Resilient Crops: Learning From Desiccation-Tolerant Plants | Science

The ability of some plants to survive extreme dehydration – even for years – and then rapidly revive has long fascinated botanists. Now, as droughts become more frequent and severe due to climate change, scientists are increasingly focused on understanding the mechanisms behind this resilience, hoping to transfer these traits to vital food crops. This pursuit centers on what are commonly called “resurrection plants,” a minor group of angiosperms – flowering plants – capable of tolerating levels of desiccation that would kill most other species.

The Lazarus-Like Ability of Angiosperms

Jill Farrant, a professor of desiccation tolerance at the University of Cape Town, has dedicated over three decades to studying these remarkable plants. Her work, and that of others, suggests that the key to their survival lies in their ability to protect cellular structures and quickly resume metabolic activity when water becomes available. It’s a phenomenon observed commonly in mosses and ferns, but far less so in flowering plants. Out of an estimated 352,000 flowering plant species, only around 240 are considered resurrection plants. These plants, often found in the rocky slopes and gravelly soils of South Africa, Australia, and South America, appear to have independently evolved this ability, suggesting a common ancestral toolkit for drought response.

The process is visually striking. A resurrection plant, when deprived of water, will appear dead – its leaves brown and brittle. Though, upon rehydration, it can regreen within hours, resuming photosynthesis and essentially returning to its former state. This isn’t simply revival; it’s a complete recovery from a state of near-total dehydration.

Desiccation Tolerance: A Genetic Puzzle

Researchers are working to unravel the genetic basis of this desiccation tolerance. A growing body of evidence, outlined in a recent editorial in Frontiers in Plant Science, points to similarities in the mechanisms of desiccation tolerance between seeds and the vegetative tissues of resurrection plants. The theory proposes that these plants have essentially reactivated genetic elements typically associated with seed survival within their leaves and stems, allowing them to withstand extreme water loss.

This is significant because seeds are naturally desiccation tolerant – it’s a crucial adaptation for ensuring survival during dry periods. Understanding how resurrection plants have “switched on” these seed-specific genes in their vegetative tissues could provide valuable insights into engineering drought resistance in crops.

What Does ‘Desiccation Tolerance’ Actually Indicate?

Desiccation tolerance refers to a plant’s ability to survive extreme drying without significant damage to its cells. This involves a complex suite of physiological and biochemical adaptations. Plants achieve this by protecting their cell membranes, proteins, and DNA from damage during dehydration. They too have mechanisms to rapidly repair any damage that does occur when water is reintroduced. It’s not simply about preventing water loss; it’s about surviving the consequences of severe water loss at a cellular level.

Implications for Agriculture and Food Security

The potential implications for agriculture are substantial. As climate change intensifies, droughts are becoming more frequent and prolonged, threatening crop yields and food security worldwide. If scientists can identify the genes responsible for desiccation tolerance in resurrection plants and successfully transfer them to crops like wheat, rice, or maize, it could significantly enhance their ability to withstand drought conditions.

Farrant expresses hope that these desiccation-tolerant species can provide a blueprint for creating more resilient crops. However, it’s a complex undertaking. Simply transferring a single gene is unlikely to be sufficient. Desiccation tolerance is likely controlled by a network of genes, and understanding their interactions is crucial.

Challenges and Limitations in Transferring Tolerance

While the prospect of drought-resistant crops is promising, several challenges remain. One key hurdle is the complexity of plant genomes. Identifying the specific genes responsible for desiccation tolerance is a painstaking process. Even if these genes are identified, transferring them to crops and ensuring they function effectively in a different genetic background can be difficult.

Another consideration is the potential trade-offs. Introducing drought tolerance might come at the expense of other desirable traits, such as yield or nutritional value. Researchers need to carefully evaluate these trade-offs to ensure that the benefits of drought resistance outweigh any potential drawbacks.

The Path Forward: Research and Development

Current research efforts are focused on several key areas. These include: identifying the genes involved in desiccation tolerance, understanding the molecular mechanisms underlying this tolerance, and developing techniques for transferring these genes to crops. Researchers are also exploring the possibility of using genetic engineering and gene editing technologies to enhance drought resistance in plants.

The process is likely to be lengthy and require significant investment. However, the potential benefits – increased food security and reduced vulnerability to climate change – are substantial. Continued research and development in this area are essential to ensure a sustainable food supply for a growing global population.

Ongoing Investigations and Future Directions

The study of resurrection plants is an evolving field. Researchers are now employing advanced genomic and proteomic techniques to gain a more comprehensive understanding of the molecular mechanisms underlying desiccation tolerance. Further investigation is needed to determine the long-term effects of introducing these traits into crops and to assess their performance under real-world field conditions. Collaboration between plant biologists, geneticists, and agricultural scientists will be crucial to translate these discoveries into practical solutions for enhancing crop resilience.