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. 2020 Jul 31;21(1):530.
doi: 10.1186/s12864-020-06947-7.

Fine mapping of the BnUC2 locus related to leaf up-curling and plant semi-dwarfing in Brassica napus

Chengwei Huang  1 , Mao Yang  1 , Danlei Shao  1 , Yangming Wang  1 , Shubei Wan  1 , Jianbo He  1 , Zuqing Meng  2 , Rongzhan Guan  3
Affiliations

Fine mapping of the BnUC2 locus related to leaf up-curling and plant semi-dwarfing in Brassica napus

Chengwei Huang et al. BMC Genomics. .

Abstract

Background: Studies of leaf shape development and plant stature have made important contributions to the fields of plant breeding and developmental biology. The optimization of leaf morphology and plant height to improve lodging resistance and photosynthetic efficiency, increase planting density and yield, and facilitate mechanized harvesting is a desirable goal in Brassica napus.

Results: Here, we investigated a B. napus germplasm resource exhibiting up-curled leaves and a semi-dwarf stature. In progeny populations derived from NJAU5737 and Zhongshuang 11 (ZS11), we found that the up-curled leaf trait was controlled by a dominant locus, BnUC2. We then fine mapped the BnUC2 locus onto an 83.19-kb interval on chromosome A05 using single nucleotide polymorphism (SNP) and simple sequence repeat (SSR) markers. We further determined that BnUC2 was a major plant height QTL that explained approximately 70% of the phenotypic variation in two BC5F3 family populations derived from NJAU5737 and ZS11. This result implies that BnUC2 was also responsible for the observed semi-dwarf stature. The fine mapping interval of BnUC2 contained five genes, two of which, BnaA05g16700D (BnaA05.IAA2) and BnaA05g16720D, were revealed by comparative sequencing to be mutated in NJAU5737. This result suggests that the candidate gene mutation (BnaA05g16700D, encoding Aux/IAA2 proteins) in the conserved Degron motif GWPPV (P63S) was responsible for the BnUC2 locus. In addition, investigation of agronomic traits in a segregated population indicated that plant height, main inflorescence length, and branching height were significantly reduced by BnUC2, whereas yield was not significantly altered. The determination of the photosynthetic efficiency showed that the BnUC2 locus was beneficial to improve the photosynthetic efficiency. Our findings may provide an effective foundation for plant type breeding in B. napus.

Conclusions: Using SNP and SSR markers, a dominant locus (BnUC2) related to up-curled leaves and semi-dwarf stature in B. napus has been fine mapped onto an 83.19-kb interval of chromosome A05 containing five genes. The BnaA05.IAA2 is inferred to be the candidate gene responsible for the BnUC2 locus.

Keywords: Brassica napus; Gene mapping; Semi-dwarf; Simple sequence repeat; Single nucleotide polymorphism; Up-curled leaves.

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Conflict of interest statement

The authors declare that they have no competing interests.

Figures

Fig. 1
Fig. 1
Performance of NJAU5737, (NJAU5737 × ZS11) F1 and ZS11. a Leaf of NJAU5737 (left), (NJAU5737 × ZS11) F1 (middle) and ZS11 (right) at the seedling stage. b Seedling of NJAU5737 (left), (NJAU5737 × ZS11) F1 (middle) and ZS11 (right). c NJAU5737 (left), (NJAU5737 × ZS11) F1 (middle) and ZS11 (right) at mature stage
Fig. 2
Fig. 2
Genetic map and physical map of the BnUC2 locus. a. The primary genetic map of BnUC2 locus, the red indicates the mapping interval. b. Fine mapping of BnUC2 locus. c. The physical map of BnUC2 locus, the unit is Mb
Fig. 3
Fig. 3
Experimental results of polymorphic marker BnaA05–442. Marker scan with progeny BC5F3 populations derived from the parents ZS11 and NJAU5737 was conducted. P1 and P2 indicates PCR products from the parents ZS11 and NJAU5737 plants, respectively. The number 3, 4, 5, 6, 8, 9 and 10 denote the PCR products from heterozygous plants with up-curled leaves, and 1 denotes the PCR products from homozygous plants with up-curled leaves, and 2 and 7 denote the PCR products from homozygous plants with flat leaves. Full-length, original blots image was presented in additional file 6: Fig. S3
Fig. 4
Fig. 4
Amino acid sequence alignment of BnaA05g16700D (BnaA05.IAA2) in ZS11 and NJAU5737. Four conserved domain of BnaA05g16700D were designated as I, II, III and IV, indicated by red underline
See this image and copyright information in PMC

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