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Nine strains of tetraploid red clover obtained from forms producing of male and female gametes were studied. Tetraploids received from unreduced gametes appeared to be characterised by favourable parameters of seed yield structure traits. The yield of strains 4x was higher than that of colchiploids. Genetic variability obtained by crossing of forms producing unreduced male and fornale gametes resulted in better seed set increasing breeding and usability value of tetraploid red clover.
This study was aimed at developing an efficient protocol for regeneration of Pseudostellaria heterophylla plantlets and induction of polyploidy. Calli of P. heterophylla (Miq) from stems, leaves and buds as explants could not differentiate into plantlets. However, young embryo segments used as primary explants produced embryonic calli on MS medium containing 5.0 mg/L 2,4-D and 0.5 mg/L KT. After the embryonic calli with granular protuberances were transferred to MS medium containing 0.5 mg/L BA, they developed shoots and then rooted to form plantlets. Polyploidy was induced when embryonic calli were placed in liquid MS medium containing 0.5% colchicine for 4 days, followed by culturing in solid medium to induce differentiation. Polyploidy was identified by the number of chromosomes and the size of plantlet stomata. The tetraploid plantlets produced larger root tubers than the diploid plantlets.
Within the years 1996-2005 at Plant Breeding and Acclimatization Institute, Research Division Młochów genetic variation of 2x potato was being transferred into 4x level in interploidy crosses 4x-2x. In eight crossing cycles 233 combinations of 4x progenies were obtained. Out of them 57 were used in tetraploid parental breeding lines. They were obtained among 16 diploid donors of new alleles of chosen traits and 23 tetraploid females. Efficiency of seed setting in these crosses ranged from 0.9 to 171.0 seeds per berry. As a result of selection and comparative analysis among the progenies originating from 4x-2x crosses and standard 4x-4x progenies, 2x clones were distinguished as perspective parents for tetraploid breeding. They were as follows: HT/HZ 84-PH 151, DG 88-89, DW 88-4556, DG 93-332 and DG 97-943 for processing; DG 88-89 and DW 88- 4556 for table use; HT/HZ 84-PH 151 for high starch content; DG 91-234 for resistance to Phytophthora infestans and DG 88-9 for resistance to Erwinia carotovora.
In 1996 at the Plant Breeding and Acclimatization Institute, Research Division Młochów breeding of improved parental lines started in order to accelerate the development of potato cultivars suitable for processing. Parental lines were derived from specific hybridizations between West-European or North-American cultivars with a high processing quality and our own genotypes with an increased dry matter content, light colour of fried product and multiply virus resistance (PVX, PVY, PVM, PLRV). Among eleven parental lines that were supplied to Polish breeders in 1999-2005, nine are „cold chipping” type with a light colour of fried product after a cold storage at 4-5ºC. A high potential advance of the released parental lines by selection for chip colour was expressed by the estimates of: genetic variance (δ²g), heritability (h²), progressin chip colour (R) and the presence of positive effects of general combining ability in pilot progenies. The valuable feature of the released parental lines in comparison with the leading foreign cultivars used in processing industry in Poland is their higher resistance to a common and necrotic strain of PVY.
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