AUTHOR=Zeng Bin , Wang Jianyou , Hao Qing , Yu Zhenfan , Abudukayoumu Ayimaiti , Tang Yilian , Zhang Xiangfei , Ma Xinxin 

TITLE=Identification of a Novel SBP1-Containing SCFSFB Complex in Wild Dwarf Almond (Prunus tenella)

JOURNAL=Frontiers in Genetics

VOLUME=10

YEAR=2019

URL=https://www.frontiersin.org/journals/genetics/articles/10.3389/fgene.2019.01019

DOI=10.3389/fgene.2019.01019

ISSN=1664-8021

ABSTRACT=<p>S-RNase-based gametophytic self-incompatibility (SI), in which specificities of pistil and pollen are determined by S-RNase and the S locus F-box protein, respectively, has been discovered in the Solanaceae, Plantaginaceae, and Rosaceae families, but some underlying molecular mechanisms remain elusive and controversial. Previous studies discovered SI in wild dwarf almond (<italic>Prunus tenella</italic>), and pistil S (S-RNase) and pollen S (SFB) determinant genes have been investigated. However, the SCF (SKP1–Cullin1–F-box-Rbx1) complex, which serves as an E3 ubiquitin ligase on non-self S-RNase, has not been investigated. In the current study, <italic>PetSSK1</italic> (<italic>SLF-interacting-SKP1-like1</italic>), <italic>SBP1</italic> (<italic>S-RNase binding protein 1</italic>), <italic>CUL1</italic>, and <italic>SFB</italic> genes (S-haplotype-specific F-box) were identified in an accession (ZB1) of <italic>P. tenella</italic>. Yeast two-hybrid assays revealed interactions between <italic>PetSBP1</italic> and <italic>PetCUL1</italic> and between <italic>PetSBP1</italic> and <italic>PetSFB</italic>s (<italic>SFB16</italic> and <italic>SFB17</italic>), and subsequent pull-down assays confirmed these interactions, suggesting a novel SBP1-containing SCF<sup>SFB</sup> complex in wild dwarf almond. Moreover, despite a putative interaction between <italic>PetSSK1</italic> and <italic>PetCUL1</italic>, we revealed that <italic>PetSSK1</italic> does not interact with <italic>PetSFB16</italic> or <italic>PetSFB17</italic>, and thus the canonical SSK1-containing SCF<sup>SFB</sup> complex could not be identified. This suggests a novel molecular mechanism of gametophytic SI in <italic>Prunus</italic> species.</p>