The BIG protein distinguishes the process of CO₂‐induced stomatal closure from the inhibition of stomatal opening by CO₂

Abstract

Summary We conducted an infrared thermal imaging‐based genetic screen to identify Arabidopsis mutants displaying aberrant stomatal behavior in response to elevated concentrations of CO 2.This approach resulted in the isolation of a novel allele of the Arabidopsis BIG locus (At3g02260) that we have called CO 2 insensitive 1 (cis1). BIG mutants are compromised in elevated CO 2‐induced stomatal closure and bicarbonate activation of S‐type anion channel currents. In contrast with the wild‐type, they fail to exhibit reductions in stomatal density and index when grown in elevated CO 2. However, like the wild‐type, BIG mutants display inhibition of stomatal opening when exposed to elevated CO 2. BIG mutants also display wild‐type stomatal aperture responses to the closure‐inducing stimulus abscisic acid (ABA).Our results indicate that BIG is a signaling component involved in the elevated CO 2‐mediated control of stomatal development. In the control of stomatal aperture by CO 2, BIG is only required in elevated CO 2‐induced closure and not in the inhibition of stomatal opening by this environmental signal. These data show that, at the molecular level, the CO 2‐mediated inhibition of opening and promotion of stomatal closure signaling pathways are separable and BIG represents a distinguishing element in these two CO 2‐mediated responses.

BIG regulates stomatal immunity and jasmonate production in Arabidopsis

“…The BIG gene encodes a calossin‐like protein required for auxin transport (Ruegger et al ., ; Gil et al ., ; Yamaguchi et al ., ). Recently, we reported that BIG is also involved in elevated CO 2 ‐induced stomatal closure (He et al ., ). In addition to regulating the uptake of CO 2 from the atmosphere and the loss of water vapor from the plant, stomata are also a major point of entry for many microbial pathogens entering plants.…”

“…BIG was re‐annotated based on the sequences of an overlapping set of RT‐PCR products. The gene encodes a predicted 5077 amino acid protein which is required for stomatal response to elevated concentration of CO 2 (He et al ., ). Mutations in BIG restrict overall plant growth and development, leading to plant architecture reshaping and delayed flowering (Ruegger et al ., ; Gil et al ., ; Yamaguchi et al ., ; Guo et al ., ).…”

New insights into the cellular mechanisms of plant growth at elevated atmospheric carbon dioxide concentrations

“…Jasmonic acid is known to play a significant role in mediating stomatal closure at e[CO 2 ] (Geng et al, ). A very recent study by He et al () revealed that a novel allele of the Arabidopsis BIG locus named cis1 is involved as a signalling component responsible for controlling stomatal aperture at e[CO 2 ]. Further, they indicated that loss of BIG function compromises activation of guard cell S‐type anion channels by bicarbonate at e[CO 2 ].…”

Chloroplastic Os3BGlu6 contributes significantly to cellular ABA pools and impacts drought tolerance and photosynthesis in rice

“…In seeds, ABA is involved in embryo development, desiccation tolerance, dormancy and germination (Wang et al , ). Additionally, ABA is involved in regulating the stomatal opening, a process crucial for controlling CO 2 concentrations for photosynthesis and water release for transpiration (Kim et al , ; He et al , ). ABA also limits the initiation of stomatal development and induces enlargement of pavement cells in Arabidopsis cotyledons (Tanaka et al , ).…”