Foundation parents (FPs) play an irreplaceable role in maize breeding practices. Maize white spot (MWS) is an important disease in Southwest China that always seriously reduces production. However, ...knowledge about the genetic mechanism of MWS resistance is limited. In this paper, a panel of 143 elite lines were collected and genotyped by using the MaizeSNP50 chip with approximately 60,000 single nucleotide polymorphisms (SNPs) and evaluated for resistance to MWS among 3 environments, and a genome-wide association study (GWAS) and transcriptome analysis were integrated to reveal the function of the identity-by-descent (IBD) segments for MWS. The results showed that (1) 225 IBD segments were identified only in the FP QB512, 192 were found only in the FP QR273 and 197 were found only in the FP HCL645. (2) The GWAS results showed that 15 common quantitative trait nucleotides (QTNs) were associated with MWS. Interestingly, SYN10137 and PZA00131.14 were in the IBD segments of QB512, and the SYN10137-PZA00131.14 region existed in more than 58% of QR273's descendants. (3) By integrating the GWAS and transcriptome analysis, Zm00001d031875 was found to located in the region of SYN10137-PZA00131.14. These results provide some new insights for the detection of MWS's genetic variation mechanisms.
Plant architecture is one of the key factors affecting maize yield formation and can be divided into secondary traits, such as plant height (PH), ear height (EH), and leaf number (LN). It is a viable ...approach for exploiting genetic resources to improve plant density. In this study, one natural panel of 226 inbred lines and 150 family lines derived from the offspring of T32 crossed with Qi319 were genotyped by using the MaizeSNP50 chip and the genotyping by sequence (GBS) method and phenotyped under three different environments. Based on the results, a genome-wide association study (GWAS) and linkage mapping were analyzed by using the MLM and ICIM models, respectively. The results showed that 120 QTNs (quantitative trait nucleotides) and 32 QTL (quantitative trait loci) related to plant architecture were identified, including four QTL and 40 QTNs of PH, eight QTL and 41 QTNs of EH, and 20 QTL and 39 QTNs of LN. One dominant QTL, qLN7-2, was identified in the Zhangye environment. Six QTNs were commonly identified to be related to PH, EH, and LN in different environments. The candidate gene analysis revealed that
was involved in regulating plant architecture traits through the autophagy pathway, and
was predicted to interact with the male sterility-related gene ms26. These results provide abundant genetic resources for improving maize plant architecture traits by using approaches to biological breeding.
Maize (
) inbred lines vary greatly in flowering time, but the genetic basis of this variation is unknown. In this study, three maize flowering-related traits (DTT, days to tasselling; DTP, days to ...pollen shed; DTS, days to silking) were evaluated with an association panel consisting of 226 maize inbred lines and an F
population with 120 offspring from a cross between the T32 and Qi319 lines in different environments. A total of 82 significant single nucleotide polymorphisms (SNPs) and 117 candidate genes were identified by genome-wide association analysis. Twenty-one quantitative trait loci (QTLs) and 65 candidate genes were found for maize flowering time by linkage analysis with the constructed high-density genetic map. Transcriptome analysis was performed for Qi319, which is an early-maturing inbred line, and T32, which is a late-maturing inbred line, in two different environments. Compared with T32, Qi319 showed upregulation of 3815 genes and downregulation of 3906 genes. By integrating a genome-wide association study (GWAS), linkage analysis and transcriptome analysis, 25 important candidate genes for maize flowering time were identified. Together, our results provide an important resource and a foundation for an enhanced understanding of flowering time in maize.
The Suwan population is a well-known maize germplasm that has greatly contributed to the development of maize breeding in tropical and subtropical regions, especially in southern China. Inbred lines ...derived from the Suwan population always contain stronger resistance and extensive adaptability in different environments. To evaluate the genetic character of inbred lines derived from the Suwan population, a panel including 226 inbred line derived from the Suwan population and temperate resources was assembled and genotyped by using MaizeSNP50 BeadChip, which contained 56,110 genome-wide single nucleotide polymorphism (SNP) markers. This panel contained 98 temperate inbred line and 128 lines derived from the Suwan population.
The results showed that high genetic diversity was found, with PIC and GD to be 0.67 and 0.60, respectively. In addition, two novel subgroups were identified, with representative inbred lines as HCL645 and Ki32, respectively. One acknowledged heterotic group of Iowa Stiff Stalk Synthetic (SS) was also identified in this study. This study can provide some additional scientific evidence for heterotic group division and use in maize. Additionally, lower linkage disequilibrium (LD) levels and weaker genetic relationships were found, with an average LD level of 41.15 kb that varied from 3.5 to 96 kb. A total of 82.8% of paired relative kinships ranged from 0.05 to 0.28.
These results would not only facilitate maize breeding practices in tropical and subtropical regions, but also revealed that this panel can be used in dissecting the genetic basis of complex quantitative traits' variations by using genome-wide association studies (GWAS).
Plant architecture-related traits are important in breeding maize (
Zea mays L.
). Suwan maize germplasm has been widely used in tropical/subtropical regions because of its abundant genetic diversity ...compared to temperate germplasm. To investigate the influence of the genetic base on the detection of quantitative trait loci (QTLs) controlling plant architecture-related traits, a population of 150 F
2:3
progeny derived from ZHL908 and HCL645 were developed and genotyped using the genotyping by sequencing (GBS) method. Through inclusive composite interval mapping using 5636 SNP markers, a total of 25 QTL-controlling plant architecture-related traits were identified. Seventeen QTLs had been previously reported, which may be important in future MAS breeding. Eight new QTLs were reported for the first time in this study. Of the 25 QTLs, 7 QTLs were related to plant height (PH), 4 QTLs were related to ear height (EH), 4 QTLs were related to leaf number (LN), 5 QTLs were related to tassel length (TL), and 5 QTLs were related to tassel primary branch number (TPBN). Four plant architectural trait-related genes,
sparse inflorescence1
,
ramosa3
,
dwarf1
, and
zea floricaula/leafy1
, were found to be located in
qLN4
,
qTL5
,
qTPBN1
and
qTPBN5
, respectively. These results not only provide new insights into the genetic research investigating maize plant architecture variation but also provide molecular evidence that may enable the improvement of Suwan germplasm in modern maize breeding.
Suwan germplasm plays important roles in maize breeding in tropical/subtropical regions, especially in southern China. To analyze the genetic characteristics of Suwan maize germplasm, one panel of 73 ...lines derived from the Suwan population and temperate resources were collected and genotyped using 56,110 single‐nucleotide polymorphism (SNP) markers. The results revealed four subgroups, namely, QR273, Ki32, HCL645, and PH4CV, with an average genetic distance of 0.304, varying from 0.001 to 0.370. In addition, many identical‐by‐descent (IBD) segments were found among Suwan germplasms and their descendants, of which 78 segments were detected only in the QR273 subgroup, 18 segments were detected only in the Ki32 subgroup, 53 and 11 segments were detected only in the PH4CV and the HCL645 subgroup, respectively. Pairwise comparisons showed that 13 segments were common between the QR273 and Ki32 subgroups, 5 segments were common between the QR273 and HCL645 subgroups, 26 segments were common between the QR273 and PH4CV subgroups. Five and 14 segments were common between the Ki32 versus HCL645 subgroups and Ki32 versus PH4CV subgroups. Three segments were commonly detected in the Ki32, QR273, and HCL645 subgroups. Candidate gene analysis showed that 132 genes were located in these segments, wherein seven new candidate genes were associated with flower time (FT)‐related traits, which were located in the IBD segments of QR273 or HCL645. Zm00001d033130_T005 and Zm00001d013768_T001 were located in the IBD segments specific to the QR273 subgroup. These two genes function in cell differentiation and flower development and would be very important for the phenotypic variations of the given FP subgroups. These results provide new insights and scientific proof for dissecting the genetic basis of complex traits and the utilization of Suwan germplasm in future maize breeding.
Selecting elite silage specific variety was important for modern animal husbandry development and agricultural production. In this paper, six forage quality related physiology traits were evaluated ...by using chemical detection method, the difference between maize silage and hybrid giant napier (pennisetum hydridum) were analyzed. Results showed that, maize showed better performance than that of hybrid giant napier, with average protein content of 8.54% VS 7.48%, starch content of 11.18% VS 7.90%, soluble sugar content of 4.09% VS 2.90%, and IVOMD of 35.23% VS 34.94%, respectively. No significant differences were found for NDF content and ADF content between maize and hybrid giant napier. In addition, QQ446 showed better performance than that of JY818, with higher IVOMD of 35.50% VS 34.95%, higher protein content of 8.60% VS 8.48%, higher starch content of 11.82% VS 10.53%, and lower ADF content of 32.86% VS 37.43%. These results proved that, QQ446 was the elite silage specific variety, it contained much more forage advantages, and could be widely used in future animal husbandry development and agricultural production.
The reaction behavior of oil sand from Inner Mongolia（China） were studied in a fluidizedbed pyrolysis process,and a comparative study was conducted on the properties of the liquid products obtained ...through fluidized-bed pyrolysis of oil sand and the native bitumen obtained by solvent extraction.The results indicated that the fluidized-bed pyrolysis,a feasible carbon rejection process,can be used to upgrade oil sand.The reaction temperature and time were found to be the key operating parameters affecting the product distribution and yields in fluidized-bed pyrolysis of oil sand.The optimal temperature was 490℃ and the most suitable reaction time was 5 min.Under these operation conditions,the maximum yield of liquid product was 80wt%.In addition,the pyrolysis kinetics of oil sand at different heating rates of 5,10,20 and 30℃/min was investigated using a thermogravimetric analyzer（TGA）.
Asthma, rhinitis and eczema (allergic or non-allergic) have increased throughout the world during the last decades, especially among children. Changes in the indoor environment are suspected to be ...important causes. China has experienced a dramatic change in indoor environmental exposures during the past two decades. However, such changes and their associations with children’s asthma and other health aspects have not been thoroughly studied. China, Children, Homes, Health (CCHH), Phase I, was a cross-sectional questionnaire survey of 48219 children 1–8 years old in 10 Chinese cities during 2010–2012. The questionnaire includes the International Study of Asthma and Allergies in Childhood (ISAAC) core health questions and additional questions regarding housing, life habits and outdoor environment. In health analyses, children aged 3–6 years old were included. The prevalences of doctor diagnosed asthma varied from 1.7% to 9.8% (mean 6.8%), a large increase from 0.91% in 1999 and 1.50% in 2000. The prevalence of wheeze, rhinitis and atopic eczema (last 12 months) varied from 13.9% to 23.7%, 24.0% to 50.8% and 4.8% to 15.8%, respectively. Taiyuan had the lowest prevalences of all illnesses and Shanghai the highest, except for wheezewhere the highest value was for Urumqi. We found (1) no obvious association between disease prevalences and ambient PM₁₀ concentrations and (2) higher prevalences of disease in humid climates with hot summers and cold winters, but with no centrally heated buildings. Associations between the diseases and economic status as indexed by Gross Domestic Product (GDP) requires further study.
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