SNP-based QTL mapping for panicle traits in the japonica super rice cultivar Liaoxing 1

Panicle traits directly associated with yield are a target of selection in rice breeding.Although abundant QTL for panicle traits have been identified,there is little information about the genetic basis of panicle traits in japonica super rice(JSR)cultivars.In this study,we identified QTL for panicle traits in three environments using a population of recombinant inbred lines(RILs)derived from the JSR cultivar Liaoxing 1.A total of 197 RILs were genotyped with 285 polymorphic SNP markers.Phenotypic data and best linear unbiased prediction(BLUP)value of primary branch number(BNP),secondary branch number(BNS),grain number on primary branch(GNP),grain number on secondary branch(GNS),grain number per panicle(GN),panicle length(PL)and grain density(GD)were used for QTL mapping.A total of 105 QTL for seven panicle traits were detected in single environments using their BLUP values.Individual QTL explained 0.51%–52.22%of the phenotypic variation.Of the 105,49 were also detected by joint multi-environment analyses.Five stable QTL:qGD9,qPL9,qGNP9,qGN6,and qBNS6.2 were identified in multiple environments.qGD9,qGNP9,and qPL9,co-localizing on chromosome 9,likely correspond to the known gene DEP1.Importantly,qGN6 and qBNS6.2 in a co-localization region were identified as novel QTL,and their Liaoxing 1 alleles had a positive effect.Several RILs with the QTL allele combinations qGD9/qPL9/qGNP9 and qGN6/qBNS6.2 showed greater GN.Further investigation of the putative gene underlying qGN6/qBNS6.2 would shed light on the molecular mechanism of JSR.

Analysis of parental genetic diversity and its impact on grain yield and quality of japonica hybrid rice in northern China

The relationship between parental genetic differences and the quality and yield of japonica hybrid rice strongly influences japonica hybrid rice breeding.In this study,137 parental lines of japonica hybrid rice were genotyped using 8 K rice SNP-Chips to characterize their genetic diversity,population structure,and indica-genotype proportion.The genetic diversity of total parental lines averaged 0.264,with values of0.287 for restorer lines and 0.148 for the sterile lines.The introduction of indica lineage increased the genetic diversity of restorer lines relative to that of sterile lines.By model-based population structure analysis,the 137 lines were divided into 14 groups.According to the grouping results,eight restorer lines and five sterile lines were selected from different groups for cross breeding,yielding 40 japonica hybrid rice combinations(F1).Investigation of the yield and quality of these combinations showed that highyield combinations could be obtained by increasing parental genetic distance to 0.8–0.9,a result accomplished largely by the introduction of indica genomic components of restorer lines.To further improve grain quality,the genetic distance between parents should be reduced to 0.4–0.5,suggesting an indicagenotype proportion of 30%–40%for restorer lines.This study may provide a reference for breeding of japonica hybrid rice.

Direct observation of the Mpemba effect with water:Probe the mysterious heat transfer

The Mpemba effect is one of the most perplexing puzzles in nature.Although it has been discussed extensively,direct observation of the Mpemba effect is extremely challenging and rare.Herein,we report the first systematic study of the Mpemba effect with water and clearly point out the conditions required for the observation of the Mpemba effect.The results demonstrate that hot water usually has a faster cooling rate than cold water.The initial temperature,temperature difference,shape of the container,and water volume influence the heat exchange and the cooling process.Owing to the influential factors of heat exchange,the Mpemba effect can only be observed under specific conditions.This work helps to clarify doubts and confusion about the Mpemba effect and can offer alternative strategies for energy storage and transfer materials.

新型环境友好绿色增塑剂的分子设计

增塑剂是塑料加工助剂中用量最大的品种,可以有效改善其加工性能,经济和社会意义重大.本文从分子设计的角度,总结了新型环境友好绿色增塑剂的研究进展.首先剖析了增塑剂的工作原理,着重讨论了润滑理论、凝胶理论和自由体积理论;然后分析了目前主要的商业化增塑剂的优缺点,尤其是增塑剂中最重要的邻苯二甲酸酯类增塑剂.由于邻苯二甲酸酯类增塑剂的毒副作用、对人类健康和环境的影响,在许多国家和地区已被限制使用,新型绿色环保增塑剂逐渐取代石油基增塑剂是未来塑料工业发展的必然趋势.本文总结了大豆油、蓖麻油等植物油基增塑剂的最新研究成果;阐述了己二酸基、ε-己内酯基等超支化聚酯增塑剂的结构特点与性能优点.举例介绍了基于腰果酚、废弃食用油、乳酸、松香、酒石酸等的增塑剂的设计与应用.最后,分析了增塑剂的化学结构与性能之间的关系,提出了通过分子设计,提高增塑剂性能的思路,并对增塑剂未来的研究和发展趋势进行了展望.

SARS-CoV-2-specific CD4^(+)T cells are associated with long-term persistence of neutralizing antibodies

Understanding the decay and maintenance of long-term SARS-CoV-2 neutralizing antibodies in infected or vaccinated people and how vaccines protect against other SARS-CoV-2 variants is critical for assessing public vaccination plans.Here,we measured different plasm antibody levels 2 and 12 months after disease onset,including anti-RBD,anti-N,total neutralizing antibodies,and two neutralizing-antibody clusters.We found that total neutralizing antibodies declined more slowly than total anti-RBD and anti-N IgG.

Investigation of the interior RC beam-column joints under monotonic antisymmetrical load

The paper presents numerical findings of reinforced concrete interior beam-column joints under monotonic antisymmetrical load.The finite element models considered compression and tension damage were calibrated by test results in terms of the load-displacement,failure modes,and strains of longitudinal steel.The emphasis was put on studying the effects of hoop reinforcement ratio in joint core and the axial compression ratio on the responses of the joints.The results show that,in addition to the truss and strut-and-tie mechanisms,the confinement mechanism also existed in the joint core.A certain amount of stirrup is not only able to enhance the confinement in joint core,undertake a part of shear force and thus to increase the shear capacity,prevent the outward buckling of steel bars in column,improve the stress distribution in joint core,delay cracking and restrain the propagation of cracks,but also to increase the yield load,decrease the yield displacement of beam and improve the joint ductility.However,excessive horizontal stirrups contribute little to the joint performance.In a certain range,larger axial compression ratio is beneficial for the joint mechanical behavior,while it is negative when axial compression ratio is too large.