Root hair is considered to play important roles in water and nutrient uptake and anchoring the plant to the soil. To gain further knowledge of root hair morphogenesis in rice, we isolated root hairless 2 (rth2) mutant from the mutant panel of Nipponbare. Positional cloning and complementation test revealed that the causal gene of rth2 was Cellulose Synthase-Like D1 (OsCSLD1). rth2 has a premature stop codon in exon 1 as a result of two consecutive nucleotide substitutions and is predicted to produce truncated proteins lacking the D, D, D, QxxRW motif and 8 transmembrane domains. In rth2, bulges were normally initiated from asymmetric divisions of root epidermal cells, but bulges did not elongate. Therefore, rth2 shows completely roothairless phenotype. qRT-PCR analysis revealed that OsCSLD1 was expressed not only in root but also in shoot. In situ hybridization showed that OsCSLD1 was expressed not only in root hairs but also in epidermal and cortex cell walls except for stele. Agronomic character evaluation in pot experiments showed that rth2 did not differ significantly from Nipponbare in all characters examined except for root dry weight, which showed a significant increase in rth2. In paddy field experiment, rth2 was significantly inferior compared with Nipponbare in agronomic performance.
Primula sieboldii is a self-incompatible ornamental plant that has been cultivated for more than 300 years in Japan. In order to increase the available genomic resources for this species, 5651 expressed sequence tags (ESTs) were generated from seedling and winter bud cDNA libraries. After clustering and assembling ESTs, 2960 unigene elements that contain an homologous sequence to an S locus-linked gene of P. vulgaris were identified. In total, 127 simple sequence repeats (SSRs) were found. The most frequent di- and tri-SSR motifs were GA (78.6%) and ATT (12.9%), respectively. Twenty SSR and 40 single nucleotide polymorphism (SNP) markers were developed. These markers were evaluated for polymorphisms using 24 individuals (Y) from a population in Yatsugatake and 14 individuals (PS) from across the distributional range of P. sieboldii in Japan. The average level of expected heterozygosity within Y and PS was 0.39 and 0.48, respectively for EST-SSR markers and 0.26 and 0.29, respectively for SNP markers. The level of polymorphism for EST-SSR markers was lower than that for genomic SSR markers developed in a previous study. We also surveyed the genetic diversity of 56 cultivars, which had lower allelic richness than the Y and PS populations.
Stigma exsertion is an important trait that contributes to the improvement of seed production in hybrid rice. We demonstrate that GS3, one of the genes regulating seed length, also regulates stigma length and participates in stigma exsertion in rice. GS3 mRNA is expressed in the basal part of the young stigma, and a nonsense mutation in the second exon of GS3 causes an increase in cell number, resulting in elongation of the stigma. Manipulation of GS3 should contribute to the improvement of hybrid seed-production efficiency.
Characterization of resistance genes is essential for the development of a new variety resistant to blast (Magnaporthe grisea) in rice (Oryza sativa L.). In this study, we found that an indica variety, Kasalath, harbored a resistance gene that showed a broad spectrum of resistance reactions against standard differential blast isolates from the Philippines and Japan. Quantitative trait locus (QTL) analysis was conducted using backcross inbred lines derived from crosses between Kasalath and the japonica cultivar, Koshihikari, to detect the QTL for blast resistance. QTLs were detected on chromosomes 6 and 8. Further, QTL analysis of chromosome segment substitution lines of Kasalath in the Koshihikari genetic background revealed that the Kasalath allele at the QTL on chromosome 6 strongly contributed to blast resistance. These results suggested that the gene locus might be identical to Pi13(t) that had already been reported. By marker-assisted breeding, a near-isogenic line, Koshihikari Toyama BL7, with a Kasalath chromosome segment containing Pi13(t) introduced into Koshihikari genetic background, was developed. The reaction of Koshihikari Toyama BL7 to the differential blast isolates indicated that Pi13(t) was a broad-spectrum and moderate resistance gene. Since Pi13(t) showed single-gene segregation and was characterized, the gene was re-designated as Pi13.
The objectives of this study were to estimate the progress in wheat genetic yield potential, associated with changes in some agronomic traits, under different N rates. Twenty-four cultivars of winter wheat (T. aestivum L.) representing most of the cultivars released in Serbia from 1955 to 2006 were analyzed. The cultivars were grown for four years (2005–2008) in field trails with two levels of agronomic inputs (low nitrogen-N45 and high nitrogen-N110). Data were collected on 1000-kernel weight, kernels per spike, kernels per square meter, spikes per square meter, plant height, harvest index, heading time and grain yield. Mean difference between the two fertilization levels was 0.44 t ha−1. The average rate of increase in yield potential per year of release, estimated from the slope, was 41 kg ha−1 year−1 and it was significantly different from zero (P ≤ 0.01). It was 35 kg ha−1 year−1 or 0.55% at the low level of N input, and 46 kg ha−1 year−1 or 0.68% at the high level of N input. This suggests that modern cultivars are better adapted to high N input. Our results suggested that individual contribution of the most of analyzed traits may vary depending on the genotype as well as environmental conditions.
Grain size is one important trait in the agronomics of rice production. Although several quantitative trait loci (QTLs) controlling the length, width, and thickness of rice grains have been genetically identified, and some have been cloned, the molecular mechanisms of grain size regulation are still unclear. To identify the genetic factors affecting rice grain length, we performed QTL analysis using an F2 population and F3 lines derived from a cross between two Oryza sativa L. varieties: the long-grain japonica cultivar ‘Cytoto’ and the indica variety ‘Kasalath’. Three QTLs for grain length were detected, one each on chromosomes 3, 4 and 7. The presence of the Cytoto-type allele at any of the three loci was associated with increased grain length. Analysis of the QTL detected on chromosome 4, designated qGL4b, using F3 progeny confirmed an allelic difference between ‘Cytoto’ and ‘Kasalath’ at qGL4b. The Cytoto allele of qGL4b appears to increase the length and weight of the rice grain.
Semidwarf barley cultivars have been created in the past decades featuring shortened straw length. The semidwarfness trait is desirable because plants with reduced height are more resistant to lodging and, as a consequence, have an improved harvest index. Accordingly, both breeding and molecular mapping experiments were undertaken to enhance and evaluate the performance of semidwarf barley lines. To study the morpho-anatomical effects of the denso locus twenty barley lines developed by single seed descent technique were analysed. We measured several macro and microscopic traits of aboveground organs. We detected reduction in leaf size, which at tillering stage was also reflected by smaller sizes of some, but not all, categories of epidermal cells. Lower cell division frequencies were deduced for cell files with unchanged cell lengths. Denso leaf blades were thinner and had smaller vascular bundles and narrower tracheal elements compared to the wild type. On the other hand, a lack of effect was noted e.g. for sizes of stomata and size of spike. Denso gene thus exerted a multilevel dwarfing effect on cells, tissues and organs although not all organs and cells were affected to the same extent, and cell size or division frequency were modified depending on cell type.
We investigated the relationships between allelic variations on three Glu- loci, Glu-D1, Glu-A3 and Glu-B3, and processing qualities (dough strength and bread-making qualities) by using doubled haploid (DH) lines. The genotypic group of Glu-D1d had a longer mixing peak time (PT), a parameter of strong dough, than that of Glu-D1a. The group carrying Glu-B3g had a longer PT than that of the group carrying Glu-B3b when it was accompanied by Glu-D1d, and the group carrying Glu-A3d had a longer PT than that of the group carrying Glu-A3f when it was accompanied by Glu-D1d and Glu-B3g. Regarding the extent of the effects on dough strength, each of the two alleles on each of the three Glu- loci could be ranked as d > a on Glu-D1, d > f on Glu-A3 and g > b on Glu-B3. The wheat with compositions of d-f-b (allele on Glu-D1, Glu-A3 and Glu-B3, respectively) had the highest specific loaf volume (SLV), and d-d-g had lower SLV than those of other three combinations carrying Glu-D1d, although the dough strengths (PTs) of the d-f-b group was secondarily high and that of the d-d-g group was very high. It is considered that the d-d-g combination group has excessively strong dough and that the poor contribution of d-d-g combination to loaf volumes may be due to the extra-strong dough properties.
The tomatillo, Physalis ixocarpa Brot. (2n = 2x = 24), is an important crop in Mexico, and it is becoming appreciated in other countries. Polyploidy induction is expected to increase its breeding potential. The objective of this work was to develop and characterize tomatillo autotetraploids through colchicine-based induction. Young seedlings of the Rendidora cultivar were treated for 24 h with colchicine in concentrations ranging from 0.04% to 0.20%, and ploidy levels were tested by cytological and flow cytometry techniques. Autotetraploidy was induced with colchicine concentrations of 0.12% and 0.16%, with success rates of 67% and 65%, respectively. Presence of univalents, bivalents and multivalents was observed in prophase I and metaphase I. The basic genome size was not altered in the third generation progeny from treated plants. Autotetraploid plants were fertile and productive, but their pollen development was lower than their diploid counterpart. The polyploid plants showed higher values for life cycle length, plant height, fruit weight and equatorial diameter, fruits per plant, and soluble solid concentration. This is the first report of an autopolyploid cultivated tomatillo. Its genome duplication is readily induced with production of fertile plants, and may be valuable to introduce genetic plasticity in this crop.
Heading date (flowering time) in rice is a major factor in regional and seasonal adaptation. The shaping of adaptability to local areas has advantages for rice growth. In this study, we identified a quantitative trait locus (QTL) controlling heading date with a small effect in advanced backcrossed progenies. A near isogenic line (NIL) of rice variety Hoshinoyume for a major QTL controlling low-temperature germinability on chromosome 3, qLTG3-1, from Italica Livorno was developed. This NIL showed not only vigorous low-temperature germinability but also early heading with short culms compared with Hoshinoyume. QTL analysis revealed that a QTL controlling heading date, qDTH3, is located in the same chromosomal region as qLTG3-1. The late heading parent Italica Livorno-derived allele at qDTH3 showed early heading. Substitution mapping using a series of introgression lines carrying chromosomal segments from Italica Livorno revealed that qDTH3 involves multiple sub-QTLs, which have different genetic effects on the control of heading date. Recombination within the target region of qDTH3 provides new opportunities for altering heading date in local populations to shape adaptability.
A compatible individual-identification system with the multiplex SNuPE assay system, which was constructed of eighteen highly polymorphic and codominant single nucleotide polymorphisms (SNPs), was developed in the Japanese black pine (Pinus thunbergii Parl.). The eighteen SNPs were transformed into dominant markers by employing an allele-specific PCR (ASP) assay. Three multiplex PCR sets, each containing six ASP markers, were designed to increase cost saving and assay simplicity. Analyses of statistical parameters of 18 ASP markers revealed that gene diversity (H) and polymorphic information contents (PIC) were 0.331 to 0.500 (average of 0.425), and 0.375 to 0.500 (average of 0.473), respectively. The cumulative confusion probability (Ccumulative) of the system was extremely low (3.14 × 10−6), roughly one chance in 318,000 genotypes. The cumulative discrimination power (Dcumulative) was exceedingly high (0.999997), which means that the identification system is significantly powerful to discriminate the unrelated individuals.
A new, two-rowed, waxy, hull-less barley cultivar, Kirari-mochi, was bred by the pedigree breeding method, and derived from a three-way cross (Shikoku-hadaka 103/Daikei HL107 (ant28.494)) F1/Shikoku-hadaka 97 (wax). Kirari-mochi is both proanthocyanidin-free (ant28.494) and amylose-free (wax), and boiled pearled barley of Kirari-mochi showed lower levels of discoloration after incubation at high temperatures than Ichibanboshi (a standard cultivar of hull-less barley). The polyphenol content of pearled Kirari-mochi is roughly half that of Ichibanboshi and the β-glucan content of Kirari-mochi pearled barley is about 1.5-times higher than that of Ichibanboshi. The broken kernel ratio of Kirari-mochi is lower than that of Ichibanboshi. Although the grain yield of Kirari-mochi is approximately 85% of that of Ichibanboshi, its tolerance to pre-harvest sprouting is lower than that of Ichibanboshi. Kirari-mochi is resistant to both barley yellow mosaic virus and powdery mildew, and is moderately resistant to scab. Kirari-mochi is well adapted to cultivation in the plains of central and western Japan, and it was released in 2010. Kirari-mochi is suitable for pearling and boiling, and has good eating quality.
One thousand five hundred rapeseed accessions were collected from gene banks in several countries and surveyed for their seed traits such as oil content, protein content, fatty acid composition and seed weight. Seed chemicals were analyzed by near-infrared reflectance spectroscopy (NIRS). An extensive genetic variation existed among accessions for all seed traits examined. The oil content ranged from 24.7 to 56.9%, and the protein content ranged from 6.7 to 36.6%. A hundred seed weight ranged from 0.13 to 0.70 g. The fatty acid compositions of germplasms also varied from 2.6 to 9.2% of C16:0 (palmitic acid), 0.3 to 70.2% of C18:1 (oleic), 10.3 to 28.9% of C18:2 (linoleic), 4.8 to 15.3% of C18:3 (linolenic), 0 to 10.5% of C20:1(eicosenoic) and 0 to 59.6% of C22:1 (erucic). The oil content had strong negative correlation with protein content (r = −0.848). However, it did not have any close correlations with other traits. When the genetic stability of seed traits was examined by comparison between original seeds and self-pollinated seeds (S1 seeds), higher positive and significant correlation coefficients between original seeds and S1 seeds were found in all seed traits.