Hiroyoshi Iwata

Quantitative evaluation of the shapes of biological organs is often required in various research fields, such as agronomy, medicine, genetics, ecology, and taxonomy. Elliptic Fourier descriptors (EFDs), proposed by Kuhl and Giardina (1982), can delineate any type of shape with a closed two-dimensional contour and have been effectively applied to the evaluation of various biological shapes in animals (Bierbaum and Ferson 1986; Diaz et al. 1989; Ferson et al. 1985; Rohlf and Archie 1984) and plant

Genomics-assisted breeding methods have been rapidly developed with novel technologies such as next-generation sequencing, genomic selection and genome-wide association study. However, phenotyping is still time consuming and is a serious bottleneck in genomics-assisted breeding. In this study, we established a high-throughput phenotyping system for sorghum plant height and its response to nitrogen availability; this system relies on the use of unmanned aerial vehicle (UAV) remote sensing with ei

High-throughput assay of molecular markers enables to utilize large amounts of markers in linkage mapping. To incorporate numerous markers into a linkage map, the development of a highly efficient method for linkage mapping is indispensable. When the number of loci is large, locus ordering is a major difficulty in linkage mapping, since the number of possible orders becomes very large. To address this problem, we developed a new algorithm for locus ordering and used it in a newly developed compu

Recent advancements in genomic analysis technologies have opened up new avenues to promote the efficiency of plant breeding. Novel genomics-based approaches for plant breeding and genetics research, such as genome-wide association studies (GWAS) and genomic selection (GS), are useful, especially in fruit tree breeding. The breeding of fruit trees is hindered by their long generation time, large plant size, long juvenile phase, and the necessity to wait for the physiological maturity of the plant

Difficulty in detecting rare variants is one of the problems in conventional genome-wide association studies (GWAS). The problem is closely related to the complex gene compositions comprising multiple alleles, such as haplotypes. Several single nucleotide polymorphism (SNP) set approaches have been proposed to solve this problem. These methods, however, have been rarely discussed in connection with haplotypes. In this study, we developed a novel SNP-set method named "RAINBOW" and applied the met

We conducted a comparison of 10 existing regression methods and 3 new ranking methods on 6 datasets, consisting of 4 plant species and 25 traits. Our experimental results suggest that tree-based ensemble methods including McRank, Random Forests and Gradient Boosting Regression Trees achieve excellent ranking accuracy. RKHS regression and RankSVM also achieve good accuracy when used with an RBF kernel. Traditional regression methods such as Bayesian lasso, wBSR and BayesC were found less suitable

Although the potential of marker-assisted selection (MAS) in fruit tree breeding has been reported, bi-parental QTL mapping before MAS has hindered the introduction of MAS to fruit tree breeding programs. Genome-wide association studies (GWAS) are an alternative to bi-parental QTL mapping in long-lived perennials. Selection based on genomic predictions of breeding values (genomic selection: GS) is another alternative for MAS. This study examined the potential of GWAS and GS in pear breeding with

We performed whole-genome Illumina resequencing of 198 accessions to examine the genetic diversity and facilitate the use of soybean genetic resources and identified 10 million single nucleotide polymorphisms and 2.8 million small indels. Furthermore, PacBio resequencing of 10 accessions was performed, and a total of 2,033 structure variants were identified. Genetic diversity and structure analysis congregated the 198 accessions into three subgroups (Primitive, World, and Japan) and showed the p

The aim of this study was to compare the accuracy of genomic selection (i.e., selection based on genome‐wide markers) to phenotypic selection through simulations based on real barley ( Hordeum vulgare L.) single nucleotide polymorphism (SNP) data (1325 SNPs by 863 breeding lines). We simulated 100 quantitative trait loci (QTL) at randomly picked SNPs, which were dropped from the marker data. The sum of heritability of all the QTL was set as 0.1, 0.2, 0.4, or 0.6. We generated 100 datasets for ea

We assessed the genetic diversity in Japanese indigenous common buckwheat (Fagopyrum esculentum) cultivars using amplified fragment length polymorphism (AFLP) and simple sequence repeat (SSR) markers and investigated the relationships between the genetic diversity and agronomic traits. The average expected intracultivar hetero zygosity was 0.303 for AFLP and 0.819 for SSR. The differentiations among agroecotypes, among cultivars within an agroecotype, and among cultivars were small (0.002, 0.024

Profiling elemental contents in wheat grains and clarifying the underlying genetic systems are important for the breeding of biofortified crops. Our objective was to evaluate the genetic potential of 269 Afghan wheat landraces for increasing elemental contents in wheat cultivars. The contents of three major (Mg, K, and P) and three minor (Mn, Fe, and Zn) elements in wheat grains were measured by energy dispersive X-ray fluorescence spectrometry. Large variations in elemental contents were observ

The inheritance of citrus leaf shape was investigated by analyzing a diallel set of crosses of five citrus varieties/selections. Leaf contours were extracted by image processing, and described by elliptic Fourier descriptors. Mathematically independent shape characteristics were then identified by principal component analysis of the descriptors. The 1st, 2nd, 3rd and 4th components accounted for 51%, 20%, 10% and 6% of the total shape variation, and were good measures of the ratio of length to w