Dataset Information

Selection for low dormancy in annual ryegrass (Lolium rigidum) seeds results in high constitutive expression of a glucose-responsive ?-amylase isoform.

ABSTRACT: BACKGROUND AND AIMS: ?-Amylase in grass caryopses (seeds) is usually expressed upon commencement of germination and is rarely seen in dry, mature seeds. A heat-stable ?-amylase activity was unexpectedly selected for expression in dry annual ryegrass (Lolium rigidum) seeds during targeted selection for low primary dormancy. The aim of this study was to characterize this constitutive activity biochemically and determine if its presence conferred insensitivity to the germination inhibitors abscisic acid and benzoxazolinone. METHODS: ?-Amylase activity in developing, mature and germinating seeds from the selected (low-dormancy) and a field-collected (dormant) population was characterized by native activity PAGE. The response of seed germination and ?-amylase activity to abscisic acid and benzoxazolinone was assessed. Using an alginate affinity matrix, ?-amylase was purified from dry and germinating seeds for analysis of its enzymatic properties. KEY RESULTS: The constitutive ?-amylase activity appeared late during seed development and was mainly localized in the aleurone; in germinating seeds, this activity was responsive to both glucose and gibberellin. It migrated differently on native PAGE compared with the major activities in germinating seeds of the dormant population, but the enzymatic properties of ?-amylase purified from the low-dormancy and dormant seeds were largely indistinguishable. Seed imbibition on benzoxazolinone had little effect on the low-dormancy seeds but greatly inhibited germination and ?-amylase activity in the dormant population. CONCLUSIONS: The constitutive ?-amylase activity in annual ryegrass seeds selected for low dormancy is electrophoretically different from that in germinating seeds and its presence confers insensitivity to benzoxazolinone. The concurrent selection of low dormancy and constitutive ?-amylase activity may help to enhance seedling establishment under competitive conditions.

SUBMITTER: Goggin DE

PROVIDER: S-EPMC3503496 | biostudies-literature | 2012 Dec

REPOSITORIES: biostudies-literature

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Selection for low dormancy in annual ryegrass (Lolium rigidum) seeds results in high constitutive expression of a glucose-responsive α-amylase isoform.

Goggin Danica E DE Powles Stephen B SB

Annals of botany 20120921 8

<h4>Background and aims</h4>α-Amylase in grass caryopses (seeds) is usually expressed upon commencement of germination and is rarely seen in dry, mature seeds. A heat-stable α-amylase activity was unexpectedly selected for expression in dry annual ryegrass (Lolium rigidum) seeds during targeted selection for low primary dormancy. The aim of this study was to characterize this constitutive activity biochemically and determine if its presence conferred insensitivity to the germination inhibitors a ...[more]

PMID: 23002268

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Project description:Rigid ryegrass (Lolium rigidum) is one of the most troublesome weeds in different crops in the Mediterranean region. A rigid ryegrass biotype from an olive grove in Jaén province (Andalusía, southern Spain), potentially resistant to glyphosate (RG), was tested for its resistance level through dose-response assays using a susceptible biotype (SG). To test the hypothesis of a non-target-site-based resistance, as point mutations are far less common mechanisms of glyphosate resistance, studies were also conducted to elucidate whether resistance was associated with biochemical, metabolism, molecular and/or physiological mechanisms. Alternative herbicide-based control options, including single-herbicide or herbicide mixtures with glyphosate, applied at seedling, tillering or full heading stages, were tested in field experiments for 2 years for their efficacy against rigid ryegrass plants and their effects on the soil seed bank. Resistance levels of the RG biotype were 23- (LD50) and 7-fold (GR50) higher compared to the SG biotype. The SG biotype exhibited a significantly greater shikimic acid accumulation than the RG one. At 96 HAT, 58 and 89% of applied 14C-glyphosate was up taken by leaves of RG and SG biotype plants, respectively, and, at this time, a significantly higher proportion of the glyphosate taken up by the treated leaf remained in its tissue in RG plants compared to the SG ones. The RG biotype did not reveal any point mutation in the glyphosate target site EPSP synthase. Overall, results confirmed reduced glyphosate uptake and translocation as being the mechanism involved in glyphosate resistance in the RG biotype. RG biotype responses to the alternative treatments tested in situ indicated that herbicide applications at the later growth stage tended to be less effective in terms of immediate effects on population size than earlier applications, and that only in some cases, the removal of at least 85% of the RG biotype was achieved. However, with few exceptions, the alternative treatments tested appeared to be highly effective in reducing the seed bank irrespective of the growth stage. The frequency of the resistant phenotype in the progeny of surviving plants of the RG biotype was dependent on treatment. Results suggest that a potential exists for effective management of glyphosate-resistant rigid ryegrass in olive groves in southern Spain.

Dataset Information

Selection for low dormancy in annual ryegrass (Lolium rigidum) seeds results in high constitutive expression of a glucose-responsive ?-amylase isoform.

Publications

Selection for low dormancy in annual ryegrass (Lolium rigidum) seeds results in high constitutive expression of a glucose-responsive α-amylase isoform.

Similar Datasets

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