Search

Effective tiller number (ETN) directly affects panicle number and is closely related to wheat grain yield. Mining quantitative trait loci (QTLs) associated with wheat tiller number and analyzing the correlation between tiller number and other important agronomic traits can provide the theoretical basis for molecular breeding. In this study, we first proposed and established a novel genetic analysis framework of "multiple environmental assessments-depth analysis of individual traits-comprehensive evaluation of various traits-friendly marker development-verification in different backgrounds". Using this approach, low-tillering QTLs were identified and validated base on an F6 recombinant inbred line population (MC population) derived from the low-tillering plant msf and Chuannong 16 (CN16), phenotypic data of effective tillers from multiple environments, and a 16K chip-based constructed genetic linkage map. QTL mapping results showed that there were four QTLs controlling tillering on chromosomes 1A, 5A, and 6D, respectively. Qltn.sau-MC-1A was a stable and major low-tillering QTL explaining 13.39%--60.40% of the phenotypic variation rate, and its positive allele was from msf. Phenotypic analysis showed that ETN of the lines carrying the positive allele of Qltn.sau-MC-1A was significantly less than those with the negative alleles. Correlation analysis showed that ETN had a significantly positive correlation with plant height (PH), and a significantly negative correlation with thousand kernel weight (TKW), kernel number per spike (KNPS), kernel weight per spike (KWPS), and flag leaf width (FLW), but no significantly correlation with flag leaf length (FLL) and anthesis date (AD). Genetic analysis showed that positive allele of Qltn.sau-MC-1A had a significant effect on increasing KNPS, KWPS, and TKW, but delaying AD. Validation results in different backgrounds suggested that the ETN of lines carrying positive alleles from Qltn.sau-MC-1A could be significantly decreased. Collectively, we established a new genetic mapping approach and further used it to identify and validate a major QTL controlling low-tiller number, Qltn.sau-MC-1A, which laid a foundation for further fine mapping and understanding the mechanism of tiller formation. [ABSTRACT FROM AUTHOR]

Objective To evaluate the influence of different heat treatments on the corrosion behavior of a new Pd⁃ Ag⁃In⁃Ga alloy. Methods The corrosion of a new Pd⁃Ag⁃In⁃Ga alloy was tested according to ISO 10271：2001/cor.1: 2005(E). Taken as comparison, a commercial high⁃palladium alloy (Spartan® Plus) was also employed in the study. For electrochemical corrosion test, the open ⁃circuit potential (Eocp) and potentiodynamic polarization curve were recorded and then the electrochemical parameters, namely corrosion potential (Ecorr) and corrosion current density (Icorr) calcu⁃ lated. The surfaces of the specimens that before and after corrosion test were observed by scanning electron microscopy (SEM). Results Both of the high ⁃ palladium alloys had lower corrosion tendency and higher corrosion resistance by heat treatment in the ISO 10271 electrochemical corrosion test. For both alloys, heat treatment at 500 ℃ was found to be effective in improving the corrosion resistance as the best datas of electrochemical parameters (Eocp, Ecorr, Icorr) were detected among the four temperature groups. However, no evidence showed that there was significant difference in corrosion resistance between the two alloys. Comparison of surface morphology of the specimens before and after electro⁃ chemical experiments by SEM demonstrated that all groups of the two alloys were visible of pitting corrosion and crevice corrosion phenomenon that gradually became less with increasing heat treatment temperature. Horizontal comparing among the groups of the two alloys, no apparent differences in the distribution of pitting and crevice corrosion was found. Conclusion The variation in compositions of high⁃palladium alloys did not cause significant difference in corro⁃ sion behavior due to the identical palladium matrix. The similarity in corrosion behavior among the two high⁃palladium alloys might be attributed to the predominant palladium content.