Increasing grain yield and protein are important wheat breeding goals. However, the simultaneous improvement of both traits is complicated by a strong negative correlation and genotype by environment interaction (G×E). A recurrent selection program (RSP) reported here was initiated to produce germplasm, which combined both high yield-potential and increased protein content for the northern wheat-growing region of Australia. Diallel crossing amongst 10 cultivars (6 high yield and 4 high quality cultivars), followed by random mating amongst the F1s were used to produce the founding segregating population. Two years of multi-environment trials were conducted in the GRDC Northern Grain Region (NR) for each of the foundation (RSA0) and first (RSA1) cycles of recurrent selection. Data from the two cycles were analysed to evaluate the genetic gain achieved over the two cycles of selection, based on five potential selection strategies. Selection based on yield or protein or yield-adjusted protein only increased selected trait but reduced the other traits. However, application of selection based on yield and protein or yield and yield-adjusted protein simultaneously increased both yield (4.7%, 6.0% for RSA0 and 4.0%, 4.2% for RSA1 respectively) and protein (2.1%, 1.3% for RSA0 and 1.7%, 1.6% for RSA1 respectively).
Control of the amylose content is a major strategy for breeding rice with improved eating quality. To identify the low-amylose gene of the low-amylose rice cultivar Oborozuki, quantitative trait loci (QTL) and sequence analyses were conducted on 90 progeny obtained by crossing the two japonica cultivars Hokka287 (a donor parent of Oborozuki) and Hokkai-PL9. One QTL for low amylose content was detected on the WX1 locus on the short arm of chromosome 6. This gene was designated Wx1-1 for the Hokkai287 allele, and is a novel allelic gene for the WX1 locus with a 37-bp deletion in intron 10. Homozygote genotype for Wx1-1 decreased the amylose content by 7.8%. Primer sets Wx-U1L3 designed to amplify the genome region containing the deletion clearly differentiated cultivars containing Wx1-1 from others. This DNA marker is useful for breeding cultivars with low amylose contents. Another QTL, qAC9.3, was detected on the short arm of chromosome 9. Hokkai-PL9-homozygote allele for qAC9.3 decreased the amylose content by 2.6%. QTL analyses showed that Wx1-1 and the Hokkai-PL9 allele of qAC9.3 have an additive effect in decreasing the amylose content. The two genes are useful tools in marker-assisted selection when breeding rice with a controlled amylose content for improved eating quality.
Genetic variability and its spatial structure within and among Japanese populations of wild radish Raphanus sativus L. var. hortensis Backer f. raphanistroides Makino were surveyed at regional (<250 km) and local (<3.5 km) scales using eight microsatellite markers. A regional-scale survey was performed on seven populations from sandy coasts of the Sea of Japan. For local-scale survey, 10 subpopulations were sampled along the sandy seashore of Kumihama coast. The level of genetic variability was similar between regional (HT = 0.577) and local (HT = 0.604) samples. Local populations and subpopulations showed heterozygote deficiency as expressed by average inbreeding coefficient values of 0.206 and 0.179, respectively. The level of genetic differentiation among populations was low, with fixation index values of 0.048 and 0.034 for regional and local scales, respectively. Nonetheless, analysis of molecular variance showed significant genetic differentiation among populations/subpopulations. Spatial genetic analysis indicated a positive correlation between pairwise values of spatial distance and genetic differentiation both at regional and local levels. These results suggest that the wild radish populations surveyed are genetically structured and each population retains a unique genetic composition. Genetic heterogeneity among local populations provides the opportunity to obtain genetic resources with various useful traits by extensive exploration of different populations.
For F1 seed production in Brassicaceae crops, cross-pollination between the two parental lines is vital and is dependent on the visitation behavior of insect pollinators. In a radish F1 seed production field using cytoplasmic male sterility system, visitation behaviors of different pollinator species and seed productivity of the recipient line were investigated in three stages during the flowering. As a result, honey bees (Apis mellifera and A. cerana) selectively visited either of two lines, while syrphid flies (various flies belonging to Syrphidae) tended to visit both lines. Despite the few observations of pollinator movements between the two lines, all flowers had received cross-pollen grains a few days after flowering. But in the late stage of flowering, increased cross-pollination by syrphid flies appeared to lead to an increase in the amount of cross-pollen grains deposited on the stigmas. The percentage of pod set and the number of seeds per pod varied among the three stages of the flowering. These variations might be caused by shifts in the amount of cross-pollen grains deposited on the stigmas due to the pollinators’ selective visitation behaviors. The selective visitation behavior of insect pollinators could potentially result in unstable F1 seed production through the insufficient cross-pollination.
Because of the huge morphological variations exhibited there, the Abyssinian Highlands (Ethiopia) are thought of as the secondary center of diversity of domesticated emmer wheat (Triticum turgidum L.). The genetic diversity in 88 domesticated emmer wheat accessions from Ethiopia and other regions was analyzed using DNA sequences of parts of four genes, Acc1-A, Pgk1-B, Waxy-A and Waxy-B, which are single-copy genes in nuclear DNA. The multilocus genotypes determined by analysis using Structure enabled the 88 accessions to be divided into four clusters. Each cluster included both hulled and free-threshing subspecies, and there was no clustering corresponding to specific subspecies. Both hulled and free-threshing emmer landraces in Ethiopia had several characteristic alleles, and the gene flow between them was shown to be limited. The genetic composition of Ethiopian landraces differed from that of emmer in other regions of the world. However, their nucleotide diversity was not as high as that of other emmer populations. The large morphological diversity in Ethiopian emmer landraces must have evolved from a limited genetic background.
Grain texture is one of the most important characteristics that affect the end-use quality of wheat (Triticum aestivum L.). Mutations in the puroindoline-a and puroindoline-b genes are associated with hard grain texture. The expression patterns of the PINA and PINB proteins differ among Pin alleles. We studied the effect of Pin alleles on grain hardness, and milling flour properties using near isogenic lines grown at two different locations. The genotype was found to significantly affect quality parameters related to grain hardness. Grain hardness, flour particle size, damaged starch content were significantly low in Pinb-D1b as compared to Pinb-D1c, Pinb-D1p, Pina-D1b, and Pina-D1k. Grain hardness of Pina-D1k, lacking both PINA and PINB, were the highest, followed by Pina-D1b lacking PINA. Pina-D1k and Pina-D1b showed high damaged starch contents and CO2 production. Damaged starch is associated with water absorption of flour and CO2 production during dough fermentation, an important characteristic in bread-making. The alleles might be useful for improving bread-making quality. These results indicate that the grain texture of hard wheat is affected by the amount of PINs each allele.
Puroindoline genotypes, grain characteristics, physico-chemical properties of flour and end-use qualities of Korean wheat cultivars were evaluated to determine the influence of puroindolines genotypes and to provide on those characteristics. Nine Korean wheat cultivars carried Pina-D1a/Pinb-D1a, fourteen had Pina-D1a/Pinb-D1b, and three had Pina-D1b/Pinb-D1a. Pina-D1b/Pinb-D1a and Pina-D1a/Pinb-D1b genotypes showed significantly higher 1000-kernel weight and hardness index in grain characteristics, higher flour yield, average particle size, ash and protein content, SDS-sedimentation volume, water absorption and mixing time of mixograph, thickness of noodle dough sheet and lower values in lightness of flour and cookie diameter than Pina-D1a/Pinb-D1a genotype. The Pina-D1b/Pinb-D1a genotype showed significantly higher damaged starch content and water retention capacity than other genotypes. Hardness index of grain was positively correlated with flour yield and average particle size of flour. Those parameters were positively correlated with damaged starch, water retention capacity, SDS-sedimentation volume and water absorption of mixograph, and negatively correlated with lightness of wheat flour. In end-use qualities, thickness and lightness of noodle dough sheet and cookie diameter were correlated with hardness index, milling performances and physical properties. However, bread volume and texture of cooked noodles were not influenced by milling performances and physical properties.
Soybean (Glycine max (L) Merr.) isoflavones have attracted considerable attention for their diverse effects on human health. To determine the genetic factors that contribute to the high isoflavone contents of the soybean varieties ‘Peking’ and ‘Tamahomare’, we conducted QTL analyses for the total content of daidzein derivatives (DAC), genistein derivatives (GEC) and glycitein derivatives (GLC), and for the total content of isoflavones (TIC) using recombinant inbred lines (RILs) derived from the cross between ‘Peking’ and ‘Tamahomare’. Ninety six RILs were planted in Kyoto, Osaka and Nagano in 2003 and in Osaka and Nagano in 2004. Transgressive segregation for TIC was detected in all the environments tested. Composite interval mapping for TIC revealed four QTLs: qIso1, qIso2, qIso3 and qIso4, located on LG-A1 (Chr.5), LG-A2 (Chr.8), LG-C1 (Chr.4) and LG-D2 (Chr.17), respectively. The high-isoflavone alleles were derived from Peking at qIso1 and qIso4 and from Tamahomare at qIso2 and qIso3. Several other groups have already reported the former two QTLs, but qIso2 and qIso3 are new discoveries. Our results indicate that the large variation in TIC measurements observed in the RILs could have resulted from the combined effects of alleles at the four QTLs derived from distantly related varieties.
Genetic diversity among 59 melon landraces from Vietnam was studied by analyzing morphological traits and molecular markers. The morphological characters of the melon landrace fruits were highly diversified. Among the five types of cultivated melon, “Dua le” and “Dua vang” were classified as Conomon var. makuwa, whereas “Dua gang” was classified as Conomon var. conomon, and “Dua bo” was classified as Momordica. However, “Dua thom” could not be classified into a proper group or variety. The gene diversity based on random amplified polymorphic DNA (RAPD) and single sequence repeat analyses was small and equivalent to that of Chinese Conomon. A cluster analysis revealed that “Dua bo”, “Dua le”, “Dua vang”, and “Dua gang” were grouped in cluster II. Clusters III and IV consisted mainly of Conomon accessions from China and Japan. “Dua thom” was classified into cluster V with landraces from Yunnan Province, China. The comparison of a RAPD profile with 291 melon accessions from Africa and Asia clearly showed that “Dua thom” and Yunnanese landraces were closely related with the small-seed type melons from Myanmar, Bangladesh, and northeastern India. The other four types were related closely with Conomon and Agrestis accessions from China, Korea, and Japan, indicating their involvement in the differentiation and establishment of the Conomon group in East Asia.
The “Crossing-within-Spike-Progeny (CSP) method” is a method to efficiently screen for mutants in allogamous (cross-fertilizing) plants. This paper presents a theoretical analysis of how to minimize the total number of plants in the screening generation (T) and the total cost (Tc) required to detect one or more mutants with a given probability when using the CSP method. Tc depends on the number of plants per line in the screening generation (n), the number of plants per hill plot in the M2 generation (h), the ratio of the cost needed in non-screening generations to that in the screening generation (W), and the mutation rate per cell (p1). T was lowest when n = 1 (T = 47.93 × p1−1), irrespectively of h. On the other hand, the value of n which gave minimum Tc (designated n*) was not constant, but varied with h. n* was 6 when h = 2, increased as h increased, and was 15 when h = 48, when W = 10. Unlike in the case of autogamous species, the presence of chimeras in the M1 inflorescences greatly increased both T and Tc. A method for estimating the mutation rate per cell is also presented.
Transgenic Italian ryegrass plants expressing the betaine aldehyde dehydrogenase gene of zoysiagrass (ZBD1) were produced via particle bombardment of embryogenic calluses. Although the growth of both non-transgenic and transgenic plants expressing ZBD1 was inhibited under salt stress, isolated tillers of the transgenic plants showed better re-rooting ability in vitro in the presence of 300 mM NaCl. Chlorophyll fluorescence values of the transgenic plants declined under salt stress, but were significantly higher than those of non-transgenic plants under salt stress, indicating the improved salt stress tolerance of transgenic plants.
Bread wheat (Triticum aestivum) is a hexaploid species with A, B and D genomes. Therefore, most bread wheat genes are present in the genome as triplicated homoeologous genes (homoeologs) derived from the ancestral A, B, and D genome diploid species. Maturing-time, which is associated with flowering-time and the grain-filling period, is one of the most important agronomic traits for wheat breeding. Here, the effects of homoeologs derived from D genome diploid species on maturing-time in bread wheat were examined in synthetic hexaploid wheats obtained by crossing tetraploid durum wheat T. turgidum ssp. durum cv. Langdon and three accessions of the D genome diploid species (Aegilops tauschii). After vernalization, the synthetic hexaploid wheat derived from an early-flowering D genome donor showed an early-flowering phenotype among the synthetic hexaploids, whereas the synthetic wheat derived from a late-flowering D genome donor was late-flowering among the synthetic hexaploids. This suggests that the early-flowering phenotype in hexaploid wheat is affected by the homoeolog for early-flowering in the D genome donor. In contrast, maturing-time and grain-filling period in the synthetic hexaploids did not correspond with those of the D genome donors, suggesting that these traits are controlled by the interaction between homoeologs on the A, B and D genomes in hexaploid wheat.