1,720,978 research outputs found
Polyploid cytotypes and formation of unreduced male gametes in wild and cultivated fennel (Foeniculum vulgare Mill.)
No full textFoeniculum vulgare Mill. (2n=22) is an herbaceous species native to the Mediterranean region and naturalized in many temperate areas around the world. It includes subsp. piperitum and subsp. vulgare which are, respectively, the wild and cultivated forms. Fennel is of economic importance both as a vegetable crop and for its wide use in the food and pharmaceutical industries. In recent years, the therapeutic and pharmacological potential of this species has been widely analyzed, its cytogenetic traits have aroused less interest. Therefore, the intention of this study was to reduce this gap by investigating some aspects, such as the variations in its chromosome number and the occurrence of polyploidization events, so far neglected. By means of extensive chromosome counting, the presence of tetraploid cytotypes has been discovered both in the wild and cultivated fennel. Moreover, the analysis of pollen and PMCs at the tetrad stage provided evidence for spontaneous sexual polyploidization as the most probable origin of the tetraploid cytotypes discovered. The results of this study provide the first evidence of the occurrence of polyploidization events in F. vulgare and suggest that the use of 2n gametes could be a useful approach to genetic improvement of this crop
Linkage mapping in apomictic and sexual Kentucky bluegrass (Poa pratensis L.) genotypes using a two way pseudo-testcross strategy based on AFLP and SAMPL markers
No full textCytological, morphological and molecular analyses of controlled progenies from meiotic mutants of alfalfa producing unreduced gametes.
No full textA program of sexual polyploidization was carried out in alfalfa using plants from wild diploid species that produced male or female unreduced gametes. Sixteen progenies from 2x-4x and 2x-2x crosses were examined with a combination of morphological, cytological and molecular analyses. The chromosome counts revealed diploid, tetraploid and aneuploid plants. Plants with B chromosomes were also detected. The leaf area of the plants was a useful characteristic for distinguishing tetraploid from diploid plants obtained by unilateral or bilateral sexual polyploidization. Leaf shape and leaf margin were not correlated with the ploidy levels. Plants with supernumerary chromosomes displayed obovate or elliptic leaves which differed markedly from the range of forms typical of diploid and tetraploid alfalfa plants. RAPD markers were investigated in all progeny plants to determine maternal and paternal amplification products. Three alfalfa-specific primers proved to be effective in revealing the hybrid origin of the plants. A combination of cytological, morphological and molecular analyses is essential for a detailed genetic characterization of progenies in programs of sexual polyploidization
Enhancement of micronuclei frequency in the Tradescantia/micronuclei test using a long recovery time
No full textLinkage mapping in apomictic and sexual Kentucky bluegrass (Poa pratensis L.) genotypes using a two-way pseudo-testcross strategy based on AFLP and SAMPL markers
No full textThe high versatility of the mode of reproduc- tion and the retention of a pollen recognition system are the factors responsible for the extreme complexity of the genome in Poa pratensis L. Two genetic maps, one of an apomictic and one of a sexual genotype, were con- structed using a two-way pseudo-testcross strategy and multiplex PCR-based molecular markers (AFLP and SAMPL). Due to the high ploidy level and the uncertainty of chromosome pairing-behavior at meiosis, only parent- specific single-dose markers (SDMs) that segregated 1:1 in an F1 mapping population (161 out of 299 SAMPLs, and 70 out of 275 AFLPs) were used for linkage analysis. A total of 41 paternal (33 SAMPLs and 8 AFLPs) and 47 maternal (33 SAMPLs and 14 AFLPs) SDMs, tested to be linked in coupling phase, were mapped to 7+7 linkage groups covering 367 and 338.4 cM, respectively. The comparison between the two marker systems revealed that SAMPL markers were statistically more efficient than AFLP ones in detecting parent-specific SDMs (75% vs 32.4%). There were no significant differences in the per- centages of distorted marker alleles detected by the two marker systems (27.8% of SAMPLs vs 21.3% of AFLPs). The pairwise comparison of co-segregational groups for linkage detection between marker loci suggested that at least some of the P. pratensis chromosomes pair preferen- tially at meiosis-I
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