Enhanced Rice Yellow Mottle Virus Resistance via CRISPR/Cas9-Targeted Mutagenesis of the Rice eIF(iso)4G Gene.

Area of Science:

• Plant Science
• Genetics
• Agricultural Biotechnology

Background:

• Rice yellow mottle disease (RYMD), caused by the rice yellow mottle virus (RYMV), is a major threat to rice production in sub-Saharan Africa.
• Developing RYMV-resistant rice genotypes is crucial for disease management, with genetic approaches like targeting susceptibility genes showing promise.
• Most rice varieties in Kenya are susceptible to RYMV, necessitating innovative resistance strategies.

Purpose of the Study:

• To enhance resistance to RYMV in Indica rice using CRISPR-Cas9 genome editing.
• To investigate the role of the eIF(iso)4G susceptibility gene in RYMV resistance.
• To assess the agronomic performance of edited rice lines.

Main Methods:

• CRISPR-Cas9 genome editing was employed to target the eIF(iso)4G gene in rice.
• A Cas9-OseIF(iso)4G-gRNA-expressing vector was introduced into rice calli via Agrobacterium-mediated transformation.
• Homozygous T2 mutant lines were evaluated for their response to RYMV infection and agronomic characteristics.

Main Results:

• CRISPR/Cas9-mediated knockout of the eIF(iso)4G gene conferred enhanced, partial resistance to RYMV in rice.
• RYMV infection was significantly reduced in the edited rice lines compared to wild-type.
• No significant differences in agronomic traits were observed between the mutant lines and wild-type plants.

Conclusions:

• CRISPR/Cas9-mediated gene knockout of eIF(iso)4G is an effective strategy for enhancing RYMV resistance in rice.
• This approach offers a valuable tool for breeding programs aiming to develop RYMV-resistant rice varieties.
• Further exploration of precise editing strategies like prime editing could lead to superior resistance alleles.