18 research outputs found
Path Analysis of Tiller Density of Winter Wheat Demonstrates the Importance of Practices that Manipulate Clod Size Based on Soil Moisture at Seeding in the Rice–Wheat Cropping System
The moisture of paddy soil after rice cropping is a major impediment to the establishment, tillering and yield of winter wheat in the rice−wheat (R−W) cropping system. We examined the seedling establishment ratio, based on soilmoisture at seeding by path analysis of nine soil/plant traits in the farmer's fields in Western Japan where the R−W cropping system was being used, to establish a strategy for improving tiller density by optimizing the seedling establishment ratio. The clod size of surface soil, which showed a significant positive correlation with soil moisture at seeding, had a significant negative direct effect on the seedling establishment ratio. The reduction in seedling establishment ratio, together with fewer tillers per plant, resulted in a significant decrease in tiller density. The sum total of contribution of soil moisture contents to tiller density via clod size was smaller than that of seeding rate, and similar to that of the amount of nitrogen (N) basal dressing. This indicates that manipulating clod size based on soil moisture at seedingprovides an opportunity for maintaining tiller density, as well as changing the amount of N basal dressing with the soil moisture conditions after rice cropping
Path Analysis of Tiller Density of Winter Wheat Demonstrates the Importance of Practices that Manipulate Clod Size Based on Soil Moisture at Seeding in the Rice–Wheat Cropping System
Multifamily QTL analysis and comprehensive design of genotypes for high-quality soft wheat.
Milling properties and flour color are essential selection criteria in soft wheat breeding. However, high phenotypic screening costs restrict selection to relatively few breeding lines in late generations. To achieve marker-based selection of these traits in early generations, we performed genetic dissection of quality traits using three doubled haploid populations that shared the high-quality soft wheat variety Kitahonami as the paternal parent. An amplicon sequencing approach allowed effective construction of well-saturated linkage maps of the populations. Marker-based heritability estimates revealed that target quality traits had relatively high values, indicating the possibility of selection in early generations. Taking advantage of Chinese Spring reference sequences, joint linkage maps of the three populations were generated. Based on the maps, multifamily quantitative trait locus (QTL) analysis revealed a total of 86 QTLs for ten traits investigated. In terms of target quality traits, 12 QTLs were detected for flour yield, and 12 were detected for flour redness (a* value). Among these QTLs, six for flour yield and nine for flour a* were segregating in more than two populations. Some relationships among traits were explained by QTL collocations on chromosomes, especially group 7 chromosomes. Ten different ideotypes with various combinations of favorable alleles for the flour yield and flour a* QTLs were generated. Phenotypes of derivatives from these ideotypes were predicted to design ideal genotypes for high-quality wheat. Simulations revealed the possibility of breeding varieties with better quality than Kitahonami
The genome sequence of sweet cherry (Prunus avium) for use in genomics-assisted breeding
Additional Nitrogen Fertilization at Heading Time of Rice Down-Regulates Cellulose Synthesis in Seed Endosperm
<div><p>The balance between carbon and nitrogen is a key determinant of seed storage components, and thus, is of great importance to rice and other seed-based food crops. To clarify the influence of the rhizosphere carbon/nitrogen balance during the maturation stage of several seed components, transcriptome analysis was performed on the seeds from rice plants that were provided additional nitrogen fertilization at heading time. As a result, it was assessed that genes associated with molecular processes such as photosynthesis, trehalose metabolism, carbon fixation, amino acid metabolism, and cell wall metabolism were differentially expressed. Moreover, cellulose and sucrose synthases, which are involved in cellulose synthesis, were down-regulated. Therefore, we compared cellulose content of mature seeds that were treated with additional nitrogen fertilization with those from control plants using calcofluor staining. In these experiments, cellulose content in endosperm from plants receiving additional nitrogen fertilization was less than that in control endosperm. Other starch synthesis-related genes such as starch synthase 1, starch phosphorylase 2, and branching enzyme 3 were also down-regulated, whereas some α-amylase and β-amylase genes were up-regulated. On the other hand, mRNA expression of amino acid biosynthesis-related molecules was up-regulated. Moreover, additional nitrogen fertilization caused accumulation of storage proteins and up-regulated Cys-poor prolamin mRNA expression. These data suggest that additional nitrogen fertilization at heading time changes the expression of some storage substance-related genes and reduces cellulose levels in endosperm.</p></div
Rice cultivation schedule.
<p>Samples were grown in a growth chamber at 28°C/22°C over a 12-h light/12-h dark cycle. Fertilizer was supplied at planting and 37 days after germination. In addition, 400 mg ammonium chloride (NH<sub>4</sub>Cl) was supplied at heading time to the “+NH<sub>4</sub>Cl” group.</p
Changes in gene expression and rice seed compounds with additional fertilization.
<p>Notable change in mRNA expression and seed compounds are summarized. Molecules in the open oval are DEGs from DNA microarray experiments. Rectangles show the compound whose content was measured in this study. Red and blue arrows indicate up- and down-regulation by additional nitrogen fertilization, respectively. SUS3, sucrose synthase 3; CESA, cellulose synthase A catalytic subunit; SBE3, starch-branching enzyme 3; SS1, starch synthase 1; SP2, starch phosphorylase 2; αAmy, α-amylase; βAmy, β-amylase.</p
Cluster dendrogram.
<p>A cluster dendrogram was generated using rice seed gene expression data from six samples and the “pvclust” function. Each sample was prepared at 15-DAF seeds from 24 control or 24 N-fertilized plants and were pooled. Three sets of five seeds were picked from each seed pool. C, control samples; N, N-fertilized samples.</p