Overexpression of the Solanum nigrum F-box Gene SnUFO2 Alters Inflorescence Morphogenesis
ZHANG Ying-Ying*, WEI Wen-Quan*, ZHU Sui-Min, CUI Min-Long, PIAO Chun-Lan**
College of Horticulture/Key Laboratory of Quality and Safety Control for Subtropical Fruit and Vegetable, Ministry of Agriculture, Zhejiang A&F University, Hangzhou 311300, China
Abstract：Solanum nigrum (Solanaceae) is an important plant for both food and medicine. The F-box family gene UNUSUAL FLORAL ORGANS (UFO) plays a critical role in the regulation of the inflorescence structure establishment and floral organ development. Previous study showed that overexpression of a truncated SnUFO2 gene (lacking 23 amino acids at the C-terminus) leads to abnormal floral organ development. To further investigate the function of SnUFO2 in flower development, this study conducted spatiotemporal expression analysis of SnUFO2, creating overexpression transgenic lines, morphological observations, and detecting the expression of class B floral organ identity genes. Spatiotemporal expression analysis showed that SnUFO2 was specifically expressed in the apical meristem at the flowering stage. qPCR analysis revealed that SnUFO2 was expressed in the sepals, petals, stamens, and pistils of early flower buds, and its expression in sepals and petals was significantly higher than leaves, stamens and carpels (P<0.05). Morphological observations showed that transgenic S. nigrum plants overexpressing SnUFO2 exhibited dwarfism, early flowering, conversion of cyme inflorescences into single flowers, petaloid sepals, and carpels transformed into stamen-carpel fused organs. Furthermore, qPCR analysis revealed that the expression levels of the B-class floral organ identity genes SnGLOBOSA (SnGLO), SnPISTILLATA (SnPI28), SnDEFICIENS (SnDEF), and SnDEFICIENS 64 (SnDEF64) were significantly upregulated in the transgenic flowers (P<0.05), implying that SnUFO2 played a conserved role in inflorescence architecture and floral organ development by positively regulating expression of the B-class floral organ identity genes. This study provides a theoretical reference and research ideas for flower and fruit thinning using biotechnology approaches.
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