On 18th April, 2018, Prof. Lu Gang's group from the Institute of Vegetable Science, published a scientific paper on line in “New Phytologist ”with the title “Evidence for a specific and critical role of mitogen-activated protein kinase 20 in uni-to-binucleate transition of microgametogenesis in tomato ”（DOI: 10.1111/nph.15150, https://nph.onlinelibrary.wiley.com/doi/full/10.1111/nph.15150) . The research concludes that SlMPK20 specifically regulates post-meiotic pollen development through modulating sugar and auxin metabolism and signaling. This study provided an important basis for elucidating the regulatory mechanism of tomato fertility.
Mitogen-activated protein kinases (MAPKs) play diverse roles in plant growth and defense. However，their potential involvement in reproductive development remains largely unknown. Tomato is one of the most important vegetable crops in the world, and also a model plant for reproductive development research. The studies have shown that tomato stamen development is controlled by multiple genes and is extremely sensitive to the external environment. Here, the present study identified a unique role of SlMPK20, a plant-specific group TDY MAPK in postmeiotic pollen development in tomato. RNAi-mediated suppression of SlMPK20 or its knockout using CRISPR/Cas9 significantly reduced or completely abolished pollen viability and seed set, respectively, without effects on maternal fertility or vegetative growth. Detailed microscopic and gene expression analyses identified the uninucleate microspore formation as the stage when SlMPK20 exerts its role in pollen development. Transcriptome analysis revealed that knock-out of SlMPK20 significantly reduced the expression of a large number of genes controlling sugar metabolism and transport as well as auxin metabolism and signaling in uninucleate anthers. Finally, protein-protein interaction assays identified SlMYB32, a homologous transcription factor of AtMYB32 required for pollen development in Arabidopsis, as a target interacted by SlMPK20. The cloning and functional analysis of the tomato fertility regulatory gene SlMPK20 provided theoretical and technical support for the establishment of tomato regulated male sterile lines.
Dr. Chen Lifei from the Institute of Vegetable Science is the first author, and Prof. Lu Gang and Dr. Ruan Yongling, Guangbiao Chair Professor of Zhejiang University, from the University of Newcastle, Australia are the corresponding authors for this paper. This work was supported by the National Natural Science Foundation of China and the Natural Science Foundation of Zhejiang Province, China.
