Zhengying Cao

Huazhong Agricultural University, Wu-han-shih, Hubei, China

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Publications (3)8.8 Total impact

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    ABSTRACT: Seed oil production in oilseed rape is greatly affected by the temperature during seed maturation. However, the molecular mechanism of the interaction between genotype and temperature in seed maturation remains largely unknown. We developed two near-isogenic lines (NIL-9 and NIL-1), differing mainly at a QTL region influencing oil content on Brassica napus chromosome C2 (qOC.C2.2) under high temperature during seed maturation. The NILs were treated under different temperatures in a growth chamber after flowering. RNA from developing seeds was extracted on the 25th day after flowering (DAF), and transcriptomes were determined by microarray analysis. Statistical analysis indicated that genotype, temperature, and the interaction between genotype and temperature (G × T) all significantly affected the expression of the genes in the 25 DAF seeds, resulting in 4,982, 19,111, and 839 differentially expressed unisequences, respectively. NIL-9 had higher seed oil content than NIL-1 under all of the temperatures in the experiments, especially at high temperatures. A total of 39 genes, among which six are located at qOC.C2.2, were differentially expressed among the NILs regardless of temperature, indicating the core genetic divergence that was unaffected by temperature. Increasing the temperature caused a reduction in seed oil content that was accompanied by the downregulation of a number of genes associated with red light response, photosynthesis, response to gibberellic acid stimulus, and translational elongation, as well as several genes of importance in the lipid metabolism pathway. These results contribute to our knowledge of the molecular nature of QTLs and the interaction between genotype and temperature.
    No preview · Article · Feb 2012 · Theoretical and Applied Genetics
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    ABSTRACT: Association mapping has been used increasingly in natural populations with rich genetic diversity to detect DNA-based markers that are associated with important agronomic traits. Brassica napus is an important oil crop with limited genetic diversity. "New-type" B. napus that is introgressed with subgenomic components from related species has been developed to broaden the genetic basis of "traditional" B. napus. In this study, new-type B. napus lines and a collection of traditional B. napus varieties from different countries were used as two different populations to evaluate seed oil content and to determine the efficacy of association mapping by comparison with previous study of linkage mapping. Relatively rich genetic diversity, but a higher level of linkage disequilibrium was observed in the new-type B. napus as compared with the traditional B. napus. Similarly, a larger variation in oil content and a greater number of associated markers were detected in the population of new-type B. napus. Meanwhile, more than half of the genetic loci, to which the associated markers corresponded, were located within the quantitative trait loci intervals identified previously in linkage mapping experiments, which demonstrated the power of association mapping in B. napus.
    Preview · Article · Nov 2010 · Genome
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    ABSTRACT: The history of canola breeding began with the discovery of germplasm with low erucic acid content in seeds of spring forage cultivar in the 1950's. FAE1 mutations led to a dramatic decrease of the seed erucic acid content in Arabidopsis thaliana. The products of the two FAE1 loci, BnA8.FAE1 and BnC3.FAE1, showed additive effects to the level of erucic acid content in oilseed rape. Previous research believed that the pleiotropy of FAE1 was responsible for the decrease in seed oil content along with the reduction of seed erucic acid content in the modern cultivars. TN DH population was developed from a canola cultivar Tapidor and a Chinese traditional cultivar Ningyou7. The population had been tested in 10 and 11 environments to map QTLs for the erucic acid content and oil content in seeds. As the map resolution increased, a novel QTL for seed erucic acid content was revealed, after Meta-analysis, 7 cM away from the most significant seed erucic acid content QTL where BnA8.FAE1 is located. Seven independent QTLs for seed oil content (qOC) were detected around the two seed erucic acid content QTLs (qEA) across 39.20 cM on linkage group A8. Two of the qOCs co-localized with the two qEAs, respectively, and were detected in a single environment. The other five qOCs were detected in 10 of 11 environments independent of qEAs. Alleles from Tapidor in all the QTLs at the 0-39.20 cM region contributed negative effects to either erucic acid content or oil content in seeds. Parallel, genotyping showed that on 5 of the 7 QTLs regions, Tapidor alleles had the same genotypes with that in 'Liho', the original low seed erucic acid content source. Through rounds of crossbreeding with oil-cropped cultivars and intensive selection for multi generations, Tapidor still had the inferior alleles for low seed oil content from 'Liho', the forage rape. This showed a strong linkage drag of low seed oil content, which was controlled by the five qEA-independent qOCs, with low seed erucic acid content. Ninety cultivars of B. napus from 8 countries were used to analyze the genetic drag with 9 molecular markers located in the QTL confidence intervals (24.04 cM) on linkage group A8. It was noticed that more than 46% of the cultivars with low seed erucic acid content trait remained the genotype of low seed oil content at least in one locus. Backcross and marker-assisted selection could break the genetic drag between the low oil content and erucic acid in seeds in the process for breeding modern high seed oil content canola cultivars.
    Full-text · Article · Apr 2010 · Journal of Genetics and Genomics