Vegetative Segregation Research Articles

Crosses between Hordeum vulgare L. and H. bulbosum L. I. Production, morphology and meiosis of hybrids, haploids and dihaploids

From crosses between diploid and autotetraploid cytotypes of Hordeum vulgare L. (cultivated barley) and H. bulbosum L. (bulbous barley grass) diploid, triploid and tetraploid interspecific hybrids were produced. Both directly and after vegetative segregation crosses in either direction also gave rise to haploids and dihaploids resembling H. vulgare. The use of embryo culture was necessary. Plant morphology of the hybrids was much like that of H. bulbosum, although the hybrid plants were less vigorous. Meiosis in the hybrids was more or less disturbed, and this seemed to be the main cause of the high level of sterility.

Acriflavine-resistant mutants of Aspergillus nidulans.

SUMMARY: In three independently obtained mutant strains of Aspergillus nidulans, resistant in different degrees to acriflavine, resistance is due, in each case, to mutation in a single gene. Two of the mutant alleles, ACR1 and ACR3, are semi-dominant and either allele confers a high degree of resistance. These alleles are located about 23 units distal to the w (white conidia) locus and are presumably allelic. A cross involving these two alleles in repulsion gave 0.1% sensitives. A third mutant allele (acr2) is also located on the w chromosome, but on the other arm about 25 units distal to the ad1 locus and over 100 units distant from the ACR1 and ACR3 loci. This allele, which confers relatively slight resistance, is almost completely recessive. Diploid strains which carry any allele for resistance in heterozygous condition give, by vegetative segregation, haploid and homozygous diploid resistant types which are preferentially selected on medium with acriflavine. The use of this technique for the automatic selection of vegetative segregants provides an additional tool for analyses through the parasexual cycle.

Vegetative segregation in a hybrid race

Vegetative segregation in a hybrid race