	-	(0.8)	-	-	-	-	-
γ rays	860	35	4.06	1.04	0.81	0.46	-	0.46	0.34	0.34	0.23	0.34
EMS	740	23	3.10	1.08	0.67	0.27		0.40	0.27	0.40	-	-
JS 335
Control	305	3	0.98
γ rays	915	48	5.24	1.31	0.98	0.54	-	0.43	0.32	0.54	0.65	0.43
EMS	872	32	3.66	0.80	1.03	0.22		0.34	0.34	0.45	0.22	0.22

 

Chlorophyll mutations and viable mutation- Four different kinds of chlorophyll mutant, viz. albina, xantha, chlorine, chlorine, and alboviridis were observed in both the cultivars. The data revealed that the different mutagens used differed significantly from each other for inducing chlorophyll mutations. However, gamma-rays in variety PKV-1 and ethyl-methane sulphonate in JS-335 was found most effective in inducing chlorophyll mutations so far as the different doses or concentration are concerned, all the doses were found effective in inducing chlorophyll mutations. Higher doses of gamma-rays showed maximum number of chlorophyll mutations in both the varieties viz. PKV-1 and JS-335.  Similarly, the higher concentration of EMS-induced maximum mutations in both the varieties PKV-1 and JS-335.

The frequency of chlorophyll mutations on M₁ family basis were found highest in 20 kR gamma-rays and 0.10% EMS concentration in both the varieties.  Similarly the mutations frequency of chlorophyll mutants on M₂ plant basis were highest in 25 kR gamma-rays dose in both the varieties while 0.10% EMS concentration in PKV-1 and 0.15% in JS-335 produced highest frequency of chlorophyll mutations. The similar results were also observed by Badaya and Mehrotra ^[12]; Constanin ^[13]; and Wakode ^[14] in Soybean and Nandanwar and Khamankar ^[15] in Mung bean.

However, gamma-rays in both the varieties were found most effective in inducing chlorophyll mutations than EMS.  Gamma-rays and EMS both induced maximum chlorophyll mutations namely Albina, Xantha, Alboviridis, and Chlorina.

Similar spectrum of chlorophyll mutations were also reported by Rajput and Sarwar ^[16] in Soybean ^[17] in Pigeon pea ^[18] in gram pea, ^[19] in soybean. The order of frequency of chlorophyll mutations induced by various mutagens in PKV-1 can be represented as Xantha > Chlorina> Alboviridis > Albina and in JS-335 can be represented as Xantha > Chlorina > Alboviridis > Albina (Table 3).

 

Table 3: Frequency spectrum of chlorophyll mutations as influenced by different mutagens

Treatment	No. of M2 plants	Chlorophyll mutants				Mutation frequency
		Albina	Xantha	Alboviridis	Chlorina	M1 family basis	M2 family basis
PKV-1
Control	2534
15 kR γ rays	2460	0.12	0.49	-	0.29	5.56	0.89
20 kR γ rays	2009	0.20	0.78	0.20	-	13.33	1.20
25 kR γ rays	1985	0.20	0.81	-	0.46	4.44	1.20
30 kR γ rays	1913	0.31	0.42	0.47	0.16	11.11	1.36
0.05 % EMS	2260	0.13	0.21	-	0.31	13.33	0.66
0.10% EMS	1860	-	0.32	0.48	0.60	17.78	1.39
0.15% EMS	1948	0.05	0.21	0.46	0.46	7.77	1.19
JS- 335
Control	2753
15 kR γ rays	2640	0.19	0.30	0.11	0.03	6.67	0.64
20 kR γ rays	2430	-	0.49	0.04	0.33	11.11	0.86
25 kR γ rays	2289	0.18	0.83	0.13	0.26	5.56	1.40
30 kR γ rays	2123	0.09	0.57	0.38	0.28	10.34	1.32
0.05 % EMS	2439	0.04	0.57	0.29	0.21	13.33	1.11
0.10% EMS	2386	0.04	0.38	0.50	0.38	16.67	1.30
0.15% EMS	2067	0.19	0.53		0.58	6.67	1.31

 

CONCLUSIONS- These mutants need to be studied in M₄ and onwards generation for purification and these mutants can be used for the improvement of soybean. The economical mutants provide base for selections for further generations which is the source of developing new lines also the large amount of the variability is created in the population which can be utilized as source for developing new lines for different desirable characters.

 

ACKNOWLEDGMENTS- The authors are highly grateful to the North Maharashtra University, Jalgaon and Principal of Institution to carry out the present investigation.

 

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