Novel tools for delivering DNA, RNA, and protein to plants have drawn interest recently due to the success of drug delivery tools in clinical applications. Reports of novel delivery tools for plant biotechnology, such as nanomaterials, are emerging rapidly yet challenges remain and some pitfalls have surfaced. In mammalian cells, the field of drug delivery is relatively mature; best practices for developing and validating novel delivery tools are well-established and pitfalls are well-documented. Notably, delivery tools originally developed in mammalian cells are not generically applicable to plants. While mammalian literature provides a starting point, plants pose a distinct challenge, requiring development of delivery tools specifically for plants due to their unique tissue structures, metabolic/genomic complexity, and cellular morphology. Similarly, distinct pitfalls unique to developing delivery tools for plants have emerged yet are not widely documented. We discuss pitfalls observed in literature or experienced in our efforts to develop delivery tools for plants. In particular, we discuss the challenge of establishing the biological location of delivery tools, urge caution in the use of fluorescent reporters, and point out potential pathways for false positive assessment of delivery tool success. As a demonstration of an attempt to address some of these challenges, we describe a fluorescence complementation reporter system recently developed to aid in assessing the biological location of delivery tools. We demonstrate this reporter system provides unambiguous quantification of delivery events to plants enabling direct comparison of delivery tool efficiency. Furthermore, with this reporter system, we identify efficient tools for the direct delivery of proteins to plants, specifically demonstrating delivery of Lifeact peptide and WUSCHEL transcription factor. Discussion of pitfalls and novel methods to address pitfalls in the development of tools for plant biotechnology will strengthen this nascent field towards opening new avenues for engineering plant physiology.
