Регуляція морфогенезу in vitro у ліній кукурудзи групи Ланкастер
Regulation of in vitro morphogenesis in maize inbreds of the Lancaster group

Summary/Abstract: The aim of this work is the comparative evaluation of the influence of physiologically active substances (PAS) on the ratio of morphogenesis types in vitro and plant regeneration in callus tissues of maize inbreds of the Lancaster heterotic group. Lancaster inbreds of Ukrainian selection DК267, DК6080 and DК298 and lines PLS61, A188 and Chi31 of foreign selection which represented eponymous heterotic groups were selected for into the research. For callusogenesis induction immature embryos of 1.0–1.5 mm in length were planted on a modified N6 medium with 30 g/l sucrose. For regeneration the 30-day callus tissue was transplanted to a modified MS medium containing 20 g/l sucrose and various PAS: 6-benzylaminopurine (BAP) (0.1 mg/l) or indolylbutyric acid (IBA) (1.0 mg/l), or cefotaxime (CT) (150 mg/l). Morphogenesis and plant regeneration were obtained in callus tissue by organogenesis through the formation of leaf-like structures or shoots only without roots (hemmogenesis) and by embryogenesis through the development of embryos with the cooperative laying of the apexes of the shoot and the root. The predominant type of in vitro morphogenesis in both groups of genotypes was organogenesis. A tendency to increasing the embryogenesis level among Lancaster inbreds in comparison with the other investigated groups was observed. A certain tendency to increase the level of embryogenesis on a medium for regeneration with IBA, compared to other PAS, was marked. So, for the Lancaster group the embryogenesis level on the medium with IBA was 33.3%, while for the other investigated genotypes it was about 10.3%. Regeneration frequency was 45.8 plantlets/100 calli for Lancaster inbred DК298, 42.2 plantlets/100 calli for DК267 and 5.6 plantlets/100 calli for DК6080. Regeneration frequency of inbred PLS61 was 204.0 plantlets/100 calli, 100.0 plantlets/100 calli for Chi31 and 11.1 plantlets/100 calli for А188. Observed reductions in capacityf or plant regeneration of Lancaster inbreds may have been due to their pedigree. These inbreds belong to the commercial heterotic group that was not specially selected for increased regenerative ability, unlike the model inbreds of other heterotic groups. Overall, the level of regeneration frequency in the Lancaster group was 44.8 plantlets/100 calli on the medium under BAP, 41.4 plantlets/100 calli under IBA, and 20.7 plantlets/100 calli with CT. In general, the level of regeneration frequency for non-Lancaster heterotic groups reached 89.7 plantlets/100 calli on the medium with BAP, 96.7 plantlets/100 calli under IBA, and 93.1 plantlets/100 calli under CT. To enhance embryogenesis and frequency of regeneration for maize inbreds of the Lancaster group 30 g/l sucrose in the callusogenesis medium and physiologically active substance indolylbutyric acid (1.0 mg/l) in the medium for regeneration can be recommended.

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