scholarly journals Differentially directional selection on grain size genes identified by RapMap during rice domestication

2020 ◽  
Author(s):  
Yibo Li ◽  
Juncheng Zhang ◽  
Dejian Zhang ◽  
Yawei Fan ◽  
Cuicui Li ◽  
...  
Keyword(s):  
Grain Size ◽  
Population Level ◽  
Isogenic Line ◽  
Molecular Architecture ◽  
Mini Core Collection ◽  
Trait Locus ◽  
Grain Size And Shape ◽  
Selection Intensities ◽  
Genetic Contributions ◽  
Rice Domestication

Abstract The ability to identify quantitative trait locus (QTL) genes controlling natural variation of important traits would facilitate the construction of a bridge between gene function analyses and domestication investigations. Grain size in rice is an important yield, quality and domestication trait. The molecular architecture and domestication signatures of grain size at population level remain unknown. Here we first introduce RapMap, a method for rapid and high-throughput QTL mapping employing a series of F2 gradient populations (F2GPs) constructed by trait-adjacent accessions from diverse germplasms. A co-segregation standard is set for simultaneously integrating the three-in-one framework in RapMap: detecting a real QTL, confirming its effect and obtaining its near-isogenic line-like line (NIL-LL), which greatly enhances the efficiency and robustness of QTL identification. Using 15 gradient populations, eight genes including two novel genes (GL1 and GW5.1) with different effects for grain size in rice were simultaneously discovered by RapMap in three years, which make more than two thirds of genetic contributions to grain size and shape in a mini-core collection worldwide. In-depth analyses of the eight genes employing a large and geographically diverse population, including 446 wild, 2462 landrace and 784 cultivar accessions, revealed that directional artificial selection of slender- and long- grains and their alleles played an important role during indica rice domestication. The genetic effects of the eight grain-size genes positively correlate with the differential selection intensities and the nucleotide variation intensities. Major grain-size genes fixed before the completion of rice domestication have been heavily selected for human requirements and cultivation practices. Generalizable application of the method and mimicking of the domestication nature will accelerate breeding modern cultivars.

scholarly journals The identification of grain size genes by RapMap reveals directional selection during rice domestication

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Juncheng Zhang ◽  
Dejian Zhang ◽  
Yawei Fan ◽  
Cuicui Li ◽  
Pengkun Xu ◽  
...  
Keyword(s):  
Grain Size ◽  
Germplasm Collection ◽  
Directional Selection ◽  
Rice Grain ◽  
Isogenic Line ◽  
Shape Variation ◽  
Genomic Breeding ◽  
Simultaneous Integration ◽  
Trait Locus ◽  
Rice Domestication

AbstractCloning quantitative trait locus (QTL) is time consuming and laborious, which hinders the understanding of natural variation and genetic diversity. Here, we introduce RapMap, a method for rapid multi-QTL mapping by employing F2 gradient populations (F2GPs) constructed by minor-phenotypic-difference accessions. The co-segregation standard of the single-locus genetic models ensures simultaneous integration of a three-in-one framework in RapMap i.e. detecting a real QTL, confirming its effect, and obtaining its near-isogenic line-like line (NIL-LL). We demonstrate the feasibility of RapMap by cloning eight rice grain-size genes using 15 F2GPs in three years. These genes explain a total of 75% of grain shape variation. Allele frequency analysis of these genes using a large germplasm collection reveals directional selection of the slender and long grains in indica rice domestication. In addition, major grain-size genes have been strongly selected during rice domestication. We think application of RapMap in crops will accelerate gene discovery and genomic breeding.

scholarly journals Dissection of Two QTL for Grain Size Linked on the Long Arm of Chromosome 5 in Rice

2021 ◽  
Author(s):  
xiaojun Niu ◽  
Zhenhua Zhang ◽  
Aye Nyein Chan ◽  
Yeyang Fan ◽  
Shaoqing Tang ◽  
...  
Keyword(s):  
Grain Size ◽  
Complex Traits ◽  
Grain Weight ◽  
Isogenic Line ◽  
Nucleotide Polymorphisms ◽  
Appearance Quality ◽  
Trait Locus ◽  
Significant Expression ◽  
Agronomical Traits ◽  
Previous Identification

Abstract Background: Most agronomical traits of crops are complex traits controlled by several major quantitative trait locus (QTL) and many minor QTL. Grain size determines grain weight and influences rice appearance quality. Identification of minor QTL is important for understanding the genetic and molecular network regulating grain size in rice. Following previous identification of QTL for grain weight and size using populations derived from the Teqing/IRBB52 indica rice cross, one QTL, qTGW5/qGL5 having significant effects on grain weight and length, was targeted for validation, dissection and fine-mapping.Result: Firstly, the effect of qTGW5/qGL5 was validated using two near isogenic line (NIL) F2 populations. Then, qTGW5/qGL5 was dissected into two closely linked QTL for grain size using four sets of NILs with sequential segregating regions. One of them, qTGW5 with the IRBB52 alleles increased grain weight, length and width with the same allelic direction, was located within an 1896.4-kb region flanked by RM18865 and Fi25273. The other one, qGL5 controlling grain length, was further delimited into a 68.8-kb region using seven NIL-F2 populations. Six annotated genes were found in the qGL5 region, of which five showed nucleotide polymorphisms between the two parental lines. In three of the six annotated genes, significant expression differences were detected between qGL5-NILs.Conclusions: Two closely-linked QTL having small effects for grain size in rice were separated using NIL-derived populations. One of them, qGL5 was fine-mapped into a 68.8-kb region containing six annotated genes. Our work lays a foundation for cloning minor QTL for grain size and offers potential targets for marker-assisted breeding in rice.

scholarly journals Verification and dissection of one quantitative trait locus for grain size and weight on chromosome 1 in rice

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Yi-chen Cheng ◽  
Guan Li ◽  
Man Yin ◽  
Tosin Victor Adegoke ◽  
Yi-feng Wang ◽  
...  
Keyword(s):  
Grain Size ◽  
Quantitative Trait ◽  
Genetic Background ◽  
Molecular Design ◽  
Chromosome 1 ◽  
Recurrent Parent ◽  
Isogenic Line ◽  
Growing Seasons ◽  
Ril Population ◽  
Trait Locus

AbstractGrain size and weight are the key traits determining rice quality and yield and are mainly controlled by quantitative trait loci (QTL). In this study, one minor QTL that was previously mapped in the marker interval of JD1009-JD1019 using the Huanghuazhan/Jizi1560 (HHZ/JZ1560) recombinant inbred line (RIL) population, qTGW1-2, was validated to regulate grain size and weight across four rice-growing seasons using twenty-one near isogenic line (NIL)-F2 populations. The twenty-one populations were in two types of genetic background that were derived from the same parents HHZ and JZ1560. Twelve F9, F10 or F11 NIL-F2 populations with the sequential residual heterozygous regions covering JD1009-RM6840 were developed from one residual heterozygote (RH) in the HHZ/JZ1560 RIL population, and the remaining nine BC3F3, BC3F4 or BC3F5 NIL-F2 populations with the sequential residual heterozygous regions covering JD1009-RM6840 were constructed through consecutive backcrosses to the recurrent parent HHZ followed with marker assistant selection in each generation. Based on the QTL analysis of these genetic populations, qTGW1-2 was successfully confirmed to control grain length, width and weight and further dissected into two QTLs, qTGW1-2a and qTGW1-2b, which were respectively narrowed down to the marker intervals of JD1139-JD1127 (~ 978.2-kb) and JD1121-JD1102 (~ 54.8-kb). Furthermore, the two types of NIL-F2 populations were proved to be able to decrease the genetic background noise and increase the detection power of minor QTL. These results provided an important basis for further map-based cloning and molecular design breeding with the two QTLs in rice.

scholarly journals Snow dielectric properties: from DC to microwave X-band

1994 ◽  
Vol 19 ◽  
pp. 92-96 ◽  
Author(s):  
TH. Achammer ◽  
A. Denoth
Keyword(s):  
Grain Size ◽  
Dielectric Properties ◽  
Water Content ◽  
Liquid Water ◽  
Liquid Water Content ◽  
Frequency Range ◽  
Snow Density ◽  
Cold Room ◽  
X Band ◽  
Grain Size And Shape

Broadband measurements of dielectric properties of natural snow samples near or at 0°C are reported. Measurement quantities are: dielectric permittivity, loss factor and complex propagation factor for electromagnetic waves. X-band measurements were made in a cold room in the laboratory; measurements at low and intermediate frequencies were carried out both in the field (Stubai Alps, 3300 m; Hafelekar near Innsbruck, 2100 m) and in the cold room. Results show that in the different frequency ranges the relative effect on snow dielectric properties of the parameters: density, grain-size and shape, liquid water content, shape and distribution of liquid inclusions and content of impurities, varies significantly. In the low-frequency range the influence of grain-size and shape and snow density dominates; in the medium-frequency range liquid water content and density are the dominant parameters. In the microwave X-band the influence of the amount, shape and distribution of liquid inclusions and snow density is more important than that of the remaining parameters.

Magnetic Properties of Sputtered Fe-O and Co-O Thin Films

1995 ◽  
Vol 403 ◽  
Author(s):  
D. V. Dimitrov ◽  
A. S. Murthy ◽  
G. C. Hadjipanayis ◽  
C. P. SWANN
Keyword(s):  
Grain Size ◽  
Low Temperatures ◽  
Room Temperature ◽  
Oxide Films ◽  
X Ray Diffraction ◽  
Dc Magnetron Sputtering ◽  
Large Shift ◽  
X Ray ◽  
Grain Size And Shape ◽  
Spherical Grains

AbstractFe-O and Co-O films were prepared by DC magnetron sputtering in a mixture of Ar and O2 gases. By varying the oxygen to argon ratio, oxide films with stoichiometry FeO, Fe3O4, α-Fe2O3, CoO and Co3O4 were produced. TEM studies showed that the Fe – oxide films were polycrystalline consisting of small almost spherical grains, about 10 nm in size. Co-O films had different microstructure with grain size and shape dependent on the amount of oxygen. X-ray diffraction studies showed that the grains in Fe-O films were randomly oriented in contrast to Co-O films in which a <111> texture was observed. Pure FeO and α-Fe2O3 films were found to be superparamagnetic at room temperature but strongly ferromagnetic at low temperatures in contrast to the antiferromagnetic nature of bulk samples. A very large shift in the hysteresis loop, about 3800 Oe, was observed in field cooled Co-CoO films indicating the presence of a large unidirectional exchange anisotropy.

The Effects of Microstructure on Properties

2004 ◽  
pp. 39-46
Keyword(s):  
Mechanical Properties ◽  
Grain Size ◽  
Detailed Examination ◽  
Intermetallic Phases ◽  
Primary Phase ◽  
Silicon Alloys ◽  
Aluminum Silicon Alloys ◽  
Aluminum Castings ◽  
Eutectic Modification ◽  
Grain Size And Shape

Abstract In castings, microstructural features are products of metal chemistry and solidification conditions. The microstructural features, excluding defects, that most strongly affect the mechanical properties or aluminum castings are size, form, and distribution of intermetallic phases; dendrite arm spacing; grain size and shape; and eutectic modification and primary phase refinement. This chapter discusses the effects of these microstructural features on properties and methods for controlling them. The chapter concludes with a detailed examination of the refinement of hypereutectic aluminum-silicon alloys.

MICROSTRUCTURAL CHANGES OF ALUMINIUM ALLOY A319 ON COOLING SLOPE PLATE

2016 ◽  
Vol 78 (6-9) ◽  
Author(s):  
Ahmad Muhammad Aziz ◽  
Mohd Zaidi Omar ◽  
Zainuddin Sajuri ◽  
Mohd Shukor Salleh
Keyword(s):  
Grain Size ◽  
Shape Factor ◽  
Casting Process ◽  
Impact Zone ◽  
Dendritic Microstructure ◽  
Size And Shape ◽  
Cooling Slope ◽  
Grain Size And Shape ◽  
Bottom Zone ◽  
The Impact

The cooling slope (CS) casting process is one of the simplest methods for producing a non-dendritic microstructure. To more clearly determine how this microstructure is formed, specifically in A319, requires an examination of how the dendritic microstructure evolves along the entirety of the CS plate. Yet until now, there are still unclear on the verification of microstructures changes on the CS plate. Based on experimental results, this paper offers an explanation for the mechanism involved in producing a nearly globular microstructure in A319. In addition, the mechanism is verified by using the planimetry method. Moreover a quantitative method is used to determine the grain size and shape factor to provide further support for the proposed mechanism. The solid fraction of α-Al at the impact zone is 70 % which is the highest compared to other zones. Grain size and shape factor shown a decreasing and increasing value respectively from the impact zone until the bottom zone.

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