Suppressing a mitochondrial calcium uniporter activates the calcium signaling pathway and promotes cell elongation in cotton

Abstract

Mitochondrial calcium uniporter (MCU) is a conserved calcium ion (Ca) transporter in the mitochondrial inner membrane of eukaryotic cells. How MCU proteins regulate Ca flow and modulate plant cell development remain largely unclear. Here, we identified the gene encoding a MCU protein that negatively regulates plant development and fiber elongation in cotton (). expressed constitutively in various tissues with the higher transcripts in elongating fiber cells. Knockdown of in cotton significantly elevated the plant height and root length. The calcium signaling pathway was significantly activated and calcium sensor genes, including Ca dependent modulator of interactor of constitutively active ROP () calmodulin like protein (, calcium-dependent protein kinases (), calcineurin B-like protein (), and CBL-interacting protein kinases (), were dramatically upregulated in silenced plants. Metabolic processes were preferentially enriched, and genes related to regulation of transcription were upregulated in silenced plants. The contents of Ca and HO were significantly increased in roots and leaves of silenced plants. Fiber length and Ca and HO contents in fibers were significantly increased in silenced plants. This study indicated that plays a negative role in regulating cell elongation in cotton, thus expanding understanding in the role of MCU proteins in plant growth and development.