Overexpression of chimeric GRF-GIF improves regeneration efficiency in diploid strawberry Hawaii 4

Plant breeding played a very important role in transforming strawberries from being a very niche crop with a small geographical footprint into an agroeconomically important crop grown across the planet. But even modern marker assisted breeding technique in strawberry takes a considerable amount of time over multiple generations to come up with a plant with desirable traits. To circumvent this problem the best solution is genetic engineering where a transgenic strawberry can be raised through tissue culture in a short span of time.Here we show that ectopic expression of GRF4-GIF1 chimera from multiple sources into strawberry allow faster regeneration of plants. We also report that unregulated expression of miRNA resistant version of VitisGRF4-GIF1 allowed faster regeneration but abnormal maturation of plantlets. On the other hand, TriticumGRF4-GIF1 resulted in abnormal leaflet formation in the mature strawberry plants.RNA sequencing analysis indicates the differentially higher expression of FvExpansin in the TriticumGRF4-GIF1 lines might be responsible for the leaf abnormality. Retransformation experiment on the GRF4-GIF1 overexpression lines indicates faster regeneration of healthy plants in case of VitisGRF4-GIF1 as compared to empty vector transformed plants. Thus, we could show that ectopic expression of GRF4-GIF1 is beneficial for faster regeneration, but source of the gene might also play a very important role for the outcome.