Arne Müntzing

Accessory chromosomes in Poa alpina.

IN a strain of Poa alpina the chromosome conditions were found to be remarkable, a higher number of chromosomes being present at meiosis in the p.m.c. than in the root tips (Muntzing, i 946a). Root tips were fixed from seedlings grown in small pots. Counts from this material showed that most of the plants had 2fl = 14, the remaining plants being triploid or approximately triploid. Preliminary studies of meiosis in 5 plants, found to have n = 14 in the root tips, revealed the presence of more than 14 chromosomes in the p.m.c. of all these plants. In the best slide the p.m.c. had i chromosomes, the most frequent first metaphase associations of these chromosomes being 9jj+Ii and 8 + 3i These preliminary observations have now been extended. Altogether somatic counts have been made in about 300 plants, representing three generations. Meiotic data are available from a total of 35 individuals. Root tips were fixed in chrome-acetic-formalin after treatment with low temperature (about 00 (1) the night before fixation. For meiosis fixation with chrome-acetic-formalin following pre-treatment with acetic alcohol gave very poor results, whereas Benda proved to be more satisfactory. Root tips as well as spikelets were sectioned and stained with crystal violet. Pollen mitosis may be studied with some difficulty, but so far only aceto-carmine gave satisfactory results. Attempts to stain with Feulgen were not successful.

Problems of allopolyploidy in triticale.

Intergeneric allopolyploids combining genomes of bread wheat (Triticum aestivum) and rye (Secale cereale) were first produced by Rimpau (1). The true breeding strain which he had produced attracted great attention and was regularly cultivated for a long time in a plant breeding garden in Halle, Germany. According to Tschermak (2), this strain had also been cultivated for more than 40 years in the garden of the Agricultural University of Vienna.