In order to breed Brassica napus–Raphanus sativus monosomic addition lines (MALs), hybridizations between two synthetic amphidiploid (RRAA and RRCC) and B. napus (AACC) were performed. Two allooctoploids (RRAAAACC and AACCRRCC) were produced from each F1 hybrid by chromosome doubling. From successive backcrosses to B. napus, MAL plants were first obtained in BC2 generation and the R. sativus-derived chromosome was identified by genomic in situ hybridization (GISH). The nine chromosomes of R-genome in the MAL plants were clearly classified by each chromosome-specific RAPD markers. As a result, alloplasmic (radish cytoplasm) B. napus–R. sativus MAL having 8 types (a–i, except for h-type) and autoplasmic (rape cytoplasm) MAL with complete 9 types (a–i) were obtained in BC3 and BC4 generations. These alloplasmic and autoplasmic MAL plants were showed differences in their morphological, physiological and cytogenetical characters. From the survey of favorable traits, it was suggested that the a-type had fertility restoring gene(s) for male sterility in alloplasmic line and the g-type had a gene controlling white color petal. These two MALs are useful materials for exploring agronomic traits located on each chromosome of radish and for promoting the introgression of promising radish gene(s) to B. napus.
Genetic relationships among 50 Gentiana accessions, comprising 36 wild species and 14 cultivars, were determined based on analysis of sequence data for the chloroplast trnL(UAA) intron, the rpl16 coding region and the rpl16-rpl14 intergenic spacer (IGS), together with nuclear DNA content as determined by flow cytometric analysis. The combined chloroplast DNA (cpDNA) data set was analyzed using both neighbor-joining (NJ) and maximum parsimony (MP) methods. The NJ and the strict consensus trees were generally congruent with previous phylogenetic and taxonomic studies, whereas G. cachemirica and G. yakushimensis were classified in different sectional affinities from their prevailing classifications. Three major cpDNA haplotypes (designated A, B and C), comprising 30 accessions in the sections Pneumonanthe, Cruciata, and Kudoa (ser. Monanthae), were each distinguished by two single-nucleotide polymorphisms in the rpl16-rpl14 IGS and the rpl16 coding region. Nuclear DNA content varied from 6.47 to 11.75 pg among the taxa possessing cpDNA haplotype A. These results provide genetic information that will assist in the development of future Gentiana breeding strategies.
The influences of moisture content of barley (Hordeum vulgare L.) seeds which were presoaked for 13 h and re-dried before irradiation on boron addition effect (BAE) and relative biological effectiveness (RBE) of alpha particles and protons were evaluated. Seeds of normal (10.21% in embryo), low (2.55%) and high (28.0%) moisture content showed different regression of BAE values on the absorbed amount of 10B. The regression coefficient was highest for normal moisture content, followed by low moisture content, and the lowest for high moisture content. RBE of alpha particles also significantly differed between the moisture contents. Seeds of normal, low and high moisture contents showed 46.4, 37.4 and 17.0 of RBE value, respectively. Contrarily, RBE values of protons did not significantly vary with moisture content. It was found that the ratio of RBE of alpha particles between different moisture contents could be expressed by the product of the three ratios, i.e. ratio of sensitivity to gamma-rays, ratio of BAE, and ratio of moisture content. It was concluded that adjustment of moisture of the seeds to normal content (about 10%) is important to get a high value of both BAE and RBE of alpha particles.
Fruit crispness is of great importance in cucumber as well as in other fruit vegetables, because it relates directly to the commercial value of the product. In breeding projects and pre- or postharvest studies of fruit texture, an effective quantification method has been desired to replace rough, qualitative evaluations of fruit texture based solely on human perceptions. We applied several analytical methods to the force–deformation curve to quantify cucumber fruit crispness and assessed the efficacy of these methods as candidate cucumber fruit crispness indicators for use in breeding or research. Texture parameters for the flesh and placenta of 12 cucumber cultivars, based on the crispness index, apparent fractal dimension, and power spectrum and peak analyses, were calculated from mechanical measurement results. There was a significant large genotypic (cultivar) effect on the texture parameter values and a lesser, but still significant, contribution from the environment. Furthermore, we found strong relationships between these texture parameters and sensory crispness. These results indicate that these methods for analyzing the force–deformation curve provide effective, quantitative indicators of fruit crispness, with considerable promise for application in scientific research and breeding programs.
Mungbean (Vigna radiata (L.) Wilczek) has been a mandate crop of AVRDC–The World Vegetable Center (AVRDC) over the past 30 years. Mungbean breeding lines developed by AVRDC were released to farmers in collaborating countries and used as genetic stocks by national programs. Over 6,500 crosses have been made by AVRDC breeding program using mainly 39 parental lines. In the present study, 241 SSRs were employed to assess diversity among the parents and 5 cultivars derived from AVRDC breeding lines. Forty-eight SSRs expressed polymorphism among them. The AVRDC elite parental germplasm possesses a high genetic diversity. In the 39 parental lines, a total of 175 alleles were detected by the polymorphic SSR markers ranging from 2 to 19 alleles per marker and with PIC values ranging from 0.049 to 0.883. The polymorphic SSRs distinguished all the mungbean lines. Grouping the germplasm by UPGMA clustering based on SSR polymorphism was in general agreement with the origins and/or pedigree information. The 5 cultivars selected from AVRDC breeding lines had a moderate genetic diversity. Of the 175 alleles found in 39 parental lines, 69 alleles (39.43%) were present in the 5 cultivars. The cultivars were grouped with the Philippine germplasm and most of them were close to one of the parents in their pedigrees. Based on the results, reduction in gene diversity due to breeding among AVRDC elite parental mungbeans is not high. Yet, the diversity found in this study is relatively high as compared to those from larger collections of cultivated mungbean in the previous studies.
The recent amendment of the Plant Variety Protection Law in Japan has extended plant breeders’ rights to cover the harvested materials and manufactured products from a cultivar. The Government Quality Labeling Standards require proper food labeling, which includes cultivar names if they appear on the product label. To protect the breeder’s right and ensure the proper labeling of wheat products, we have developed simple sequence repeat (SSR) markers from wheat expressed sequence tags (ESTs) to identify the wheat cultivars used in wheat products. From a total of 3,759 SSR sites found in the EST data base, PCR amplification was tested at 186 sites in 14 wheat cultivars. We also confirmed that the markers did not occur in other crops, and so can accurately identify wheat cultivars used in products blended with these crops. A total of 10 SSR sites were finally selected and their capacity to identify 41 Japanese cultivars and 17 USA, Australian, or Canadian cultivars was examined. These SSR markers are sufficient to distinguish the Japanese cultivars from foreign cultivars and to individually identify the major Japanese cultivars, such as Hokushin and Norin 61. The SSR markers can also determine the wheat cultivars used in processed foods.
We investigated the usefulness of ion beams for mutation breeding in rice (Oryza sativa L.) by comparing the efficiency (i.e., the ratio of desirable mutations to plant damage such as lethality and sterility), mutation rate, spectrum, and optimum dose to that of gamma rays. Rice seeds were irradiated with carbon ions (mean linear energy transfer = 76 and 107 keV/μm), helium ions (9 keV/μm), and gamma rays, and their survival and fertility were examined in the M1 generation. The frequency of chlorophyll mutations and their types (albina, xantha, and viridis) were examined in the M2 generation, using the M1-plant progeny method. The efficiency of ion beams either equaled or exceeded that of gamma rays. In addition, the mutation rate of ion beams was higher than that of gamma rays. Thus, ion beams appeared to efficiently induce mutants with little radiation damage. No remarkable difference was observed in the relative frequencies of each type of mutation among 3 types of ion beams and gamma rays, thus suggesting that there was no difference in the spectrum. A shoulder dose, which hardly affected survival, was sufficient to efficiently obtain mutants for both types of radiation.
Asian rice (Oryza sativa L.) cultivars were recently classified into L-type, S-type, and intermediate M-type (rich, poor and middle intermediate-chain) on the basis of the fine structure of amylopectin in their grains. We selected 4 cultivars with M-type amylopectin from 174 local Japanese nonwaxy upland rice cultivars by scoring the disintegration of starch granules in alkaline solution and measuring the pasting temperature (PT) of their rice flours. Analyzed amylopectin fine structure, these cultivars exhibited intermediate characteristics between those of S-type Koshihikari and L-type IRAT109. Moreover, compared hardness of dumpling cakes after cooled for 3 h and 24 h. The hardness was in the order L-type > M-type > S-type, each other. On the other hand, the amylopectin chain ratio (ACR) was negatively correlated with the hardness of dumpling cakes both after cooled for 3 h and 24 h. Therefore, we concluded that the 4 cultivars—Chikanarijyun1, Hokkaiakage, Kairyo13, and Mogamichikanari1—had M-type amylopectin, and Japanese local upland rice has wide genetic diversity about starch mutation.
The relative biological effectiveness (RBE) of alpha particles and protons emitted during exposure of barley (Hordeum vulgare L.) seeds to thermal neutrons were estimated. 10B-enriched re-dried seeds were irradiated with thermal neutrons or gamma-rays. Two assumptions so far believed that boron distribution was uniform throughout either natural dormant seeds or 10B-enriched seeds, and that boron atoms enter the seeds as freely as water molecules do, were found to be invalid. A boron addition effect (BAE) as high as 58.2 was obtained after thermal neutron exposure of seeds presoaked in 4800 μg·g−1 of 10B-enriched boric acid solution. Estimates of RBE of alpha particles were nearly constant and independent of the contents of absorbed 10B. RBE averaged 55.0 and 55.1 for the seed and spike presoaking methods of boron absorption, respectively. We could also obtain RBE of protons as high as 48.7 and 43.9 for the seed and spike methods, respectively. Boron addition converted the principal capture element during thermal neutron exposure from protons in dormant seeds to boron in 10B enriched-seeds.
We studied outcrossing in a rice plant under field conditions over five years, to clarify the relationship between outcrossing, pollen flow, and meteorological factors. We employed two cultivars to discriminate hybrid grains: Okunomurasaki, a non-glutinous cultivar with purple grains, was used as the donor, and Himenomochi, a glutinous cultivar, was used as the recipient. Therefore, we could accurately discriminate hybrid grains by the presence of two phenotypic markers—the xenia grain and the leaf color of the F1 plant. The results indicated that outcrossing occurred when the difference in the heading date between the donor and recipient was 11 days or less. And it did not occur when the difference was 13 days or more. In 2004 and 2007, hybrid grains were detected at a distance of 20 m or more from the donor. The wind speed during the flowering period of the donor was higher in both of these years than during the other three years of the study period. This suggested that outcrossing often occurred when the flowering period of the donor and recipient overlapped and the wind speed was high. In addition, outcrossing was considerably depressed when the difference in the day of heading between the donor and recipient was large.
Clubroot resistance (CR) against the Ano-01 isolate of the clubroot pathogen Plasmodiophora brassicae for individual radish chromosomes was evaluated using 9 types (a–i) of Brassica napus–Raphanus sativus monosomic addition lines (MALs) produced from the progenies of the hybridization of B. napus (2n = 38, AACC) and Raphanobrassica ‘Rb-63’ (2n = 36, RRCC). Among the 9 types of MAL, the c-type showed high resistance, although other types and reverted plants with somatic chromosomes like B. napus (2n = 38) were susceptible. This result suggested that a major CR gene against the Ano-01 isolate may be located on the radish c-chromosome. However, it was also assumed that there might be other CR gene(s) in radish because many c-type MAL plants showed slight disease symptoms.