Peach ( Prunus persica ) TAC1 protein interaction with a LIGHT HARVESTING CHLOROPHYLL A/B BINDING (LHCB) homolog and transcriptomic analyses reveal connections to photosynthesis.

Abstract

Plants receive and interpret external light, gravity, and temperature cues to both set and change the angles of their lateral organs for optimal growth and development. In recent years, the roles of the IGT/LAZY protein family in integrating light and gravity cues have become increasingly apparent. Here we investigated protein-protein interactions for peach ( Prunus persica ) TAC1 (PpeTAC1). TAC1 is a light-regulated IGT/LAZY family member involved in maintaining outward growth of lateral branches in numerous plant species. Using a yeast-two-hybrid screen with a peach library, we identified three candidate protein interactors, including a LIGHT HARVESTING CHLOROPHYLL A/B BINDING (LHCB) family protein. We found that neither TAC1 silencing nor PpeTAC1 overexpression in plum ( P. domestica ) altered chlorophyll content, despite a recent finding that LAZY1 -silenced plum trees have chlorotic leaves due to reduced chlorophyll. However, we identified multiple differentially expressed chloroplast-, photosynthesis-, and light-related genes between tac1 mutant and standard peaches. Collectively, we identified connections between PpeTAC1 and chloroplasts, photosynthesis-related machinery, and light. This data supports a role for the TAC1 protein as an integrator of light perception into mechanisms controlling lateral organ orientation in concert with or in parallel to the LAZY/DRO gravitropic-response pathway.