Publications by authors named "Yungu Zhai"

3 Publications

  • Page 1 of 1

Targeted mutagenesis of EOD3 gene in Brassica napus L. regulates seed production.

J Cell Physiol 2021 Mar 25;236(3):1996-2007. Epub 2020 Aug 25.

National Key Laboratory of Crop Genetic Improvement, Huazhong Agricultural University, Wuhan, China.

Seed size and number are central to the evolutionary fitness of plants and are also crucial for seed production of crops. However, the molecular mechanisms of seed production control are poorly understood in Brassica crops. Here, we report the gene cloning, expression analysis, and functional characterization of the EOD3/CYP78A6 gene in rapeseed. BnaEOD3 has four copies located in two subgenomes, which exhibited a steady higher expression during seed development with differential expression among copies. The targeted mutations of BnaEOD3 gene were efficiently generated by stable transformation of the CRISPR/Cas9 (clustered regularly interspaced short palindromic repeat) vector. These mutations were stably transmitted to T and T generations and a large collection of homozygous mutants with combined loss-of-function alleles across four BnaEOD3 copies were created for phenotyping. All mutant T lines had shorter siliques, smaller seeds, and an increased number of seeds per silique, in which the quadrable mutants showed the most significant changes in these traits. Consequently, the seed weight per plant in the quadrable mutants increased by 13.9% on average compared with that of wild type, indicating that these BnaEOD3 copies have redundant functions in seed development in rapeseed. The phenotypes of the different allelic combinations of BnaEOD3 copies also revealed gene functional differentiation among the two subgenomes. Cytological observations indicated that the BnaEOD3 could act maternally to promote cotyledon cell expansion and proliferation to regulate seed growth in rapeseed. Collectively, our findings reveal the quantitative involvement of the different BnaEOD3 copies function in seed development, but also provided valuable resources for rapeseed breeding programs.
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http://dx.doi.org/10.1002/jcp.29986DOI Listing
March 2021

Targeted mutagenesis of BnTT8 homologs controls yellow seed coat development for effective oil production in Brassica napus L.

Plant Biotechnol J 2020 05 11;18(5):1153-1168. Epub 2019 Nov 11.

National Key Laboratory of Crop Genetic Improvement, Huazhong Agricultural University, Wuhan, China.

Yellow seed is a desirable trait with great potential for improving seed quality in Brassica crops. Unfortunately, no natural or induced yellow seed germplasms have been found in Brassica napus, an important oil crop, which likely reflects its genome complexity and the difficulty of the simultaneous random mutagenesis of multiple gene copies with functional redundancy. Here, we demonstrate the first application of CRISPR/Cas9 for creating yellow-seeded mutants in rapeseed. The targeted mutations of the BnTT8 gene were stably transmitted to successive generations, and a range of homozygous mutants with loss-of-function alleles of the target genes were obtained for phenotyping. The yellow-seeded phenotype could be recovered only in targeted mutants of both BnTT8 functional copies, indicating that the redundant roles of BnA09.TT8 and BnC09.TT8b are vital for seed colour. The BnTT8 double mutants produced seeds with elevated seed oil and protein content and altered fatty acid (FA) composition without any serious defects in the yield-related traits, making it a valuable resource for rapeseed breeding programmes. Chemical staining and histological analysis showed that the targeted mutations of BnTT8 completely blocked the proanthocyanidin (PA)-specific deposition in the seed coat. Further, transcriptomic profiling revealed that the targeted mutations of BnTT8 resulted in the broad suppression of phenylpropanoid/flavonoid biosynthesis genes, which indicated a much more complex molecular mechanism underlying seed colour formation in rapeseed than in Arabidopsis and other Brassica species. In addition, gene expression analysis revealed the possible mechanism through which BnTT8 altered the oil content and fatty acid composition in seeds.
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http://dx.doi.org/10.1111/pbi.13281DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7152602PMC
May 2020

CRISPR/Cas9-mediated genome editing reveals differences in the contribution of INDEHISCENT homologues to pod shatter resistance in Brassica napus L.

Theor Appl Genet 2019 Jul 12;132(7):2111-2123. Epub 2019 Apr 12.

National Key Laboratory of Crop Genetic Improvement, Huazhong Agricultural University, Wuhan, 430070, China.

The INDEHISCENT (IND) and ALCATRAZ (ALC) gene homologues have been reported to be essential for dehiscence of fruits in Brassica species. But their functions for pod shatter resistance in Brassica napus, an important oil crops, are not well understood. Here, we assessed the functions of these two genes in rapeseed using CRISPR/Cas9 technology. The induced mutations were stably transmitted to successive generations, and a variety of homozygous mutants with loss-of-function alleles of the target genes were obtained for phenotyping. The results showed that the function of BnIND gene is essential for pod shatter and highly conserved in Brassica species, whereas the BnALC gene appears to have limited potential for rapeseed shatter resistance. The homoeologous copies of the BnIND gene have partially redundant roles in rapeseed pod shatter, with BnA03.IND exhibiting higher contributions than BnC03.IND. Analysis of data obtained from the gene expression and sequence variations of gene copies revealed that cis-regulatory divergences alter gene expression and underlie the functional differentiation of BnIND homologues. Collectively, our results generate valuable resources for rapeseed breeding programs, and more importantly provide a strategy to improve polyploid crops.
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http://dx.doi.org/10.1007/s00122-019-03341-0DOI Listing
July 2019