AmiRNAi silencing of FaCRY2 delayed the growth of cultivated strawberry

As a plant blue light receptor, CRY2 plays pleotropic roles in regulating photomorphogenesis, flowering time and stress response. However, the function of CRY2 in the octoploid cultivated strawberry (Fragaria x ananassa Duch.) has not been identified. In this study, certain variation and functional divergences of the FaCRY2 protein were found in compared with its homologs in diploid model plants (AtCRY2 and SlCRY2). Quantitative RT-PCR analysis of the FaCRY2 showed the highest expression level in the leaf and flower tissues. The subcellular localization results indicate that the FaCRY2 was a nucleus-localized protein. The cry2 mutants, silenced by artificial micro-interfering RNA interference (AmiRNAi) using 'Benihoppe' strawberry as genetic background, showed a growth retardation, including dwarf phenotype, decreased free IAA content, delayed flowering time, deepened the lignification degree of petiole cells, decreased stomatal conductance and transpiration rate. RNA-seq analysis showed that there were 910 significantly differentially expressed genes (DEGs) between wild-type (WT) and cry2. They were mainly enriched in hormone regulation, cell development and stress response, etc. The decrease of IAA accumulation could be the main factor responsible for the delayed growth of cry2. Taken together, our results suggested the complex roles of FaCRY2 in the plant growth regulation in cultivated strawberry.