Hironori Katayama

Peace, a MYB-like transcription factor, regulates petal pigmentation in flowering peach ‘Genpei’ bearing variegated and fully pigmented flowers

Summary Peace expression determined flower colouration whether pigmented or variegated. In spite of the close relationship between Peace and AtMYB123, a proanthocyanidin regulator, Peace regulates anthocyanin biosynthesis in flowering peach.

Genetic structure of East Asian cultivated pears (Pyrus spp.) and their reclassification in accordance with the nomenclature of cultivated plants

By use of Bayesian statistical inference and allelic data for 18 microsatellite loci, we analyzed the genetic structure of Chinese, Korean, and Japanese pear cultivars and of native populations of Pyrus ussuriensis. Although Japanese pear cultivars had a simple genetic structure, Chinese and Korean pear cultivars were admixures of Japanese pear and native P. ussuriensis from the Asian continent. Genetic differentiation between groups of native populations and those of cultivars was high, but cultivars were not well differentiated from each other. Chinese and Korean cultivars, which have traditionally been classified as either P. ussuriensis, P. bretschneideri, or P. pyrifolia, were much closer to Japanese cultivars, which have traditionally been classified as P. pyrifolia, than to native P. ussuriensis. We propose a new classification of cultivars by using the Group concept in accordance with the International Nomenclature for Cultivated Plants, namely, the Pyrus Ussurian pear group, the Pyrus Chinese white pear group, the Pyrus Chinese sand pear group, and the Pyrus Japanese pear group.

Sequence comparison of the 5' flanking regions of Japanese pear (Pyrus pyrifolia) S-RNases associated with gametophytic self-incompatibility

Abstract Genomic clones of 2.8 kb, 4.3 kb and 6.5 kb for the S2-, S3- and S5-RNases of Japanese pear(Pyrus pyrifolia), respectively, were isolated and sequenced. Comparison of the 5’-flanking regions of these genes with the same region of the S4-RNase gene indicated that a highly similar region of approximately 200 bp exists in the regions just upstream of the putative TATA boxes of the four Japanese pear S-RNase genes. This suggests the presence of cis-regulatory element(s) in this region.

Diversity of odor-active compounds from local cultivars and wild accessions of Iwateyamanashi (Pyrus ussuriensis var. aromatica) revealed by Aroma Extract Dilution Analysis (AEDA)

Some local cultivars and wilds of Iwateyamanashi (Pyrus ussuriensis var. aromatica) that grows wild in Northern Tohoku, Japan have good aromatic fruit. Iwateyamanashi may be valuable germplasms as a donor of odor compounds in breeding of Japanese pear (Pyrus pyrifolia), because almost all Japanese pear cultivars have faint odor. Fruits odors from a local cultivar ‘Sanenashi’, a wild accession (i0830) in Iwateyamanashi, cultivars of ‘Kosui’ and ‘La France’ were characterized at first with comparative Aroma Extract Dilution Analysis (AEDA). Application of AEDA, based on Gas chromatography/Olfactometry analysis (GC/O), on the odor concentration prepared from ‘Sanenashi’ indicated the presence of 33 odor-active compounds including methyl and ethyl esters, aldehydes and alcohol. The eleven odor compounds from 16 accessions of Iwateyamanashi showed various combinations and wide range of odor concentrations by Principal Component Analysis (PCA). Especially 2 accessions of local cultivar ‘Natsunashi’ plotted in the highly ethyl ester group might be useful for Japanese pear breeding.

Population Structure of and Conservation Strategies for Wild Pyrus ussuriensis Maxim. in China.

Pyrus ussriensis Maxim. is native to the northern part of China, but whose habitats are currently being destroyed by environmental changes and human deforestation. An investigation of population structure and genetic diversity of wild Ussurian pear is a priority in order to acquire fundamental knowledge for conservation. A total of 153 individuals of wild Ussurian pear from the main habitats, Heilongjiang, Jilin, and Inner Mongolia in China, possessed low genetic diversity as a result of habitat fragmentation. The genetic diversity of the populations in Inner Mongolia and north east of Heilongjiang was especially low and there was the possibility of inbreeding. Wild Ussurian pears were divided into 5 groups based on the Bayesian clustering method using 20 nuclear SSRs (nSSRs) and 5 groups by haplotype distributions using 16 chloroplast SSRs (cpSSRs), and the populations in Inner Mongolia and north east of Heilongjiang represented unique genotypes. AMOVA indicated there was a 20.05% variation in nSSRs and a 44.40% variation in cpSSRs among populations. These values are relatively high when compared to those of other tree species. Haplotype E, positioned in the center of the cpSSR analysis network and showed the largest number of connections with other haplotypes, represented the most important haplotype. Inner Mongolia and the north east of Heilongjiang are two areas that need urgent conservation because of their genetic vulnerability and peculiarity. We determined 4 conservation units based on the clustering by nSSRs and cpSSRs, and geographic factor. This information is helpful in deciding the conservation strategies for wild Ussurian pear in China.

Introgression and Long-Term Naturalization of Archaeophytes into Native Plants - Underestimated Risk of Hybrids

Alien plants pose problems in the conservation of biodiversity, especially by invasion and successive mal-effects on local ecosystem and biodiversity (Pysek et al., 1995; Ellstrand, 2003; Nentwig, 2007). Even if they are only in cultivation, they could affect by hybridization, vector of diseases and pests and other factors. Since an alien plant is defined as one whose distribution has expanded out of its native range under human influence, the history of alien plants begins with human migration, especially in association with agriculture. As most have spread with active migration since the Age of Discovery, alien plants can be delineated into archaeophytes (introduced before the Age of Discovery) and neophytes (introduced since) (Pysek et al., 2002; Preston et al., 2004).

Genetic structure and diversity of the wild Ussurian pear in East Asia.

The Ussurian pear is the most important cultivated pear in the northern part of China. Cultivated Ussurian pears are considered to have derived from Pyrus ussuriensis Maxim. which is native to the northeast of China. In Japan, two varieties of P. ussuriensis, P. ussuriensis var. aromatica and var. hondoensis are native to the northern area and the central area of the main island respectively. In order to reveal the origin of Pyrus ussuriensis var. aromatica distributed in the northern area of main island of Japan, more than 40 explorations have been performed in Japan and in China, and more than 30 natural habitats were recognized. These natural habitats are at risk of extinction because of human development and forest degradation caused by climate change. Population structure and genetic diversity of P. ussuriensis in China and P. ussuriensis var. aromatica in Japan have been investigated using both morphological and molecular markers in order to define appropriate conservation units, and to provide a good focus for conservation management. Distant evolutionary relationships between P. ussuriensis Maxim. in China and P. ussuriensis var. aromatica in Japan inferred from population genetic structure and phylogenetic analysis are also discussed.