Cytogenetical Studies on Intergeneric Hybrids between Haynaldia and Secale

V. External Characteristics and Meiosis in PMC's of SfHvSaF₁ Plant

Abstract

1. In the present report, the external characteristics, the number of somatic chromosomes and the meiosis in PMC's of a plant, thought to be raised from natural crossing SfHvF₁ with Secale africanum growing around it, were described, and the plant will be represented as SfHvSaF₁-1.
2. The somatic number of chromosomes of the SfHvSaF₁-1 plant was counted to be 21 (Fig. 1). This was probably caused by the fertilization of the female gamete of the SfHvF₁ plant (2n=14) having 2n chromosomes with pollen of S. africanum (n=7) growing around it, viz. 14+7=21.
3. The culm height of SfHvSaF₁-1 was intermediate between the parents, but it was much inferior to that of SfHvF₂ plant, while the length of spikes shows almost the same value to that of the SfHvF₂ plants. The length of awns was intermediate between the parents, but it was inferior to that of SfHvF₂ plants. The number of spikelets and spike density are rather closely resembled the SfHvF₁ as the mother plant, but these were considerably superior to those of SfHvF₂ plants. The number of florets per spikelet was inferior to that of the mother plant (SfHvF₁), but its value was almost the same as that of the pollen parent. The number of tillers was somewhat superior to that of the SfHvF₂ plant but it was considerably inferior to that of the parents.
4. The number of chromosomes in PMC's was 21 in the total as the 2n number (Figs. 2-9). Among them 7 chromosomes most probably have been derived from pollen parent, S. africanum (n=7), and also the remaining 14 must have been derived from the mother plant, SfHvF₁ (2n=14). Therefore, the genomes of this plant, SfHvSaF₁-1, will be VR^aR^f.
At MI of PMC's 0-7 bivalents were found. Their frequencies are shown in Table 2. The mode of occurrence of bivalents was 5, and average value of the bivalents was 3.85.
Most of the bivalents may be caused by the syndesis between the chromosomes of R^a and R^f genomes of S. africanum and S. fragile respectively.
Trivalents besides bivalents were rarely observed.
5. This SfHvSaF₁-1 plant was completely sterile.