CRISPR/Cas9 gene editing in legume crops: Opportunities and challenges

Abstract

Legumes are an excellent source of proteins and health‐promoting phytochemicals. Recognizing their importance in human nutrition and sustainable agricultural production, significant efforts are currently being made to accelerate genetic gain related to yield, stress resilience, and nutritional quality. Recent increases in genomic resources for multiple legume crops have laid a solid foundation for application of transformative breeding technologies such as genomic selection and genome editing for crop improvement. In this review, we focus on the recent plant‐specific advances in CRISPR/Cas9‐based gene editing technology and discuss the challenges and opportunities to harnessing this innovative technology for targeted improvement of traits in legume crops. Gene‐editing methods have been successfully established for soybean, cowpea, chickpea, and model legumes such as Medicago truncatula and Lotus japonicus. However, the recalcitrance of other legumes to in vitro gene transfer and regeneration has posed a serious challenge to application of gene editing. We discuss various modifications to in vitro culture methods, in terms of the choice of explant, media composition, and DNA delivery and gene‐editing detection methods that can potentially improve the rate of transformation and regeneration of whole plant in legume crops. Although gene‐editing technology can bring enormous benefits to legume breeding, regulatory hurdles are a cause for serious concern. We compare the regulatory environments existing in the European Union and the United States of America. A favorable regulatory framework and public acceptance are important factors in realizing CRISPR's potential benefits to global food security.

The Exploitation of Orphan Legumes for Food, Income, and Nutrition Security in Sub-Saharan Africa

“…Gene editing entails the use of engineered nucleases to instigate cellular DNA repair pathways to make precise, site-directed alterations to an organism’s genome ( Bhowmik et al, 2021 ). Over the years, several genome editing techniques have been developed, including Zinc-finger nucleases (ZFNs), meganucleases, transcription activator-like effector nucleases (TALENs), clustered regularly interspaced short palindromic repeats (CRISPR)-CRISPR-associated protein 9 (Cas9) and homing endonucleases ( Gaj et al, 2016 ).…”

“…Over the years, several genome editing techniques have been developed, including Zinc-finger nucleases (ZFNs), meganucleases, transcription activator-like effector nucleases (TALENs), clustered regularly interspaced short palindromic repeats (CRISPR)-CRISPR-associated protein 9 (Cas9) and homing endonucleases ( Gaj et al, 2016 ). However, CRISPR/Cas9-mediated gene editing has emerged as the most straightforward, adaptable, and precise strategy for genetic manipulation in plants ( Bhowmik et al, 2021 ; Nadakuduti and Enciso-Rodríguez, 2021 ). The mechanism of action that underpins the CRISPR technology has been extensively reviewed elsewhere ( Gaj et al, 2016 ; Li et al, 2020 ; Wada et al, 2020 ; Bhowmik et al, 2021 ).…”

“…However, CRISPR/Cas9-mediated gene editing has emerged as the most straightforward, adaptable, and precise strategy for genetic manipulation in plants ( Bhowmik et al, 2021 ; Nadakuduti and Enciso-Rodríguez, 2021 ). The mechanism of action that underpins the CRISPR technology has been extensively reviewed elsewhere ( Gaj et al, 2016 ; Li et al, 2020 ; Wada et al, 2020 ; Bhowmik et al, 2021 ).…”

Genomics Associated Interventions for Heat Stress Tolerance in Cool Season Adapted Grain Legumes

“…However, in chickpeas, CRISPR/Cas9 editing was used for the 4-coumarate ligase ( 4CL ) and Reveille 7 ( RVE7 ) genes, which were associated with drought tolerance leading to targeted mutagenesis [ 265 ]. In addition to this, CRISPR/Cas9-based genome editing has also used for a number of genes in other legume crops including model legume species [ 266 ].…”

Conventional and Molecular Breeding Tools for Accelerating Genetic Gain in Faba Bean (Vicia Faba L.)

“…No CRISPR/Cas9 system has been reported for faba bean yet. The absence of an annotated reference genome for this crop poses challenges for the application of CRISPR/Cas gene editing, particularly with the design of specific gRNA-targeted genes of interest (Bhowmik et al, 2021). However, with recent gene discoveries for quality traits such as vicine-convicine (v-c) (Björnsdotter et al, 2021) and seed coat tannins (Gutierrez and Torres, 2019;Gutierrez et al, 2020), this technology may be used to advance our understanding of gene function and accelerate development of new cultivars with reduced anti-nutritional factors.…”