Науково-технічний бюлетень Інституту олійних культур НААН

Scientific and Technical Bulletin of the Institute of Oilseed Crops NAAS (ISSN: 2078-7316) / 2015 / 22 / P. 43-51
I.V. Totsky and V.A. Lyakh
Lyakh I.V. Totsky and V.A.
South regions of Ukraine are characterized by a constant lack of moisture. That is why it is necessary to carry out sunflower breeding for drought tolerance in order to maximize the productivity of culture in these conditions. One of the methods of plant breeding for resistance to stress factors is the selection of valuable genotypes at the level of gametophyte. In this approach the microgametophyte is most often used. Haploid genotype of pollen provides the expression of recessive genes, which often cause the economic value of cultivated plants. At present, a number of directions of pollen selection is formed. The list of environmental factors (both abiotic and biotic) and a range of crops where the possibility of gametophyte selection was shown are sufficiently broad. The gametophytic selection for drought tolerance was successfully carried out for such crops as flax, castor and sorghum. “Snegurochka” variety of japanese turnip, “Pamyati Zhigalova” variety of sweet pepper and “Pivdenna nich” variety of linseed are the examples of successful implementation of gametophytic selection method for resistance to various environmental factors into breeding practice. Sunflower is demanding to moisture, especially during flowering. Well-developed plants use from 500 to 600 mm of water during the growing season. The minimum water requirement is satisfied by 350-400 mm of rainfall. However, sunflower shows the relative drought resistance in some conditions due to the strong root system, which gives it the possibility to use effectively the soil water resources, including those accumulated during the winter. The aim of our study was to investigate the effect of F1 hybrids pollen heating and germination of F1 hybrids pollen under osmotic stress on drought resistance of F2 populations of cultivated sunflower, as well as to compare the effectiveness of these techniques. F1 hybrids of «virescent» ? «dichotomous venation» and «dichotomous venation» ? «xantha» cross combinations were used as the material of the study. Mutant lines of cultivated sunflower which contrasted in drought resistance were the parental components of hybrids. These mutant lines were developed at the Institute of oilseed crops of NAAS. Gametophytic selection for drought tolerance was carried out by two methods. In the first case, pollen heating was performed. Fresh pollen was collected from not emasculated inflorescences of hybrid plants. Part of this pollen was placed in open parchment packets in a layer of 1–3 mm height and heated in air bath oven at the temperature of 60 ± 2°C for a period of 1 hour. Then heated pollen was used for pollination of previously emasculated inflorescences of hybrids. Fresh pollen was used for pollination in the control. In the second procedure, for gametophytic selection for drought tolerance the stigmas of previously emasculated hybrid plants were treated with 10% PEG 6000 solution. After solution dried the on the stigmas the pollination was carried out with F1 hybrid fresh pollen. In the control, before pollination emasculated stigmas of hybrid plants were treated with the water. Drought resistance of F2 populations was determined using seed germination on sucrose and PEG 6000 solutions. After 3 (PEG) - 4 (sucrose) days the percentage of germinated seeds was counted. Germinated and not germinated in osmotic solution seeds were separately planted in boxes in a phytotron. The genetic structure of F2 populations for «dichotomous venation» and «virescent» marker traits was analyzed at the stage of the second pair of true leaves. The significance of differences was evaluated using Student's t-test. Studies on influence of F1 hybrid pollen heating on the quality of F2 sporophytic populations showed that this technique can not only change the heat resistance of segregating populations, but its drought resistance as well. The heating of F1 hybrid pollen of sunflower «xantha» ? «dichotomous venation» cross combination increased drought resistance of F2 sporophytic population. Drought resistance was estimated by seed germination in a 15% sucrose solution. It was more than 6 times higher compared with the seed germination of F2 population resulting from the pollination of F1 hybrids with fresh pollen. Pollen treatment of «virescent» ? «dichotomous venation» F1 hybrid with high temperature increased the part of F2 seeds germinated in a 20% PEG 6000 solution up to 58.8% in comparison with the control, where the percentage of seed germination in osmotic was equal to 19.2%. The pollen germination of the same hybrid on the stigmas in the presence of 10% PEG 6000 solution increased the percentage of F2 seed germination in osmotic approximately the same as the pollen heating. It should be noted that gametophytic selection, which takes place during pollen germination in the presence of osmotic, changed the genetic structure of F2 populations for some marker traits. After pollen germination on the stigmas, treated with 10% PEG 6000 solution, the number of F2 plants with the «virescent» chlorophyll mutation was larger as compared with the control. However, no changes were observed in segregation compared to control by «dichotomous venation» marker trait. A similar pattern was observed after analysis of the most drought-resistant part of F2 segregating populations. Pollen heating of F1 hybrids was characterized by the same effect. It can be concluded that the genes which define the sunflower drought resistance were apparently linked to the genes determining «virescent» marker trait.
Citation: Lyakh, I. T. A. V. (2015). I.V. Totsky and V.A. Lyakh. Scientific and Technical Bulletin of the Institute of Oilseed Crops NAAS, 22, 43-51.
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