Discovering Candidate Chromosomal Regions Linked to Kernel Size-Related Traits via QTL Mapping and Bulked Sample Analysis in Maize

Kernel size-related traits,including kernel length,kernel width,and kernel thickness,are critical components in determining yield and kernel quality in maize(Zea mays L.).Dissecting the phenotypic characteristics of these traits,and discovering the candidate chromosomal regions for these traits,are of potential importance for maize yield and quality improvement.In this study,a total of 139 F2:3 family lines derived from EHel and B73,a distinct line with extremely low ear height(EHel),was used for phenotyping and QTL mapping of three kernel sizerelated traits,including 10-kernel length(KL),10-kernel width(KWid),and 10-kernel thickness(KT).The results showed that only one QTL for KWid,i.e.,qKWid9 on Chr9,with a phenotypic variation explained(PVE)of 13.4%was detected between SNPs of AX-86298371 and AX-86298372,while no QTLs were detected for KL and KT across all 10 chromosomes.Four bulked groups of family lines,i.e.,Groups I to IV,were constructed with F2:3 family lines according to the phenotypic comparisons of KWid between EHel and B73.Among these four groups,Group I possessed a significantly lower KWid than EHel(P=0.0455),Group II was similar to EHel(P=0.34),while both Group III and Group IV were statistically higher than EHel(P<0.05).Besides,except Group IV exhibited a similar KWid to B73(P=0.11),KWid of Groups I to III were statistically lower than B73(P<0.00).By comparing the bulked genotypes of the four groups to EHel and B73,a stable chromosomal region on Chr9 between SNPs of AX-86298372 to AX-86263154,entirely covered by qKWid9,was identified to link KWid with the positive allele of increasing phenotypic effect to KWid from B73,similar to that of qKWid9.A large amount of enzyme activity and macromolecule binding-related genes were annotated within this chromosomal region,suggesting qKWid9 as a potential QTL for KWid in maize.

A Review of Microplastics in China Marine Waters

Microplastics(<5 mm)are ubiquitous in the environment and can pose potential danger to the ecosystem and even human health.As the sink of microplastics,the ocean,especially the densely populated coastal area,has become a hotspot for research on microplastic pollution.In the last decade,the research of marine microplastics has been rapidly increasing in China.This review summarized the microplastic research conducted in China marine waters so far,and introduced the trends and progress of microplastic research in the four seas along the coast of China.We reviewed and compared the current sampling,extraction,and identification methodologies of China's microplastic research.According to the sampling method,the 30 reviewed studies were separated into two categories,trawl sampling and bulk sampling,to summarize relevant data,including abundance,sizes,shapes,colors and polymer types of microplastics.The main results showed that the distribution of microplastics in China's marine environment varied significantly,with offshore mariculture zones and the South China Sea being the most contaminated areas.Transparent,granules(or pellets)and fibers were the most dominant microplastic colors and shapes,and the size of microplastics was influenced significantly by the sampling method.Polyethylene(PE),polypropylene(PP)and polystyrene(PS)were the most common polymer types found in the China Sea,accounting for 49.96%,29.97%,and 12.38%of the total studies,respectively.Compared with other global data,China's coastal microplastic pollution is at an intermediate level and does not seem to be a major microplastic pollution source.

eQTL studies: from bulk tissues to single cells

An expression quantitative trait locus (eQTL) is a chromosomal region where genetic variants are associated with the expression levels of specific genes that can be both nearby or distant. The identifications of eQTLs for different tissues, cell types, and contexts have led to a better understanding of the dynamic regulations of gene expressions and implications of functional genes and variants for complex traits and diseases. Although most eQTL studies have been performed on data collected from bulk tissues, recent studies have demonstrated the importance of cell-type-specific and context-dependent gene regulations in biological processes and disease mechanisms. In this review, we discuss statistical methods that have been developed to enable the detection of cell-type-specific and context-dependent eQTLs from bulk tissues, purified cell types, and single cells. We also discuss the limitations of the current methods and future research opportunities.