Polyploidy in table beet breeding

Abstract

The article highlights the results of studies on the use of polyploidy in breeding table multi-germ beet, when new genotypes are obtained by seed treatment with colchicine. Genomic variability of polyploid forms is described, and expediency and importance of them in further breeding are defined.

The aim and tasks of the study. To establish the range of genomic variability in polyploid beet accessions and to estimate their economic value for breeding.

Material and methods. At the Institute of Vegetables and Melons NAAS, studies on obtaining polyploid forms of table beet have started since 2000. By pre-sowing treatment of seeds with 0.05% colchicine solution, polyploid forms were experimentally created. The action of colchicine on the structure of cell populations in cotyledon leaves in terms of ploidy was studied by the method developed by MV Roik, NS Kovalchuk (2003) at the Institute of Bioenergy Crops and Sugar Beet NAAS. 

Results and discussion. The results showed that in colchicine-generated polyploid form from variety ‘Diy’ expression of phenotypic variability in beetroot shape was observed in comparison with the untreated standard. The shape changed from roundish with downward inclination to conical or oval with upward inclination. Polyploid accession derived from variety ‘Bordo Kharkovskiy’ changed roundish beetroot with upward inclination to roundish-flat or oval with upward inclination.

Changes in beetroot shape is a positive effect of colchicine, because upward inclination of beetroots correlates with disease resistance and shallow soil location of beetroots. The use of such forms allowed us to predict creation of new genotypes resistant to diseases, with in-soil depth of 1/3, which will greatly reduce expenses for digging down during beetroot harvesting and increase output of healthy beetroots during storage.

It was found that the yield of polyploid accession K 1975 from early-ripening variety ‘Diy’ exceeded that of the original form by 4.6 t / ha, while K 1792 from early-ripening variety ‘Bordo Kharkovskiy’ – by 6.3 t / ha. There was an upward trend in the yield of typical beetroots and their biochemical composition. Cytophotometry of genomic variability of polyploid accession seeds in terms of ploidy degree showed that accession K 64-226 had 2х – 15, 3х – 2, 4х – 29, mixoploids – 4, whereas K 66-227 – 4x – 25 and mixoploids – 24.

Conclusions. By experimental polyploidy (several-fold increase in the chromosome number), the effect of gene dosage and genomic status of plants were determined according to increased values of quantitative and qualitative traits. Cytophotometry of genomic variability of seed accessions in terms of ploidy degree identified polyploid forms K 1839 and K 1838, which were used as source forms for F₁ hybrids. New polyploid forms have signal economically valuable traits of beetroot shape with upward inclination, yield capacity of 48.6 and 53.2 t / ha, dry matter content of 17.32 and 15.44%, total sugar of 9.88 and 8.82%, vitamin C content of 7.34 and 5.24 mg /100 g, betanin content of 279.75 and 230.20 mg /100 g, respectively.