Abstract
BackgroundStudies 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.ResultsHere, 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.ConclusionsUsing 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.
Highlights
Studies of leaf shape development and plant stature have made important contributions to the fields of plant breeding and developmental biology
Some microRNAs that can recognize the START domain of HD-ZIP Class III HOMEODOMAIN LEUCINE-ZIPPER (III) family genes, such as miRNA165 and miRNA166, may cause leaf curling by regulating HD-ZIP III family gene expression [11, 22,23,24]. miRNA160 regulates leaf curling by controlling the expressions of auxin-responsive genes ARF10 and ARF17 [25, 26]. miRNA164 affects the development of leaf margins by regulating the expression of the CUC1 gene, which may lead to a curled leaf phenotype [27]
A novel pure accession with up-curled leaves and a semi-dwarf stature found in oilseed rape breeding was used for investigation of the mutated leaf and plant type trait
Summary
Studies of leaf shape development and plant stature have made important contributions to the fields of plant breeding and developmental biology. Research on leaf morphology and plant stature is important in the fields of plant developmental biology and crop genetic improvement. The activity of auxin response factors (ARFs) affects the mutual antagonism between HD-ZIP IIIs and KANADI that regulates leaf development. The UCU1 gene encoding the SHAGGY/GSK3 protein involved in the signal transduction of auxin and BR can lead to downcurled leaves and short stature phenotypes [21]. MiRNA160 regulates leaf curling by controlling the expressions of auxin-responsive genes ARF10 and ARF17 [25, 26]. MiRNA164 affects the development of leaf margins by regulating the expression of the CUC1 gene, which may lead to a curled leaf phenotype [27] Some microRNAs that can recognize the START domain of HD-ZIP III family genes, such as miRNA165 and miRNA166, may cause leaf curling by regulating HD-ZIP III family gene expression [11, 22,23,24]. miRNA160 regulates leaf curling by controlling the expressions of auxin-responsive genes ARF10 and ARF17 [25, 26]. miRNA164 affects the development of leaf margins by regulating the expression of the CUC1 gene, which may lead to a curled leaf phenotype [27]
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