Transcriptome-wide effect of Salix SmSPR1 in etiolated seedling of Arabidopsis

Microtubules and their regulatory proteins are involved in the regulation of plant cell morphology. SPIRAL1 (SPR1), a plant-specific microtubule-binding protein, is critical in regulating the anisotropic growth of plant cells. Our previous study showed that overexpressed Salix SmSPR1 genes in Arabidopsis thaliana caused right-handed spiral elongation in etiolated seedlings, but there were no morphological differences between wild-type and transgenic seedlings under varied light conditions. We then studied the transcriptional regulation patterns in transgenic plants engineered with the SmSPR1 gene. Transcriptomic results showed that a large number of differentially expressed genes were involved in plant light signal reception, chlorophyll synthesis and photosystem structure. Eleven gene families with 42 photosynthesis-related genes and 6 light-responsive genes were involved in regulation of cell morphology. Our results showed that these genes in the SmSPR1-ox line were particularly down-regulated under dark conditions. In addition, 33 TFs showed differences between SmSPR1-ox and wild-type lines. Taken together, the transcriptome analysis provides new insight into investigating the molecular mechanisms of light-induced cell morphological changes mediated by the microtubule binding protein SPR1.