Zoysia is a warm-season turfgrass, which comprises 11 allotetraploid species (2n = 4x = 40), each possessing different morphological and physiological traits. To characterize the genetic systems of Zoysia plants and to analyse their structural and functional differences in individual species and accessions, we sequenced the genomes of Zoysia species using HiSeq and MiSeq platforms. As a reference sequence of Zoysia species, we generated a high-quality draft sequence of the genome of Z. japonica accession ‘Nagirizaki’ (334 Mb) in which 59,271 protein-coding genes were predicted. In parallel, draft genome sequences of Z. matrella ‘Wakaba’ and Z. pacifica ‘Zanpa’ were also generated for comparative analyses. To investigate the genetic diversity among the Zoysia species, genome sequence reads of three additional accessions, Z. japonica ‘Kyoto’, Z. japonica ‘Miyagi’ and Z. matrella ‘Chiba Fair Green’, were accumulated, and aligned against the reference genome of ‘Nagirizaki’ along with those from ‘Wakaba’ and ‘Zanpa’. As a result, we detected 7,424,163 single-nucleotide polymorphisms and 852,488 short indels among these species. The information obtained in this study will be valuable for basic studies on zoysiagrass evolution and genetics as well as for the breeding of zoysiagrasses, and is made available in the ‘Zoysia Genome Database’ at .

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Tetraploid plants of ruzigrass (Brachiaria ruziziensis) have been obtained by colchicine treatment of in vitro multiple‐shoot clumps and germinated seedlings. Multiple‐shoot clumps were induced and maintained on MS basal medium with 0.5 mg L−1 2,4‐dichlorophenoxyacetic acid (2,4‐D) and 2.0 mg L−1 6‐benzylaminopurine (BAP) according to a previous report. The colchicine treatment consisted of culturing multiple‐shoot clumps on MS basal medium containing 0.0125–0.1% colchicine for 12 and 48 h. Surviving multiple‐shoot clumps were regenerated on MS basal medium containing 2.0 mg L−1 BAP. The ploidy level of plants after colchicine treatment was determined by flow cytometry. Eight tetraploid plants were obtained from multiple‐shoot clumps treated with 0.1% colchicine for 12 h. This treatment was identified as the optimum treatment and resulted in the highest frequency (28.6%) of tetraploid plants among the treatments tested on multiple‐shoot clumps. Five tetraploid plants (31.3%) were obtained when seedlings were treated with 0.1% colchicine for 3 h. Although higher concentrations of colchicine and longer durations of colchicine treatment reduced the survival rate of the explants, such treatments increased the frequency of tetraploid plants. A total of 23 tetraploid plants were obtained from 900 different colchicine‐treated multiple‐shoot clumps, and a total of five tetraploid plants were obtained from 300 colchicine‐treated seedlings. Cytological analysis affirmed the results of flow cytometry. Significant differences in leaf blade stomata were observed between diploid and tetraploid ruzigrass.

The first quantitative trait locus (QTL) analysis of multiple agronomic traits in the model legume Lotus japonicus was performed with a population of recombinant inbred lines derived from Miyakojima MG-20 x Gifu B-129. Thirteen agronomic traits were evaluated in 2004 and 2005: traits of vegetative parts (plant height, stem thickness, leaf length, leaf width, plant regrowth, plant shape, and stem color), flowering traits (flowering time and degree), and pod and seed traits (pod length, pod width, seeds per pod, and seed mass). A total of 40 QTLs were detected that explained 5%-69% of total variation. The QTL that explained the most variation was that for stem color, which was detected in the same region of chromosome 2 in both years. Some QTLs were colocated, especially those for pod and seed traits. Seed mass QTLs were located at 5 locations that mapped to the corresponding genomic positions of equivalent QTLs in soybean, pea, chickpea, and mung bean. This study provides fundamental information for breeding of agronomically important legume crops.