COBL7 is required for stomatal formation via regulation of cellulose deposition in Arabidopsis

Abstract

Summary As a key regulator of plant photosynthesis, water use efficiency and immunity, stomata are specialized cellular structures that adopt defined shapes. However, our knowledge about the genetic players of stomatal pore formation and stomatal morphogenesis remains limited. Forward genetic screening, positional cloning, confocal and electron microscopy, physiological and pharmacological assays were employed for isolation and characterization of mutants and genes. We identified a mutant, dsm1, with impaired cytokinesis and deformed stomata. DSM1 is highly expressed in guard mother cells and guard cells, and encodes COBRA‐LIKE 7 (COBL7), a plant‐specific glycosylphosphatidylinositol (GPI)‐anchored protein. COBRA‐LIKE 7 and its closest homologue, COBL8, are first enriched on the forming cell plates during cytokinesis, and then their subcellular distribution and abundance change are correlated with the progressive stages of stomatal pore formation. Both COBL7 and COBL8 possess an ability to bind cellulose. Perturbing the expression of COBL7 and COBL8 leads to a decrease in cellulose content and inhibition of stomatal pore development. Moreover, we found that COBL7, COBL8 and CSLD5 have synergistic effects on stomatal development and plant growth. Our findings reveal that COBL7 plays a predominant and functionally redundant role with COBL8 in stomatal formation through regulating cellulose deposition and ventral wall modification in Arabidopsis.

Genome-Wide Identification and Hormone Response Analysis of the COBL Gene Family in Barley

“…The dynamic reorganization of cellulose microfibrils within these guard cells occurs during stomatal movement, and the levels of cellulose and xyloglucan have a direct impact on the kinetic properties of guard cells [23]. The A. thaliana COBL7 protein and COBL8 protein jointly participate in the processes of cell division and stomatal development, influencing the formation of stomatal pores and the morphological development of stomata through the regulation of cellulose deposition and cell wall modification [24]. Cellulose plays a pivotal role in plants' responses to gravity, while brassinolide regulates the content of cellulose and mannan in response to gravity, serving as one of the key mechanisms underlying plants' gravitational responsiveness [25].…”