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Cytological Effect of Gamma Radiation on Selected Mutants of Wheat Triticum aestivum L. in M3 Generation



Hussah I. Algwaiz
 
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ABSTRACT

Background and Objective: Wheat (Triticum aestivum L.) offers some unique opportunities for the induction and exploitation of agronomic value. The use of gamma radiation has been proven to be an effective method to induce genetic variation in crops. We aimed to determine genetically stable mutants of wheat which could be utilized for breeding purposes. Materials and Methods: We did a cytological investigation of induced mutant’s behavior and chiasma frequency. Selected mutant types induced in dry and soaked seeds were treated with different doses of gamma rays. Each treated sample and control were subjected to cytological examination of the fixed pollen mother cells in various meiotic stages. Results: The percentage of the total abnormal cells significantly increased in one mutant and significantly decreased in the other mutant. The percentage of total abnormal cells did not diminish from the first to the second meiotic division. The types of meiotic anomalies found included laggards (56.51%), univalent (9.43%), stickiness (45.45%) and bridges (19.32%). There were genotypic differences in the frequency of occurrence of multivalent (trivalent and quadrivalents). A marked reduction in the number of rod and ring bivalent/cell in some genotypes were noticed. The frequency of chiasmata per pollen mother cell was reduced subsequently. Depression index of mutants was negative compared with controls or treatments except for a few genotypes. Conclusion: Selected mutants of wheat tend to be cytologically stable and can therefore, be utilized for breeding purposes.

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  How to cite this article:

Hussah I. Algwaiz , 2019. Cytological Effect of Gamma Radiation on Selected Mutants of Wheat Triticum aestivum L. in M3 Generation. Pakistan Journal of Biological Sciences, 22: 607-613.

DOI: 10.3923/pjbs.2019.607.613

URL: https://scialert.net/abstract/?doi=pjbs.2019.607.613
 
Copyright: © 2019. This is an open access article distributed under the terms of the creative commons attribution License, which permits unrestricted use, distribution and reproduction in any medium, provided the original author and source are credited.

INTRODUCTION

Wheat (Triticum aestivum L.) offers some unique opportunities for the induction and exploitation of agronomic value. The use of gamma radiation has proved to be an effective method to induce useful mutation in several crops including wheat, red pepper, okra and maize1-5.

Induction of genetic variation through gamma irradiation induced higher genetic variation of up to 4 times in Bambara groundnut6. The use of ionizing radiation (including x-rays, gamma rays, neutrons and chemical mutagens) has been used to improve major crops including wheat, barley, cotton, peanuts and beans7. It is considered the only accurate and efficient judgment for the achieved genetic stability and regeneration in the progenesis of selected mutants8,9. Some mutagens directly alter specific chromosomal proteins and these chromosomal aberrations occur during meiotic division10. Chromosomal aberrations including laggards, c-mitosis, multipolar chromosomes with or without spindles, stickiness, premature bivalent, tripolar cells, fragments and bridges, dysjunction and micronuclei occurred following irradiation of T. aestivum L.11-13.

However, despite the well-known effect of gamma rays on plant growth and development by inducing morphological, cytological and physiological changes in the cells and tissues, there are few studies that investigated the genetic stability to yield a better agronomic value of wheat. Therefore, we aimed to determine genetically stable mutants which could be utilized for breeding purposes.

MATERIALS AND METHODS

Study setting and date of study: This study was conducted at the Department of Biology laboratory of Princess Noura bint Abdulrahman University in Riyadh, Saudi Arabia between May and December, 2018 (7 months).

Sample collection and preparation: Samples were collected from the markets in Riyadh, Saudi Arabia. In this study, samples were divided into 2, dry and soaked seeds and were treated with different doses of gamma rays. Each treated sample and control were subjected to cytological examination of the fixed pollen mother cells in various meiotic stages.

Irradiation of samples: Dry and soaked seeds of 3 lines of bread wheat L (5-130), (17-41-90) and (15-3-83) named L1, L2 and L3 were irradiated with 500, 5,000 and 10,000 rad of gamma rays. Treated and untreated seeds were grown in a completely randomized block design with 4 replications in wire cage houses. Selected mutants were carried out using the induction mutations in plant breeding suggested by Gottchalk and Wolff14. Table 1 shows the mutant strains and the controls used in the study.

Cytological examination: For the cytological study in M3, immature spikes from mutants, their treatments and control were fixed in Camoy’s mixture (6 parts absolute ethanol: 3 parts glacial acetic acid and 1 part chloroform) for 24 h at room temperature. Fixed spikes were washed with 70% ethanol twice and kept in the refrigerator until used. Anthers of suitable size were smeared in acetocarmine stain.

Table 1:
Mutant strains against their respective control
**Highly significant, *Significant

Analysis of samples: The types and frequencies of meiotic irregularities were recorded at metaphase I (MI), anaphase I (AI), metaphase II (MII) and anaphase II (AII). Chiasma frequencies were determined from MI. The percentage of reduction in chiasma frequency was measured as depression index using the equation:

where, A is the number of chiasma in control plants and B is the number of chiasma in the mutant or treated plants.

Statistical analysis: Data was analyzed using the Statistical Package for Social Sciences (SPSS) version 23.0 (SPSS Inc, Armonk, New York, USA). Results were expressed as numbers and percentages for categorical variables and as mean and standard deviation for continuous variables. Analysis of variance (ANOVA) was done and the least significant difference (LSD) was taken for comparison between genetic materials. One-way analysis of variation (ANOVA) was used to test the significant difference between 2 groups. A p<0.05 was considered statistically significant.

RESULTS

The cytological data for the different genetic materials (genotypes) examined are summarized in Table 2-5. Table 2 shows that the genotypes exhibited significant differences at meiotic stages.

The number of pollen mother cells (PMC’s) observed and the number of abnormal cells in each stage of meiotic division for genotypes is shown in Table 3. The percentage of abnormal cells showed a significant decrease in some meiotic stages for all mutants when compared with the control or treatments except mutant-19 which showed a significant increase for MI and AII and mutant-2 in MI. The percentage of abnormal PMC’s did not decrease from MI-MII.

Abnormal cells: The percentage of total abnormal cells, types of meiotic anomalies as laggards, univalent, stickiness and bridges are shown in Table 4. The percentage of total abnormal cells showed significant decrease and increase for mutant-12 and 19, respectively. Another variable proportion at MI of cells was univalent (1.49-9.43%) for control (L2 cs) and mutant-19, respectively. The univalent accumulated in the equatorial region during MI and gave rise to lagging chromosome at AI in PMC’s. Sticky metaphases were observed in the genetic materials. The lowest percentage was 28.31% for mutant-19. At ana-telophase stages, bridges were observed. The variable proportion percentage ranged from 5.04-19.32%.

Chiasma frequencies: Table 5 shows the chiasma frequencies in wheat which showed marked reduction in the mean number of rod and ring bivalent per cell for mutant-7 and mutant-19 compared to the control and treatments. The maximum extent of reduction in the mean number of rod and ring bivalent/cell was 7.66±0.57 and 7.44±0.47 for mutant-7 and 19, respectively. Multivalents ranged from trivalents to quadrivalents. There were genotypic differences in the frequency of occurrence of multivalents.

Depression index: Depression index was negative when mutants were compared with the control except for mutants-3, 8, 17 and 19. Negative values were obtained when mutants were compared with their treated counterparts except for mutant-19. The frequency of chromosomal aberrations in the genotype were as near as the control except for one mutant. On the contrary, chiasma frequency increased as the control for the mutants. These results indicated that selected mutants tend to be cytologically stable.

DISCUSSION

This study showed that the genotypes exhibited significant differences at meiotic stages. Apparently, genetic differences within this population may have contributed to the differences in the stages among genotypes. Furthermore, the significant decrease in the percentage of abnormal cells in some meiotic stages for all mutants can be attributed to either no recovery or no elimination of abnormal PMC’s during the course of meiotic division. However, this finding is in contrast to that of Kalinka et al.15 where they reported that elimination of PMC’s occur before and after meiosis as well as in each stage of meiotic division.

Table 2:
Mean squares for the percentage of abnormal cells in different meiotic stages of wheat (control, treatments and their mutants) in M3 generation
**Highly significant, *Significant

Table 3:
Number and percentage of abnormal meiotic cells of wheat (control, treatments and their mutants) in M3 generation
*,**Significant between mutant with control, +,++ Highly significant between mutant with treatment, L: Line, Mut: Mutant, D: Dry seeds, S: Soaked seeds, Abn: Abnormal, kr: Kilorad

Table 4:
Percentage of the occurring abnormalities on meiosis of wheat (control, treatment and their mutants) in M3 generation
*Significant, **Highly significant, kr: Kilorad D: Dry seeds, S: Soaked seeds, PMC: Pollen mother cells, L: Line, Mut: Mutant, N: Number

They further suggested that the phenomenon of direct chromosome/chromatin elimination from PMC’s leads to irregular meiosis and disturbances in the meiotic process and nucleoli are the first ones to be eliminated.

The significant decrease in the percentage of total abnormal cells can be attributed to homozygosity, genetic stability and recovery from irradiation damage. Genetic materials have exerted some effect on spindle formation or action as manifested by the presence of variable proportions of cells with laggard (35.8-56.5%) similar to findings by Kumar and Rai16,17. Chromosomal anomalies including stickiness, univalent, multivalents at metaphase and bridges, laggards and polyads are found at anaphase and telophase stages18. Univalents may result from the failure of chromosomes to pair at zygotene (asynapsis) or from the disjunction of homologous chromosomes at diplotene (desynapsis) because chiasma formation did not occur. The functional gametes, formed from such abnormal cells may result in an aneuploidy progeny and may induce significant changes in multiple phenotypic traits including cytosine DNA methylation patterns19. Chromatin stickiness may be caused by some changes in the surface properties of the chromosomes which caused them to adhere to each other. Metaphases with sticky chromosomes loses their normal appearance and they appear as agglomerated chromosomes due to effect of pollutants and chemical compounds where complexes are formed with the phosphate groups in DNA, condensation of the DNA or formation of chromatid cross links20. The formation of bridges may be due to the broken ends containing centromere from 2 different chromosomes that unite to form dicentric chromosomes or chromosomes are clumped together due to stickiness and are unable to separate completely at anaphase, or centromere inactivation resulting in dicentric chromosomes21,22. The marked reduction in the mean number of rod and ring bivalent/cell for mutant-7 and 19 and the presence of multivalents were also found in this study. Multivalents ranged from trivalents to quadrivalents. There were gentotypic differences in the frequency of occurrence of multivalents.

The differences in chiasma frequency genotypes indicated that the formation of chiasma is controlled by polygenes and it has a profound effect on the distribution of the various chromosome configurations at meiosis. Chiasmata that holds homologous chromosomes together prevent premature disjunction and if separated can result in laggard chromosomes23. This may be due to the homozygosity, genetic stability and general recovery from the irradiated damage in M3 generation. On the contrary, chiasma frequency increased as the control for the mutants.

Table 5:
Chiasma frequencies in wheat (control, treatments and their mutants) in M3 generation
L: Line, Mut: Mutant, D: Dry seeds, S: Soaked seeds, Treat: Treatment, C: Control, kr: Kilorad

CONCLUSION

Meiotic anomalies including laggards, univalent, stickiness and bridges with irradiation were found with gamma radiation. Genotypic differences occur as trivalents and quadrivalents. There were also marked reduction in the number of rod and ring bivalent/cell and also with the frequency of chiasmata/pollen mother cell. Depression index of mutants was negative in most of the genotypes. Selected mutants of wheat tend to be cytologically stable and can therefore be utilized for breeding purposes.

SIGNIFICANCE STATEMENT

This study discovered the cytological effects of gamma radiation on selected mutants of wheat (Triticum estivum L.) in the third mutation (M3) that can be beneficial for improving crops. This study will help the researchers to uncover the critical areas of the usefulness of gamma radiation in improving crops that many researchers continue to explore.

ACKNOWLEDGMENT

This research was funded by the Deanship of Scientific Research at Princess Nourah bint Abdulrahman University through the Fast-track Research Funding Program

REFERENCES
1:  Melki, M. and A. Marouani, 2010. Effects of gamma rays irradiation on seed germination and growth of hard wheat. Environ. Chem. Lett., 8: 307-310.
CrossRef  |  Direct Link  |  

2:  Singh, B. and P.S. Datta, 2010. Gamma irradiation to improve plant vigour, grain development and yield attributes of wheat. Radiat. Phys. Chem., 79: 139-143.
CrossRef  |  Direct Link  |  

3:  Kim, J.H., B.Y. Chung, J.S. Kim and S.G. Wi, 2005. Effects of in Planta gamma-irradiation on growth, photosynthesis and antioxidative capacity of red pepper (Capsicum annuum L.) plants. J. Plant Biol., 48: 47-56.
CrossRef  |  Direct Link  |  

4:  Hegazi, A.Z. and N. Hamideldin, 2010. The effect of gamma irradiation on enhancement of growth and seed yield of okra [Abelmoschus esculentus (L.) Monech] and associated molecular changes. J. Hortic. For., 2: 038-051.
Direct Link  |  

5:  Marcu, D., G. Damian, C. Cosma and V. Cristea, 2013. Gamma radiation effects on seed germination, growth and pigment content and ESR study of induced free radicals in maize (Zea mays). J. Biol. Phys., 39: 625-634.
CrossRef  |  Direct Link  |  

6:  Adu-Dapaah, H.K. and R.S. Sangwan, 2004. Improving bambara groundnut productivity using gamma irradiation and in vitro techniques. Afr. J. Biotechnol., 3: 260-265.
Direct Link  |  

7:  Ahloowalia, B.S. and M. Maluszynski, 2001. Induced mutations-A new paradigm in plant breeding. Euphytica, 118: 167-173.
CrossRef  |  Direct Link  |  

8:  Khan, S. and S. Goyal, 2009. Mutation genetic studies in mungbean IV. Selection of early maturing mutants. Thai J. Agric. Sci., 42: 109-113.
Direct Link  |  

9:  Patade, V.Y. and P. Suprasanna, 2008. Radiation induced in vitro mutagenesis for sugarcane improvement. Sugar Tech., 10: 14-19.
CrossRef  |  Direct Link  |  

10:  Baptista-Giacomelli, F.R., M.S. Palgliarini and J.L. de Almeida, 2000. Meiotic behavior in several Brazilian oat cultivars (Avena sativa L.). Cytologia, 65: 371-378.
CrossRef  |  Direct Link  |  

11:  Kumar, S., 2010. Effect of 2,4-D and isoproturon on chromosomal disturbances during mitotic division in root tip cells of Triticum aestivum L. Cytol. Genet., 44: 79-87.
CrossRef  |  Direct Link  |  

12:  Kikuchi, S., Y. Saito, H. Ryuto, N. Fukunishi, T. Abe, H. Tanaka and H. Tsujimoto, 2009. Effects of heavy-ion beams on chromosomes of common wheat, Triticum aestivum. Mutat. Res./Fund. Mol. Mech. Mutagen., 669: 63-66.
CrossRef  |  Direct Link  |  

13:  Han, R., X.L. Wang, M. Yue and Z. Qi, 2002. Effects of the enhanced UV-B radiation on the body cell mitosis of the wheat. Acta Genet. Sin., 29: 537-541.
PubMed  |  Direct Link  |  

14:  Gottschalk, W. and G. Wolff, 2012. Induced Mutations in Plant Breeding. Vol. 7. Springer Science & Business Media, Switzerland.

15:  Kalinka, A., M. Achrem and S.M. Rogalska, 2010. Cytomixis-like chromosomes/chromatin elimination from Pollen Mother Cells (PMCs) in wheat-rye allopolyploids. Nucleus, 53: 69-83.
CrossRef  |  Direct Link  |  

16:  Kumar, G. and P.K. Rai, 2007. EMS induced karyomorphological variations in maize (Zea mays L.) inbreds. Turk. J. Biol., 31: 187-195.
Direct Link  |  

17:  Kumar, G. and P.K. Rai, 2009. Genetic repairing through storage of gamma irradiated seeds in inbred maize (Zea mays L.). Turk. J. Biol., 33: 195-204.
Direct Link  |  

18:  Khan, Z., H. Gupta, M.Y.K. Ansari and S. Chaudhary, 2009. Methyl methanesulphonate induced chromosomal variations in a medicinal plant Cichorium intybus L. during microsporogenesis. Biol. Med., 1: 66-69.
Direct Link  |  

19:  Gao, L., M. Diarso, A. Zhang, H. Zhang and Y. Dong et al., 2016. Heritable alteration of DNA methylation induced by whole-chromosome aneuploidy in wheat. New Phytol., 209: 364-375.
CrossRef  |  Direct Link  |  

20:  Celik, T.A and O.S. Aslanturk, 2010. Evaluation of cytotoxicity and genotoxicity of Inula viscosa leaf extracts with allium test. J. Biomed. Res., 10.1155/2010/189252

21:  Han, F., J.C. Lamb and J.A. Birchler, 2006. High frequency of centromere inactivation resulting in stable dicentric chromosomes of maize. Proc. Natl. Acad. Sci. USA., 103: 3238-3243.
CrossRef  |  Direct Link  |  

22:  Friebe, B., R.G. Kynast and B.S. Gill, 2000. Gametocidal factor-induced structural rearrangements in rye chromosomes added to common wheat. Chromosome Res., 8: 501-511.
CrossRef  |  Direct Link  |  

23:  Souza, M.M. and T.N.S. Pereira, 2011. Meiotic behavior in wild and domesticated species of Passiflora. Braz. J. Bot., 34: 63-72.
CrossRef  |  Direct Link  |  

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