Masako Seki

Distribution of photoperiod-insensitive alleles Ppd-B1a and Ppd-D1a and their effect on heading time in Japanese wheat cultivars

The genotypes of photoperiod response genes Ppd-B1 and Ppd-D1 in Japanese wheat cultivars were determined by a PCR-based method, and heading times were compared among genotypes. Most of the Japanese wheat cultivars, except those from the Hokkaido region, carried the photoperiod-insensitive allele Ppd-D1a, and heading was accelerated 10.3 days compared with the Ppd-D1b genotype. Early cultivars with Ppd-D1a may have been selected to avoid damage from preharvest rain. In the Hokkaido region, Ppd-D1a frequency was lower and heading date was late regardless of Ppd-D1 genotype, suggesting another genetic mechanism for late heading in Hokkaido cultivars. In this study, only 11 cultivars proved to carry Ppd-B1a, and all of them carried another photoperiod-insensitive allele, Ppd-D1a. The Ppd-B1a/Ppd-D1a genotype headed 6.7 days earlier than the Ppd-B1b/Ppd-D1a genotype, indicating a significant effect of Ppd-B1a in the genetic background with Ppd-D1a. Early-maturity breeding in Japan is believed to be accelerated by the introduction of the Ppd-B1a allele into medium-heading cultivars carrying Ppd-D1a. Pedigree analysis showed that Ppd-B1a in three extra-early commercial cultivars was inherited from ‘Shiroboro 21’ by early-heading Chugoku lines bred at the Chugoku Agriculture Experimental Station.

Differences in Cadmium Accumulation and Root Morphology in Seedlings of Japanese Wheat Varieties with Distinctive Grain Cadmium Concentration

Abstract A low cadmium (Cd) concentration in wheat grain is desirable because of Cd toxicity to humans. Grain Cd concentrations in Japanese wheat differed among the varieties in previous study. In this study, we hypothesized that the varieties with a low concentration of Cd in grain have (1) low Cd uptake from the soil through the roots during early growth and/or (2) low Cd translocation from the roots to shoots, and also, that (3) Cd uptake from soil is affected by root morphology. These hypotheses were verified by investigating the concentration and quantity of Cd in root, shoot and leaf tissues, and examining the root morphology of young seedlings of wheat varieties with high and low grain Cd concentrations. Seedlings of ‘Kitahonami’ and ‘Nanbukomugi’ which had low grain Cd concentration (low Cd/G varieties) had a lower Cd quantity in whole plant tissues than ‘Nishikazekomugi’ and ‘Kitakamikomugi’ which had high grain Cd concentration (high Cd/G varieties) during early growth. Low Cd/G varieties also showed lower root to shoot (aerial parts) translocation of Cd than high Cd/G varieties. Seedlings of low Cd/G varieties showed less root branching than high Cd/G varieties. Root frequency showed a significant positive correlation with Cd quantity in whole plant tissues. These results suggest that low Cd/G varieties used in this study have low Cd uptake and translocation from the roots to shoots during early growth, and furthermore, that low Cd uptake at the seedling stage may relate to slow and/or limited development of branching roots.

Isolation of a wheat (Triticum aestivum L.) mutant in ABA 8′-hydroxylase gene: effect of reduced ABA catabolism on germination inhibition under field condition

Pre-harvest sprouting, the germination of mature seeds on the mother plant under moist condition, is a serious problem in cereals. To investigate the effect of reduced abscisic acid (ABA) catabolism on germination in hexaploid wheat (Triticum aestivum L.), we cloned the wheat ABA 8′-hydroxyase gene which was highly expressed during seed development (TaABA8′OH1) and screened for mutations that lead to reduced ABA catabolism. In a screen for natural variation, one insertion mutation in exon 5 of TaABA8′OH1 on the D genome (TaABA8′OH1-D) was identified in Japanese cultivars including ‘Tamaizumi’. However, a single mutation in TaABA8′OH1-D had no clear effect on germination inhibition in double haploid lines. In a screen for a mutation, one deletion mutant lacking the entire TaABA8′OH1 on the A genome (TaABA8′OH1-A), TM1833, was identified from gamma-ray irradiation lines of ‘Tamaizumi’. TM1833 (a double mutant in TaABA8′OH1-A and TaABA8′OH1-D) showed lower TaABA8′OH1 expression, higher ABA content in embryos during seed development under field condition and lower germination than those in ‘Tamaizumi’ (a single mutant in TaABA8′OH1-D). These results indicate that reduced ABA catabolism through mutations in TaABA8′OH1 may be effective in germination inhibition in field-grown wheat.

Cadmium Concentration in Grains of Japanese Wheat Cultivars : Genotypic Difference and Relationship with Agronomic Characteristics

The contamination of cadmium (Cd) into the food chain can be harmful because Cd causes chronic health problems. To evaluate the breeding potential reducing the Cd concentration in wheat grain, we compared Cd concentrations in 237 wheat genotypes including Japanese landraces, Japanese cultivars and introduced alien cultivars for breeding using grain samples collected from upland fields in 2004−5 and 2005−6 growing seasons. The Cd concentration in wheat grain significantly varied with the growing seasons and with the experimental fields. Cultivars bred in northern Japan, including the recent Japanese leading cultivar ‘Hokushin’, tended to have a low Cd concentration in grain compared with that bred in central and southern Japan. Simple correlation analysis between Cd concentration in grain and agronomic characteristics revealed that the Cd concentration in grain showed significant negative correlations with stem number, culm length and spikelet number per spike, and showed significant positive correlation with SPAD value (chlorophyll content) of flag leaf. Stepwise multipleregression analysis showed that the genotypic variation of Cd concentration in grain was associated with the culm length and spiklet number per spike. This study clarified the geographical pattern of genotypes with different Cd concentrations in grain in Japanese wheat cultivars. Cultivars originating from northern Japan may be useful genetic resources to develop cultivars with a low Cd concentration in grain to be grown in the areas where Cd accumulation in wheat grain is a problem.

Molecular and genealogical analysis of grain dormancy in Japanese wheat varieties, with specific focus on MOTHER OF FT AND TFL1 on chromosome 3A.

In the wheat (Triticum aestivum L.) cultivar ‘Zenkoujikomugi’, a single nucleotide polymorphism (SNP) in the promoter of MOTHER OF FT AND TFL1 on chromosome 3A (MFT-3A) causes an increase in the level of gene expression, resulting in strong grain dormancy. We used a DNA marker to detect the ‘Zenkoujikomugi’-type (Zen-type) SNP and examined the genotype of MFT-3A in Japanese wheat varieties, and we found that 169 of 324 varieties carry the Zen-type SNP. In Japanese commercial varieties, the frequency of the Zen-type SNP was remarkably high in the southern part of Japan, but low in the northern part. To examine the relationship between MFT-3A genotype and grain dormancy, we performed a germination assay in three wheat-growing seasons. On average, the varieties carrying the Zen-type SNP showed stronger grain dormancy than the varieties carrying the non-Zen-type SNP. Among commercial cultivars, ‘Iwainodaichi’ (Kyushu), ‘Junreikomugi’ (Kinki-Chugoku-Shikoku), ‘Kinuhime’ (Kanto-Tokai), ‘Nebarigoshi’ (Tohoku-Hokuriku), and ‘Kitamoe’ (Hokkaido) showed the strongest grain dormancy in each geographical group, and all these varieties, except for ‘Kitamoe’, were found to carry the Zen-type SNP. In recent years, the number of varieties carrying the Zen-type SNP has increased in the Tohoku-Hokuriku region, but not in the Hokkaido region.

Distribution of photoperiod-insensitive allele Ppd-A1a and its effect on heading time in Japanese wheat cultivars

The Ppd-A1 genotype of 240 Japanese wheat cultivars and 40 foreign cultivars was determined using a PCR-based method. Among Japanese cultivars, only 12 cultivars, all of which were Hokkaido winter wheat, carried the Ppd-A1a allele, while this allele was not found in Hokkaido spring wheat cultivars or Tohoku-Kyushu cultivars. Cultivars with a photoperiod-insensitive allele headed 6.9–9.8 days earlier in Kanto and 2.5 days earlier in Hokkaido than photoperiod-sensitive cultivars. The lower effect of photoperiod-insensitive alleles observed in Hokkaido could be due to the longer day-length at the spike formation stage compared with that in Kanto. Pedigree analysis showed that ‘Purple Straw’ and ‘Tohoku 118’ were donors of Ppd-A1a and Ppd-D1a in Hokkaido wheat cultivars, respectively. Wheat cultivars recently developed in Hokkaido carry photoperiod-insensitive alleles at a high frequency. For efficient utilization of Ppd-1 alleles in the Hokkaido wheat-breeding program, the effect of Ppd-1 on growth pattern and grain yield should be investigated. Ppd-A1a may be useful as a unique gene source for fine tuning the heading time in the Tohoku-Kyushu region since the effect of Ppd-A1a on photoperiod insensitivity appears to differ from the effect of Ppd-B1a and Ppd-D1a.

Effect of Growing Environment of Soft Wheats on Amylose Content and Its Relationship with Cookie and Sponge Cake Quality and Solvent Retention Capacity

ABSTRACT The effect of growing environments of soft wheat on amylose content and its relationship with baking quality and solvent retention capacities (SRC) was investigated. Near-isogenic soft wheat lines of Norin 61 differing in granule-bound starch synthase (Wx protein) activity and grown in three different regions of Japan: Hokkaido (spring-sown) for 2006 and 2007, Kanto (autumn-sown), and Kyushu (autumn-sown) for 2007 were evaluated. Spring-sown samples produced grains of greater protein content (10.9–12.4%) than autumn-sown samples (7.3–9.1%). In contrast, spring-sown samples of 2007 with higher maturing temperature had lower amylose content (25.5% for Norin 61) compare to the autumn-sown and spring-sown samples of 2006 (27.6–28.4% for Norin 61). Amylose content was strongly correlated to sugar snap cookie (SSCD) diameter (r = 0.957–0.961; n = 10, all samples; P ≤ 0.001, r = 0.701–0.976; n = 7 partial waxy and nonwaxy samples; and Japanese sponge cake (JSCV) volume r = 0.971–0.993; n = 10; P≤ 0.001,...

Growth and yield properties of near-isogenic wheat lines carrying different photoperiodic response genes

Abstract Near-isogenic lines (NILs), carrying different combinations of Ppd-1 genes in the genetic background of an early-maturity cultivar Abukumawase were grown at two sites for two years to elucidate the effects of photoperiodic response genes on the growth and yield of early-maturity wheat ( Triticum aestivum L.) in central and southwestern Japan. Photoperiod-insensitive genes, Ppd-B1a and Ppd-D1a , accelerated young spike development, and this effect was predominant with Ppd-B1 with no additive effect among them. Ppd-B1a and Ppd-D1a also advanced the jointing stage, heading, and maturity, and the effect of Ppd-B1a on the jointing stage and heading was stronger than that of Ppd-D1a. An additive effect of two genes was detected for heading. Besides, Ppd-B1a and Ppd-D1a reduced culm length and grain weight, although the reduction effect on grain weight was not significant. Meanwhile, the mean temperature from double ridge formation stage to heading was lower in NILs with photoperiod-insensitive genes than in NILs with photoperiod-sensitive gene, and there was a significant correlation between mean temperature from double ridge formation stage to terminal spikelet formation stage and spikelet number per spike as well as between mean temperature from terminal spikelet formation stage to heading and grain number per spikelet. Therefore in a genetic background of extremely early-maturity line of spring type wheat, photoperiod-insensitive genes accelerated wheat growth and reduced spikelet numbers in central and southwestern Japan, and the effect of Ppd-B1a was stronger than that of Ppd-D1a.

“Haneumamochi”, a six-rowed hulled barley cultivar with a new waxy allele

オオムギは水田輪作などの作付体系で重要な位置づけ となる冬作物のひとつで,さらに自給率向上を目指して オオムギの国内生産量の増加が求められている.六条皮 麦は主食用オオムギの主な原料で,国内作付面積の 60% 以上を北陸・東北地域で占めており(2016年産,農林水 産省作物統計),寒冷地のオオムギ作が主食用オオムギの 安定供給に果たす役割は大きい.オオムギは食物繊維が 豊富に含まれ,近年その機能性が注目されている.特に 細胞壁多糖の一種である(1,3;1,4)-β-Dグルカン(以下, β-グルカン)の機能性は世界的に関心が高く,米国や EU 諸国などでは健康強調表示が認可されている(青江 2015).国内においても,オオムギの β-グルカンが内臓脂 肪面積や体格指数(BMI),体重,腹囲を減少させること や食後血糖値の上昇抑制,血糖日内変動幅の減少に対し ての効果があることが報告され(Aoe et al. 2017,柳澤 2017),オオムギの機能性についてマスメディアに取り上 げられる機会も増えたことから,押し麦などの炊飯用オ オムギ製品の消費量が増加傾向にある. 従来,主食用オオムギのほとんどがうるち性品種で占 められてきた.もち性オオムギ品種については,主に西 日本で在来品種が作付けされていたが,1980年代頃から 地域特産品として利用され始め,栽培性を改良した「ダ イシモチ」(土井ら 1999)が育成された.その後「セツ