Gene editing to improve legume-rhizobia symbiosis in a changing climate

In the last three years, several gene editing techniques have been developed for both model and crop legumes. CRISPR-Cas9-based tools, in particular, are outpacing other comparable gene editing technologies used in legume hosts and their mi-crobial symbionts to understand the molecular basis of symbi-otic nitrogen-fixation. Gene editing has helped identify new gene functions, validate genetic screens, resolve gene redun-dancy, examine the role of tandemly duplicated genes, and investigate symbiotic signaling networks in non-model plants. In this review, we discuss the advances made in understanding the legume-rhizobia symbiosis through the use of gene editing and highlight studies conducted under varying environmental conditions. We reason that future climate-hardy legumes must be able to better integrate environmental signals with nitrogen fixation by fine-tuning long distance signaling, continuing to select efficient rhizobial partners, and adjusting their molecular circuitry to function optimally under variable light and nutrient availability and rising atmospheric carbon dioxide.

Automated summary

Several gene editing techniques, including CRISPR-Cas9-based tools, have been developed for studying legume-rhizobia symbiosis. Gene editing has played a crucial role in identifying gene functions, validating genetic screens, resolving gene redundancy, and investigating symbiotic signaling networks in non-model plants. The integration of environmental signals with nitrogen fixation for climate-hardy legumes is important for their optimal functioning under varying conditions.