title: Shoot-specific down-regulation of protein farnesyltransferase (alpha-subunit) for yield protection against drought in canola.
abstract: Canola (Brassica napus L.) is one of the most important oilseed crops in the world and its seed yield and quality are significantly affected by drought stress. As an innate and adaptive response to water deficit, land plants avoid potential damage by rapid biosynthesis of the phytohormone abscisic acid (ABA), which triggers stomatal closure to reduce transpirational water loss. The ABA-mediated stomatal response is a dosage-dependent process; thus, one genetic engineering approach for achieving drought avoidance could be to sensitize the guard cell's responsiveness to this hormone. Recent genetic studies have pinpointed protein farnesyltransferase as a key negative regulator controlling ABA sensitivity in the guard cells. We have previously shown that down-regulation of the gene encoding Arabidopsis beta-subunit of farnesyltransferase (ERA1) enhances the plant's sensitivity to ABA and drought tolerance. Although the alpha-subunit of farnesyltransferase (AtFTA) is also implicated in ABA sensing, the effectiveness of using such a gene target for improving drought tolerance in a crop plant has not been validated. Here, we report the identification and characterization of the promoter of Arabidopsis hydroxypyruvate reductase (AtHPR1), which expresses specifically in the shoot and not in non-photosynthetic tissues such as root. The promoter region of AtHPR1 contains the core motif of the well characterized dehydration-responsive cis-acting element and we have confirmed that AtHPR1 expression is inducible by drought stress. Conditional and specific down-regulation of FTA in canola using the AtHPR1 promoter driving an RNAi construct resulted in yield protection against drought stress in the field. Using this molecular strategy, we have made significant progress in engineering drought tolerance in this important crop species.
authors.affiliation: Performance Plants, Inc., 700 Gardiners Road, Kingston, Ontario, Canada, K7M 3X9.
authors.forename: Yang
authors.initials: Y
authors.lastname: Wang
authors.forename: Michelle
authors.initials: M
authors.lastname: Beaith
authors.forename: Maryse
authors.initials: M
authors.lastname: Chalifoux
authors.forename: Jifeng
authors.initials: J
authors.lastname: Ying
authors.forename: Tina
authors.initials: T
authors.lastname: Uchacz
authors.forename: Carlene
authors.initials: C
authors.lastname: Sarvas
authors.forename: Rebecca
authors.initials: R
authors.lastname: Griffiths
authors.forename: Monika
authors.initials: M
authors.lastname: Kuzma
authors.forename: Jiangxin
authors.initials: J
authors.lastname: Wan
authors.forename: Yafan
authors.initials: Y
authors.lastname: Huang
mesh_terms: D000222:Adaptation, Physiological; D019883:Alkyl and Aryl Transferases / Q000378:metabolism*; D001483:Base Sequence; D029688:Brassica napus / Q000201:enzymology* / Q000235:genetics / Q000502:physiology; D003001:Cloning, Molecular; D018744:DNA, Plant; D015536:Down-Regulation; D055864:Droughts; D050537:Hydroxypyruvate Reductase / Q000235:genetics; D008969:Molecular Sequence Data; D018520:Plant Shoots
chemical_list: D018744:DNA, Plant; D050537:Hydroxypyruvate Reductase; D019883:Alkyl and Aryl Transferases; C064911:p21(ras) farnesyl-protein transferase