Suillus and Boletinus were studied using Ohta medium. In media with glucose or trehalose, all tested strains grew well. With mannose and cellobiose, strains generally grew well, except for one strain of Suillus. Utilization of dextrin and soluble starch differed with each strain, and that of sucrose and glycerol was low for all strains. Utilization of four amino acids, arginine, glutamic acid, aspartic acid, and alanine, was similar to that of ammonium tartrate for Suillus strains, but mycelial growth with amino acids was clearly lower than with ammonium tartrate for the Boletinus strain. The effect of glucose and ammonium tartrate concentrations for nine strains of the genera Suillus and Boletinus was studied with ranges for glucose of 1-100 and 200 g/l, respectively, and for ammonium tartrate of 0.2-5 and 20 g/l, respectively. Six strains showed maximal growth at a glucose concentration greater than 25 g/l, and one strain showed maximal growth at 70 g/l. The results indicate that these fungi are adapted to relatively high concentrations of carbon sources. In general, glucose concentration at mycelial growth maximum decreased as ammonium tartrate concentration increased, and at higher concentrations of glucose, mycelial growth decreased more rapidly in higher concentrations of ammonium tartrate.

A split-plate method with two media in different concentrations in each compartment was applied for the mycelial growth of four strains of Suillus luteus, S. grevillei, S. granulatus, and S. bovinus. As the glucose concentration in the A-side (the side containing higher concentrations of glucose) increased, the mycelial growth in both A-and Bsides (the side containing lower concentrations of glucose) increased. The mycelial density in both sides and B/A ratio (the ratio of the mycelial growth in the B-side to that in the A-side) also increased, and the colony morphology changed. In both A-and B-sides, the colony area reached maximum at 10 g/l glucose in the A-side in most cases and at 33.3 g/l in several cases. The results indicated nutrients are translocated from mycelia in the A-side to those in the B-side. High concentration of phosphate or fructose ϩ glucose in the A-side induced better mycelial growth in the B-side. Addition of high concentrations of phosphate to one side enhanced mycelial growth in the other side. Lowtemperature incubation promoted the growth in the B-side. Our split-plate culture method will be useful for qualitative study of translocation in ectomycorrhizal fungi.

No abstract

There are two growth types of plants for the number of developed leaves, heading time, and culm and panicle lengths within a population of a homozygous rice cultivar. However, this phenomenon has not been deeply investigated, because of lack of concrete data. Rice breeders and physiologists have paid little attention to it, regarding it as a genetically uncontrollable environmental variation. To study more details of the phenomenon, we grew two near-isogenic lines of rice with each one of the alleles for the Se1 locus conferring photoperiod sensitivity on chromosome 6 under natural long and short day-length conditions. In the line ER homozygous for the earliness allele Se1-e, and the line LR with the lateness allele Se1-u, N-leaf plants headed several days earlier than N+1-leaf plants. The N-leaf plants had shorter culms and longer panicles and were the upper-internode elongation type, whereas the N+1-leaf plants had opposite values of these characters. The proportion of these two kinds of plants changed in lines, plots and experiments. We discuss the meanings of this phenomenon from the viewpoints of rice cultivation to attain the uniform growth of plants, breeding to select individual plants with environmental variation, and fixation test to evaluate the uniformity needed as a cultivar.