Tandem Expression of a Mobile RNA and Its RNA-Binding Protein(s) Enhances Tuber Productivity in Potato

A significant number of discoveries in past two decades have established the importance of long-distance signaling in controlling plant growth, development, and biotic and abiotic stress responses. Numerous mobile signals, such as mRNAs, proteins, including RNA-binding proteins, small RNAs, sugars, and phytohormones, are shown to regulate various agronomic traits such as flowering, fruit, seed development, and tuberization. Potato is a classic model tuber crop, and several mobile signals are known to govern tuber development. However, it is unknown if these mobile signals have any synergistic effects on potato crop improvement. Here, we employed a simple innovative strategy to test the cumulative effects of a key mobile RNA, StBEL5, and its RNA-binding proteins, StPTB1, and -6 on tuber productivity of two potato cultivars, Solanum tuberosum cv. Désirée and subspecies andigena, using a multi-gene stacking approach. In this approach, the coding sequences of StBEL5 and StPTB1/6 are driven by their respective native promoters to efficiently achieve targeted expression in phloem for monitoring tuber productivity. We demonstrate that this strategy resulted in earliness for tuberization and enhanced tuber productivity by 2-4 folds under growth chamber, greenhouse, and field conditions. This multi-gene stacking approach could be adopted to other crops, whose agronomic traits are governed by mobile macromolecules, expanding the possibilities to develop crops with improved traits and enhanced yields.