Duplication of the genes for both wax production (W loci) and inhibition (proposed symbol, Iw loci) on chromosomes 2B and 2D hindered clarification of the allelic and linkage relationships between these loci in wheat. The near-isogenic lines of three genotypes, w1w1 w2w2, W1W1 w2w2 and w1w1 W2W2, for wax production (all iw1iw1 iw2 iw2 for wax inhibition) and two genotypes, Iw1Iw1 iw2 iw2 and iw1 iw1 Iw2Iw2, for wax inhibition (both W1W1 W2W2 for wax production) therefore were produced by ten backcrosses with Triticum aestivum cv. S615 (genotype W1W1 W2W2 iw1iw1 iw2iw2), or its equivalent w-S615 (w1w1 w2w2 iw1iw1 iw2iw2), as the recurrent parent. Segregation ratios between glaucous and non-glaucous plants in successive backcross generations or after selfing the backcrossed offspring indicated that all the wax-producing (W) and inhibiting (Iw) alleles were transmitted at equal frequencies to their respective recessive alleles, w and iw. Linkage analyses of W1, Iw1 and Ne2 (a gene for hybrid necrosis) on chromosome 2B and W2, Iw2 and C (a gene for compact ear) on chromosome 2D showed that the W1 and W2 loci respectively are located at sites different from the Iw1 and Iw2 loci. The presently accepted concept of multiple allelism for w, W and W^I (wax inhibition) therefore is invalid. Rather two allelic sets, w and W, and iw and Iw, both of which are duplicated on chromosomes 2B and 2D, must be postulated for the glaucousness of wheat. The first genetic maps showing their linkage relationships to the centromere and the Ne2 and C loci have been constructed.

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Two distinct crops of Perilla frutescens Britt. (Labiatae), leafy vegetable (var. crispa, shiso in Japanese) and oil crop (var. frutescens, egoma in Japanese) and the weedy type were investigated to clarify their genetic relationships. Twenty-five samples from Japan were analyzed by the RAPD technique with 40 random decamer primers and a phenogram was constructed based on RAPD using the neighbor joining method. Among 284 different bands detected, 124 (44%) showed polymorphisms. The weedy type Perilla was most variable with 76 (27%) polymorphic bands compared to 67 (24%) of var. crispa and 62 (23%) of var. frutescens. The weedy Perilla had only four unique bands, while var. crispa and var. frutescens had 13 and 14 unique bands, respectively. In the phenogram, var. crispa and var. frutescens each formed a cluster, whereas different samples of the weedy type occupied different positions in the tree. This implies that gene flow between the two crops is limited although they are artificially crossable with each other. The position of the samples of var. crispa and var. frutescens in the phenogram has no relationship with the geographical locations of the samples. Four out of six samples of the weedy type were situated on the branches connecting the crispa and frutescens groups in the phenogram. This may suggest that these samples originated from hybrids between var. crispa and var. frutescens.

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A gametocidal chromosome, chromosome 2C derived from Aegilops cylindrica, was introduced into six wheat-barley addition lines to establish chromosome-mutation- inducing lines. These lines, except the one for chromosome 4H, had a pair of respective barley chromosomes and one 2C chromosome (22"+1'); the line for 4H was doubly monosomic for chromosome 4H and chromosome 2C (21"+2'). In these lines, chromosome breaks were expected to occur in the gametes lacking chromosome 2C. The selfed and backcrossed progeny of these lines were cytologically investigated by in situ hybridization and N-banding. Various types of structural aberration like deletion and translocation were detected for all barley chromosomes with frequencies ranging from 10.8% to 27.9%. The highest frequency of aberrations occurred in chromosome 4H with most of the breakpoints localized in or near the centromeric region. A simplified procedure of in situ hybridization used in this study was suitable for the large-scale screening for barley chromosome aberrations in the background of wheat.

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Segregation of AFLP markers was frequently severely distorted when initial attempts were made to develop a molecular-based linkage map of sugi (Cryptomeria japonica). Only 27 out of 46 AFLP markers detected with combinations of three and four selective nucleotide primers (EcoRI + 3 and MseI + 4) fitted a 1:1 segregation ratio (α > 0.01). Greater selectivity was sought using M + 5 primers, derived by extending the original selective M + 4 primers with each possible additional nucleotide. More than 60% of all the fragments detected with M + 4 primers were amplified by at least two kinds of M + 5 primers. The results suggested that single fragments in the E + 3/M + 4 analysis were really fragment complexes in many cases. Of the 19 AFLP markers showing distortion, 13 were amplified by two to four of the M + 5 primers, but the level of distortion shown by these markers was reduced (or eliminated), when M + 5 primers were used. Thus, fragment complexes may be a major cause of segregation distortion. On the other hand, most of markers with a segregation that fitted the 1:1 ratio were amplified by a single M + 5 primer. In addition, E + 3/M + 4 primers detected a much greater frequency of polymorphism than E + 3/M + 5 primers in sugi. Therefore, we would recommend the use of both E + 3/M + 4 and E + 3/M + 5 primers for efficient AFLP mapping.

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For plant species reproducing both sexually and vegetatively, the spatial distribution of clones generally affects the levels of biparental inbreeding and apparent selfing rate, produced via mating by proximity through limited pollen dispersal. We used allozyme loci, join-count statistics, and Moran's spatial autocorrelation statistics to separate the spatial genetic structure caused by clonal reproduction from that maintained in sexually reproducing individuals in a population of Lycoris sanguinea var. koreana. Join-count statistics showed that there were statistically significant clustering of clonal genotypes at short distances 2 m. Both the entire population and the set of sexually reproduced individuals exhibited significant spatial autocorrelation on a scale of 2-6 m in an isolation-by-distance manner due to the limited seed and pollen dispersal, which is consistent with a neighborhood size of about 25.

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The 28-chromosome, AABB genome plants were extracted from the common wheat cultivar Chinese Spring by the successive backcross method. The extracted tetraploid plants were cytologically stable in both mitosis and meiosis and resembled normal durum wheat. Their growth, vigor and seed fertility were considerably better than those of previously extracted tetraploids.

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