DIFFERENT PLOIDIES OBSERVED IN THE ROOT TIP MERISTEM OF PROGENIES OBTAINED BY GAMMA IRRADIATION (Co-60) OF PEA FLOWER BUDS
A pea variety (IP-1) was irradiated with a 20-kr dose in the initial phase of microsporogenesis. In seeds developed from the flower buds of peas irradiated about the time of meiosis, individuals of different ploidy were found by cytological examination of root tips. Chromosomes with three satellites were encountered in the chromosome set of the irradiated variety. Seven of 384 cytologically analyzed individuals were polyploid, which, apart from being a comparatively high number, is of theoretical significance on account of the observed difference in the degree of ploidy. In peas, polyploidy induced by gamma irradiation is noteworthy because polyploid individuals could not be produced either by colchicine or by use of other mutagenic agents. Compared to other ploidy types, triploidy induced in meiosis by irradiation occurs frequently. The conditions for the production of triploid peas are probably analogous to those previously studied in connection with the triploidy of sunflowers. The anomaly described in the second maturity division of microsporogenesis probably leads to the genesis of pollen with diploid generative nucleus which, if fertilized, results in tripolidy. While triploidy induced by irradiation is about 4% in the sunflower, it is 0.5% in peas. While only triploidy was observed in the sunflower, five other types of ploidy, with an approximate frequency of 1.3%, were found in the pea. Besides tetraploid, also hexaploid, nonaploid, decaploid, and dodecaploid chromosome sets were encountered. The occurrence of individuals of another than the triploid type was less frequent. Only the triploid and tetraploid individuals could be raised to the flower or mature seeds stage and then reproduced. Individuals of abnormal ploidity (nonaploid, decaploid, dodecaploid) died at the onset of vegetative development. It is suggested that polyploidy may be traced to structural changes in spindle fibers. (BBB)
- Research Organization:
- Agricultural Experimental Inst., Iregszemcse, Hungary
- NSA Number:
- NSA-18-013468
- OSTI ID:
- 4088035
- Journal Information:
- Acta Botan. Acad. Sci. Hung., Vol. Vol: 9; Other Information: Orig. Receipt Date: 31-DEC-64
- Country of Publication:
- Country unknown/Code not available
- Language:
- English
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