Miyuki Nitta

Asian PERILLA Crops and Their Weedy Forms: Their Cultivation, Utilization and Genetic Relationships

The cultivation and utilization of two Perilla crops were surveyed in Asia. Perilla frutescens var. frutescens is essentially an oil crop and is now widely cultivated in China and Korea. Its seeds are also used as a flavor for traditional foods in Japan, Korea, China and Nepal. In Korea, leaves of var. frutescens are used as a fresh vegetable and for making pickles. Whereas P. frutescens var. crispa is a Chinese medicine and afresh vegetable in the Far East, it has almost disappeared in many parts of Asia. Cultivation of var. crispa is still continued in Japan and Vietnam. In particular, it is cultivated in a large scale for coloring pickles in the areas where a large amount of plum pickles are produced in Japan. In China and Korea, it remains only as a relict form. Weedy plants ofPerilla are found in Japan, Korea and China. We can classify them into two forms; one, which is closely related to var. frutescens, and the other, which is similar to var. crispa We foundP citriodora andR hirtella in Guandong and Jiangxi provinces of China, respectively. It is clear that they are not endemic to Japan. A phylogenetic tree of samples of two Perilla crops and their weedy forms based on RAPD markers revealed that the weedy forms similar to var. crispa and var. frutescens are genetically closely related to var. crispa and var. frutescens, respectively. Var. crispa and its closely related weedy form seem to be more primitive.

Novel QTLs for growth angle of seminal roots in wheat (Triticum aestivum L.)

AimsBecause plants cannot change their environmental circumstances by changing their location, they must instead adapt to a wide variety of environmental conditions, especially soil conditions. One of the most effective ways for a plant to adapt to a given soil condition is by modifying its root system architecture. We aim to identify the genetic factors controlling root growth angle, a trait that affects root system architecture.MethodsThe present study consisted of a genetic analysis of the seminal root growth angle in wheat; the parental varieties of the doubled haploid lines (DHLs) used in this study exhibited significantly different root growth directions. Using the ‘basket’ method, the ratio of deep roots (DRR; the proportion of total roots with GA > 45 degrees) was observed for evaluating deep rooting.ResultsWe were able to identify novel quantitative trait loci (QTLs) controlling the gravitropic and hydrotropic responses of wheat roots. Moreover, we detected one QTL for seminal root number per seedling (RN) on chromosome 5A and two QTLs for seminal root elongation rate (ER) on chromosomes 5D and 7D.ConclusionsGravitropic and hydrotropic responses of wheat roots, which play a significant role in establishing root system architecture, are controlled by independent genetic factors.

Genetic basis for spontaneous hybrid genome doubling during allopolyploid speciation of common wheat shown by natural variation analyses of the paternal species.

The complex process of allopolyploid speciation includes various mechanisms ranging from species crosses and hybrid genome doubling to genome alterations and the establishment of new allopolyploids as persisting natural entities. Currently, little is known about the genetic mechanisms that underlie hybrid genome doubling, despite the fact that natural allopolyploid formation is highly dependent on this phenomenon. We examined the genetic basis for the spontaneous genome doubling of triploid F1 hybrids between the direct ancestors of allohexaploid common wheat (Triticum aestivum L., AABBDD genome), namely Triticum turgidum L. (AABB genome) and Aegilops tauschii Coss. (DD genome). An Ae. tauschii intraspecific lineage that is closely related to the D genome of common wheat was identified by population-based analysis. Two representative accessions, one that produces a high-genome-doubling-frequency hybrid when crossed with a T . turgidum cultivar and the other that produces a low-genome-doubling-frequency hybrid with the same cultivar, were chosen from that lineage for further analyses. A series of investigations including fertility analysis, immunostaining, and quantitative trait locus (QTL) analysis showed that (1) production of functional unreduced gametes through nonreductional meiosis is an early step key to successful hybrid genome doubling, (2) first division restitution is one of the cytological mechanisms that cause meiotic nonreduction during the production of functional male unreduced gametes, and (3) six QTLs in the Ae . tauschii genome, most of which likely regulate nonreductional meiosis and its subsequent gamete production processes, are involved in hybrid genome doubling. Interlineage comparisons of Ae . tauschii ’s ability to cause hybrid genome doubling suggested an evolutionary model for the natural variation pattern of the trait in which non-deleterious mutations in six QTLs may have important roles. The findings of this study demonstrated that the genetic mechanisms for hybrid genome doubling could be studied based on the intrinsic natural variation that exists in the parental species.

The Distribution of Perilla Species

Perilla (Lamiaceae) contains one tetraploid species, P. frutescens (L.) Britt. and three diploid species, P. citriodora (Makino) Nakai, P. hirtella Nakai and P. setoyensis G. Honda. Tetraploid species have been traditionally cultivated in Asia for their seed oil and for their fragrant leaves that are used as medicine or as a garnish for fish. The center of diversity is still obscure. To conserve the genetic resources, it is important to know the diversity of the tetraploid species. The three diploid species, which are possible parents of the tetraploid species, are all believed to be indigenous to Japan. Their distribution in China and Korea was clarified on the basis of herbarium and field surveys. The tetraploid species is assumed to have originated somewhere around the mid-to downstream area of the Changjiang River. Though Perilla is not cultivated as often in these areas as in northern China, Korea, the Himalayan region, or Myanmar, these areas should also be important for the conservation of genetic resources of tetraploid Perilla crops because of the expected high genetic diversity.

Molecular Genetic Analysis of Domestication Traits in Emmer Wheat. I: Map Construction and QTL Analysis using an F2 Pupulation

ABSTRACT Emmer wheat (Triticum turgidum ssp. dicoccum) was a principal crop in the development and spread of Neolithic agriculture in the Old World. It represents the primitive situation in the domestication of AABB tetraploid wheat. To understand the genetic modifications underlying the early stage of tetraploid wheat domestication, QTL analysis was carried out using 144 F2 plants derived from a cross between the domesticated emmer wheat and the wild emmer wheat (T. turgidum ssp. dicoccoides). To our knowledge, this is the first report of molecular linkage map and QTL analysis of the domestication-related characters in emmer wheat. The linkage map with a total length of 2849.8 cM was constructed using 227 microsatellite (SSR) markers. Chromosomal location and effect of QTLs were estimated for ten domestication-related traits including whole plant and spike characteristics. Seventeen QTLs were detected on chromosomes 1B, 2A, 2B, 3A, 3B, 4A, 5B, and 7B. Two regions on chromosomes 2A and 3B have a large effect on rachis fragility. The estimated locations of these QTLs corresponded to those of the Br genes identified in the previous studies on a more adapted durum wheat (T. turgidum ssp. turgidum conv. durum). Our results indicate that selection and conversion of at least two Br loci (on chromosomes 2A and 3B) occurred during the domestication of emmer wheat prior to appearance of free-threshing wheat (e.g. durum). The map positions of nine QTLs for the traits related to seed production overlapped in two regions on chromosomes 2A and 5B. The result suggests that these chromosomal regions played an important role in increasing seed production during the domestication of emmer wheat.

Diversification of Multipurpose Plant, Perilla Frutescens

The traditional Asian crop, Perilla frutescens has multiple uses. There are specialized cultivars for seed oil and for medicinal use, as well as wild/weedy forms growing in various habitats. Based on selective characteristics of leaf odor, anthocyanin pigmentation, seed hardness and seed diameter, the diversity of this species was investigated to clarify the intraspecific differentiation. P. frutescens was divided into five groups by the combination of three qualitative characteristics: leaf odor, anthocyanin pigmentation and seed hardness. Most of the plants cultivated for oil belonged to one group, while medicinal plants belonged to three other groups. Wild/weedy forms were in the last group. The five groups could not be distinguished by seed diameter. Though the plants cultivated for oil tended to have larger seeds than the medicinal and wild/weedy plants, there was no boundary either between the two crops, or among various phenotypes of P. frutescens.

Differential contribution of two Ppd-1 homoeoalleles to early-flowering phenotype in Nepalese and Japanese varieties of common wheat

Wheat landraces carry abundant genetic variation in heading and flowering times. Here, we studied flowering-related traits of two Nepalese varieties, KU-4770 and KU-180 and a Japanese wheat cultivar, Shiroganekomugi (SGK). These three wheat varieties showed similar flowering time in a common garden experiment. In total, five significant quantitative trait loci (QTLs) for three examined traits, the heading, flowering and maturation times, were detected using an F2 population of SGK/KU-4770. The QTLs were found at the Ppd-1 loci on chromosomes 2B and 2D and the 2B QTL was also confirmed in another F2 population of SGK/KU-180. The Ppd-D1 allele from SGK and the Ppd-B1 alleles from the two Nepalese varieties might be causal for early-flowering phenotype. The SGK Ppd-D1 allele contained a 2-kb deletion in the 5′ upstream region, indicating a photoperiod-insensitive Ppd-D1a allele. Real-time PCR analysis estimating the Ppd-B1 copy number revealed that the two Nepalese varieties included two intact Ppd-B1 copies, putatively resulting in photoperiod insensitivity and an early-flowering phenotype. The two photoperiod-insensitive Ppd-1 homoeoalleles could independently contribute to segregation of early-flowering individuals in the two F2 populations. Therefore, wheat landraces are genetic resources for discovery of alleles useful for improving wheat heading or flowering times.