title: Transgenic Arabidopsis thaliana plants expressing a β-1,3-glucanase from sweet sorghum (Sorghum bicolor L.) show reduced callose deposition and increased tolerance to aluminium toxicity.
abstract: Seventy-one cultivars of sweet sorghum (Sorghum bicolor L.) were screened for aluminium (Al) tolerance by measuring relative root growth (RRG). Two contrasting cultivars, ROMA (Al tolerant) and POTCHETSTRM (Al sensitive), were selected to study shorter term responses to Al stress. POTCHETSTRM had higher callose synthase activity, lower β-1,3-glucanase activity and more callose deposition in the root apices during Al treatment compared with ROMA. We monitored the expression of 12 genes involved in callose synthesis and degradation and found that one of these, SbGlu1 (Sb03g045630.1), which encodes a β-1,3-glucanase enzyme, best explained the contrasting deposition of callose in ROMA and POTCHETSTRM during Al treatment. Full-length cDNAs of SbGlu1 was prepared from ROMA and POTCHETSTRM and expressed in Arabidopsis thaliana using the constitutive cauliflower mosaic virus (CaMV) 35S promoter. Independent transgenic lines displayed significantly greater Al tolerance than wild-type plants and vector-only controls. This phenotype was associated with greater total β-1,3-glucanase activity, less Al accumulation and reduced callose deposition in the roots. These results suggest that callose production is not just an early indicator of Al stress in plants but likely to be part of the toxicity pathway that leads to the inhibition of root growth.
authors.affiliation: Laboratory of Soil and Plant Molecular Genetics, College of Plant Science, Jilin University, Changchun, 130062, China; Engineering Research Center for Biomass Resource Utilization of Jilin Province, Changchun, 130062, China.
authors.forename: Hui
authors.initials: H
authors.lastname: Zhang
authors.forename: Wu Liang
authors.initials: WL
authors.lastname: Shi
authors.forename: Jiang Feng
authors.initials: JF
authors.lastname: You
authors.forename: Ming Di
authors.initials: MD
authors.lastname: Bian
authors.forename: Xiao Mei
authors.initials: XM
authors.lastname: Qin
authors.forename: Hui
authors.initials: H
authors.lastname: Yu
authors.forename: Qing
authors.initials: Q
authors.lastname: Liu
authors.forename: Peter R
authors.initials: PR
authors.lastname: Ryan
authors.forename: Zhen Ming
authors.initials: ZM
authors.lastname: Yang
mesh_terms: D000535:Aluminum / Q000032:analysis / Q000633:toxicity*; D017360:Arabidopsis / Q000187:drug effects / Q000201:enzymology / Q000378:metabolism* / Q000502:physiology; D043326:Glucan 1,3-beta-Glucosidase / Q000378:metabolism* / Q000502:physiology; D005936:Glucans / Q000032:analysis / Q000378:metabolism* / Q000502:physiology; D018517:Plant Roots / Q000737:chemistry / Q000502:physiology; D030821:Plants, Genetically Modified / Q000187:drug effects / Q000201:enzymology / Q000378:metabolism* / Q000502:physiology; D060888:Real-Time Polymerase Chain Reaction; D045868:Sorghum / Q000187:drug effects / Q000201:enzymology / Q000378:metabolism* / Q000502:physiology
chemical_list: D005936:Glucans; C048306:callose; D000535:Aluminum; D043326:Glucan 1,3-beta-Glucosidase
keywords: Arabidopsis; β-1,3-glucanase gene