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Genetic relatedness and diversity of 62 cultivars and breeding lines of tetraploid Italian ryegrass (Lolium multiflorum Lam.; 39 accessions) and its interspecific hybrids, Festulolium (18 accessions), and hybrid ryegrass (Lolium × hybridum Hausskn.; 5 accessions), mainly from Japan, were revealed based on 2,824 genome‐wide allele frequencies obtained by the genotyping by random amplicon sequencing‐direct (GRAS‐Di) method using bulk genomic DNA testing. Genomic composition of each accession was estimated according to the occurrence of 77,373 unique GRAS‐Di sequences in the reference population consisting of diploid Italian ryegrass, meadow fescue (Festuca pratensis Huds.), and perennial ryegrass (Lolium perenne L.). The high correlation coefficient (0.98) between the fescue‐specific reads ratio and the previously obtained f‐ratio of genomic in situ hybridization in Festulolium cultivars suggests the usefulness of this simple method. Both cluster analysis based on Nei's standard genetic distance (DST) and principal component analysis (PCA) showed that groups were formed largely by species. However, the complex heritage of Lolium‐Festuca (Festulolium) materials could not be determined by species registration or breeding history alone. Some Festulolium accessions were closely related to Italian ryegrass, whereas some defined as Italian ryegrass may actually be interspecific hybrids. The high genetic diversity of Festulolium compared to Italian ryegrass and hybrid ryegrass revealed by PCA seems due to the wide range of fescue‐specific read ratios (0.04–33.0%). Tetraploid Italian ryegrass did not show clear structural differentiation, but some genetic relationships attributable to breeding history were demonstrated. Mean pairwise DST of tetraploid Italian ryegrass cultivars was significantly lower than that of diploids. Tetraploids and diploids could be separated by PCA plot. Although mean expected heterozygosities of tetraploid and diploid cultivars were not significantly different, the results suggest that the utilization of diploid genetic resources is effective in maintaining and increasing the genetic diversity of breeding populations of tetraploid Italian ryegrass. [ABSTRACT FROM AUTHOR]

We are developing low noise analog ASICs for hard X-ray and gamma-ray astronomy. They are based on a sub-micron CMOS process. Our design includes a finely-adjustable high-resistance circuit, which, for example, enables us to realize a pole-zero-cancellation in the analog chain. A two-dimensional ASIC with a fast read-out scheme and a one-dimensional ASIC with an improved analog design are developed and verified. With the latter ASIC connected with a CdTe detector, we have obtained a radioactive source spectrum with an energy resolution of 4.6 keV (FWHM) at 59.5 keV. Index Terms--ASIC, CdTe, gamma-ray, X-ray.

To reveal the genetic diversity and structure of cultivars and breeding materials of diploid Italian ryegrass (Lolium multiflorum Lam.) in Japan, using genome‐wide allele frequency data obtained by genotyping by random amplicon sequencing, direct of pooled DNA, we investigated genetic diversity among and within 89 accessions. We selected 2629 reliable alleles at 456 polymorphic loci to evaluate allele frequency in each accession. Results of hierarchical cluster analysis based on Nei's standard genetic distance and of principal component analysis and nonhierarchical cluster analysis based on the complete set of allele frequencies classified the accessions into a large group including major Japanese cultivars and their ancestral landraces with a wide range of maturity, and a small group with mainly medium maturity, including 'Gulf', introduced from overseas. The genetic relationships fully reflected the kinship inferred from the breeding history in Japan. Mean expected heterozygosity (HE) and number of alleles per locus (A) were evaluated as indices of genetic diversity within each accession. We found a significant negative correlation between the year of application for varietal registration and HE or A in 14 early‐maturing Japanese cultivars. The genetic diversity profile can be used for breeding to maintain or increase the diversity within cultivars or breeding materials. [ABSTRACT FROM AUTHOR]

In this study, to breed endophyte (Epichloë uncinata)‐infected festololium (x Festulolium Aschers.et Graebn.), we backcrossed endophyte‐infected Italian ryegrass (Lolium multiflorum Lam.) to festulolium. To prevent self‐pollinated plants being mixed with the progeny, we used polymerase chain reaction (PCR)‐based DNA marker sets distinguishing between Lolium and Festuca species. In the first backcrossing (F1 development), 20 of the 21 progeny plants showed Festuca‐specific band patterns and were endophyte‐infected. We developed six maternal lines (BC1 development) by backcrossing six selected F1 plants. More than 97% of plants from five maternal lines had novel Festuca‐specific band patterns which their maternal parents lacked. However, only 54% plants of the maternal line F1–18 exhibited novel Festuca‐specific band patterns. F1–18 showed Festuca‐specific band patterns with almost all tested DNA marker sets, and its f ratio (the ratio of Festuca‐specific region to the whole genome) was 31.1%, indicating that F1–18 had an almost complete set of the Festuca genome. Because paternal backcrossing festulolium parents were amphidiploids, an f ratio of approximately 25% corresponds to a complete set of the Festuca genome. We found that it was difficult to evaluate BC2 hybridity using the same DNA marker sets because very few DNA markers were distinctive. In total, we bred and selected at least 146 true BC1 hybrids and endophyte‐infected plants using DNA markers. [ABSTRACT FROM AUTHOR]