Abstract:

The fruit morphology of fingered citron（Citrus medica L. var. sarcodactylis Swingle）was
tracked from the stage of flower primodium to mature fruit by super depth of field microscope and
scanning electron microscope. It was found that fingered citron fruit fingers were originated from the
ovary rather than stigma. Meanwhile，CmsSUN20，CmsOFP7，CmsOFP12 and CmsYABBY5 were isolated
from fingered citron，which cDNA sequence showed 95% identity with those of sweet orange，as well as
the specific homologous relationships with sweet orange. Furthermore，the phylogenetic tree indicated that
they were clustered with sweet orange in one group，respectively. The expression levels of those four genes
in different tissues（leaf，petal，pistil and stamen）were analyzed by quantitative real-time PCR between
the two accessions. CmsSUN20 mRNA levels in fingered citron pistil were significantly higher than that in
Xiangyuan，or named as citron（C. medica L.），while slightly different in other tissues. This result indicated that CmsSUN20 gene may be associated with the fruit development of fingered citron.
CmsYABBY5 gene was highly expressed in both pistil and stamen of fingered citron，but lowly expressed
in leaf，implying CmsYABBY5 play a role during the development of pistil and stamen in fingered citron.
Both the expression levels of CmsOFP7 and CmsOFP12 were higher in four tissues of fingered citron
than those in Xiangyuan，indicating the two genes have insignificant contribution to fruit shaping.

Key words: fingered citron, fruit morphology, fruit shaping, CmsSUN20, CmsOFP7, CmsOFP12, CmsYABBY5