Environmental DNA analysis as an emerging non-destructive method for plant biodiversity monitoring: a review

Environmental DNA (eDNA) analysis has recently transformed and modernized biodiversity monitoring. The accurate detection, and to some extent quantification, of organisms (individuals/populations/communities) in environmental samples is galvanizing eDNA as a successful cost and time-efficient biomonitoring technique. Currently, eDNA’s application to plants remains more limited in implementation and scope compared to animals and microorganisms. Thus, this review evaluates the development of eDNA-based methods for (vascular) plants, comparing its performance and power of detection with that of traditional methods, to critically evaluate and advise best practices needed for innovating plant biomonitoring. Recent advancements, standardization, and field applications of eDNA-based methods have provided enough scope to utilize it in conservation biology for numerous organisms. eDNA also has considerable potential for plants, where successful detection of invasive, endangered and rare species, and community-level interpretations have provided proof-of-concept. Monitoring methods using eDNA were found to be equal or more effective than traditional methods, however species detection increased when both the methods were coupled. Additionally, eDNA methods were found to be effective in studying species interactions, community dynamics, and even effects of anthropogenic pressure. Currently, elimination of potential obstacles (e.g., lack of relevant DNA reference libraries for plants) and the development of user-friendly protocols would greatly contribute to comprehensive eDNA-based plant monitoring programs. This is particularly needed in the data-depauperate tropics and for some less-concern plant groups. We further advocate it may be valuable to couple traditional methods with eDNA approaches, as the former is often cheaper and methodologically more straightforward, while the latter offers a non-destructive approach with the ability to identify plants in situations where morphological identification is difficult or impossible. Furthermore, in order to make a global platform for eDNA, governmental and academic-industrial collaborations are essential to make eDNA surveys a broadly adopted and implemented, rapid, cost-effective, and non-invasive plant monitoring approach.