Spike-Stalk Injection Method Causes Extensive Phenotypic and Genotypic Variations for Rice Germplasm

Area of Science:

• Plant genetics and genomics
• Crop improvement and germplasm innovation
• Evolutionary biology and speciation

Background:

• Genetic diversity is crucial for crop improvement, with interspecific gene transfer offering valuable resources.
• The Spike-Stalk Injection (SSI) method facilitates direct genetic material introduction from non-mating species into crops.
• Inheritance patterns and mechanisms of SSI-induced variants remain poorly understood.

Purpose of the Study:

• To investigate the inheritance patterns and underlying mechanisms of rice variants generated by the SSI method.
• To identify genetic regions associated with improved yield-related traits in an SSI-modified rice line.
• To enhance understanding of plant genome evolution and domestication processes.

Main Methods:

• Screening of a rice variant (ERV1) with enhanced yield traits after introducing genomic DNA from *Oryza eichingeri* into *Oryza sativa L.* (RH78) via SSI.
• Genome-wide comparison to assess genomic heterozygosity differences between the variant and the recipient parent.
• Restriction-site associated DNA sequencing (RAD-seq) and association analysis in an F2 population to identify quantitative trait loci (QTLs).

Main Results:

• The ERV1 variant exhibited approximately 8-fold higher genomic heterozygosity compared to RH78.
• Five QTL regions associated with yield-related traits were identified in the ERV1 inbred F2 population.
• ERV1 inbred lines showed significantly lower genomic heterozygosity but a higher spontaneous mutation rate than the ERV1 parent.

Conclusions:

• The study provides preliminary insights into the inheritance patterns of SSI-induced rice variants.
• Identified QTL regions offer potential targets for further genetic improvement and understanding trait variation.
• Findings contribute novel perspectives on SSI mechanisms, plant genome evolution, domestication, and speciation.