“De novo domestication: A key to enhance the pace of plant breeding”

 

  Major crops were first domesticated about 12,000 years ago. Over 2500 plant species are thought to have been domesticated or partially domesticated for use as food. Three primary crops—rice, wheat, and maize—provide 60% of the calories consumed by people today, despite only 20 plant species accounting for 90% of the world's calories. Other under-utilized crops that have the potential to address food security challenges have lost ground due to the focus on the big three commercial and agricultural crops. The global food supply becomes more homogeneous as Green Revolution technologies are promoted. De novo domestication of wild or semi-wild plants through genetic mutation of the homologous domestication genes is the second path for future crop design, which is faster than improving present well-cultivated crops through traditional breeding3.

De novo domestication is an innovative strategy proposed for breeding new crop species where domestication genes are introduced into non-domesticated and semi-domesticated plants2. In this approach, crop wild relatives or semi- wild plants are made to acquire desirable domestication traits while their inherent desired phenotypes such as resilience to biotic and abiotic conditions are maintained. Although the traditional method of domesticating wild plants is still an option towards the creation of new crops, the recent development of the CRISPR-Cas 9 technology enables a rapid de novo domestication of wild plants. The de novo domestication has the potential to capitalize on desirable traits of wild plants, while it avoids the lengthy crossings and selections of naturally occurring genetic mutations required for traditional domestication and hence increases the pace of plant breeding.

Domestication of wild tomato Solanum pimpinellifolium is accelerated by editing genes related to day-length sensitivity, shoot architecture, flower and fruit production and nutrient content using multiplex CRISPR-Cas 9 technology1.Polyploidization of rice has long been desirable because of genome buffering, vigorousness, and environmental robustness. Thus, de novo domestication of wild allotetraploid rice is desirable. With these resources, six agronomically important traits could be rapidly improved by editing Oryza alta homologs of the genes controlling these traits in diploid rice4.

The advent of next generation genome editing tools like prime editing and base editing has the ability to replace a single nucleotide with greater precision and does not involve any insertion or deletion of a gene in coming years. This will lead to by-pass of the regulatory affairs and minimize the concerns related to public safety and health. In the future, these different de novo domestication strategies can revolutionize global agriculture by overcoming all the current drawbacks and fulfil the task of global food security.

References:

1. LI, T., YANG, X., YU, Y., SI, X., ZHAI, X., ZHANG, H., DONG, W., GAO, C. AND XU, C., 2018. Domestication of wild tomato is accelerated by genome editing. Nat. Biotechnol., 36(12): 1160-1163.

2. LUO, G., NAJAFI, J., CORREIA, P.M., TRINH, M.D.L., CHAPMAN, E.A., ØSTERBERG, J.T., THOMSEN, H.C., PEDAS, P.R., LARSON, S., GAO, C. AND POLAND, J., 2022, Accelerated domestication of new crops: Yield is key. Plant Cell Physiol., 63 (11): 1624–1640.

3. TIAN, Z., WANG, J.W., LI, J. AND HAN, B., 2021, Designing future crops: challenges and strategies for sustainable agriculture. Plant J., 105 (5): 1165-1178.

4. YU, H., LIN, T., MENG, X., DU, H., ZHANG, J., LIU, G., CHEN, M., JING, Y., KOU, L., LI, X. AND GAO, Q., 2021, A route to de novo domestication of wild allotetraploid rice. Cell, 184 (5): 1156-117.