The ERECTA gene regulates plant transpiration efficiency in Arabidopsis

Abstract

Assimilation of carbon by plants incurs water costs. In the many parts of the world where water is in short supply, plant transpiration efficiency, the ratio of carbon fixation to water loss, is critical to plant survival, crop yield and vegetation dynamics. When challenged by variations in their environment, plants often seem to coordinate photosynthesis and transpiration, but significant genetic variation in transpiration efficiency has been identified both between and within species. This has allowed plant breeders to develop effective selection programmes for the improved transpiration efficiency of crops, after it was demonstrated that carbon isotopic discrimination, Delta, of plant matter was a reliable and sensitive marker negatively related to variation in transpiration efficiency. However, little is known of the genetic controls of transpiration efficiency. Here we report the isolation of a gene that regulates transpiration efficiency, ERECTA. We show that ERECTA, a putative leucine-rich repeat receptor-like kinase (LRR-RLK) known for its effects on inflorescence development, is a major contributor to a locus for Delta on Arabidopsis chromosome 2. Mechanisms include, but are not limited to, effects on stomatal density, epidermal cell expansion, mesophyll cell proliferation and cell-cell contact.

Genetic Analysis of Water Use Efficiency in Rice (Oryza sativa L.) at the Leaf Level

“…The QTL with the largest effect on Δ 13 C explained more than 19% of the phenotypic variation. Although one study in Arabidopsis found a major QTL encoding the transcription factor, ERECTA, which explained up to 64% of the phenotypic variation in a Landsberg × Columbia RI population (Masle et al 2005), studies evaluating genetic variation for carbon isotope discrimination in other plant species have identified multiple QTLs of smaller effect associated with the trait. For example, in another population of Arabidopsis, two to five QTLs were identified Juenger et al 2005).…”

“…In the work on Arabidopsis by Masle et al (2005), the ERECTA gene underlying a Δ 13 C QTL was associated with both stomatal limitations on photosynthesis and leaf photosynthetic capacity at saturating CO 2 . In Arabidopsis, when two NILs were compared to the Landsberg erecta wild type, a significant difference in stomatal conductance (and transpiration efficiency) was associated with Δ 13 C QTLs .…”

“…The first QTLs associated with Δ 13 C were reported by Martin et al (1989) in tomato and since that time QTLs for Δ 13 C have been identified in rice (Price et al 2002) and several other plant species (Brendel et al 2002;Casasoli et al 2004;Diab et al 2004;Ellis et al 2002;Gleick 2003;Hausmann et al 2005;Masle et al 2005;Rebetzke et al 2008;Saranga et al 2004;Scalfi et al 2004;Specht et al 2001;Teulat et al 2002;Thumma et al 2001). Until now, all QTL studies conducted in rice involved segregating populations evaluated at different growth stages in field environments.…”

Phototropins But Not Cryptochromes Mediate the Blue Light-Specific Promotion of Stomatal Conductance, While Both Enhance Photosynthesis and Transpiration under Full Sunlight

“…The d values were then converted to carbon isotopic discrimination values (D). The D value was calculated according to Masle et al (2005) …”

“…Since these effects were observed close to midday, when irradiance levels were high, cry1 cry2 and phot1 phot2 could limit photosynthesis by lowering the flux of CO 2 . To investigate the long-term transpiration efficiency (CO 2 fixed/water loss ratio), the isotopic discrimination against 13 CO 2 with respect to 12 CO 2 (D; Farquhar and Richards, 1984;Masle et al, 2005) in plants grown under natural radiation was analyzed. The wild type and the cry1 cry2 and phot1 phot2 mutants presented similar D values (mean 6 SE in D per million, n = 3; the wild type, 22.1 6 0.1; cry1 cry2, 21.6 6 0.5; phot1 phot2, 21.8 6 0.4; P = 0.69), indicating that lower photosynthetic rates should accompany the lower transpiration rates presented by cry1 cry2 and phot1 phot2.…”