A rapid and highly efficient method for transient gene expression in rice plants

Transient gene expression is an important tool for deciphering molecular functions of a gene in a very short period. It is useful for studying the intracellular localization of proteins, to uncover in-vivo protein-protein, protein-DNA and protein-RNA interactions, and to perform Co-IP, ChIP and protein activity experiments. Although this method is extensively employed for plant species like Arabidopsis and tobacco, transient expression in rice, a model monocot system, has not been widely reported. To study rice genes, transient expression experiments are performed in tobacco, Arabidopsis, onion epidermal cells or rice protoplasts as the structure of rice leaves (high wax and silica content) makes Agrobacterium-based transformation difficult. Rice protoplasts, though efficient, do not mimic the exact conditions of a plant cell and are highly susceptible to bursting. In addition, change in protein localisation or dimerization pattern in response to different stresses cannot be studied using rice protoplasts. In our study, we standardised a method for transient transformation in rice seedlings. By growing the rice seedlings at low temperature and in only Milli-Q water, we were able to overcome the barriers of waxy cuticle and high silica content. This is because low temperature reduced epicuticular wax production in rice plants and Milli-Q water removed any external source of silica, thereby, reducing its overall content in the rice seedlings. 6-day-old rice seedlings were used for co-cultivation with Agrobacterium in the presence of a medium containing Silwet® L-77, acetosyringone and glucose. Based on our study, we report that rice seedlings can be visualized 9 days after co-cultivation for transient expression in the cells of first leaf for intra-cellular localisation as well as for BiFc experiments. This method could pave the way for accelerating the pace of rice research, bringing it at par with other model plants like Arabidopsis and tobacco.

For full article: https://doi.org/10.3389/fpls.2020.584011