Fusarium crown rot under continuous cropping of susceptible and partially resistant wheat in microcosms at elevated CO2. (30th January 2014)

• Record Type: Journal Article
• Authors: Khudhair, M.; Melloy, P.; Lorenz, D. J.; Obanor, F.; Aitken, E.; Datta, S.; Luck, J.; Fitzgerald, G.; Chakraborty, S.
• Is Part Of: Plant pathology. Volume 63:Number 5(2014:Oct.)
• Page Start: 1033
• Page End: 1043
• Publication Date: 2014-01-30
• Subjects: Agricultural pests -- Periodicals; Plant diseases -- Periodicals; 632
• DOI: 10.1111/ppa.12182
• Languages: English
• ISSNs: 0032-0862

Abstract

<abstract abstract-type="main" id="ppa12182-abs-0001"> <title> <x xml:space="preserve">Abstract</x> </title> <p>This study examines the CO<sub>2</sub>‐mediated influence of plant resistance on crown rot dynamics under continuous cropping of partially resistant wheat line 249 and the susceptible cultivar Tamaroi. Disease incidence, severity, deoxynivalenol and <italic>Fusarium</italic> biomass were assessed after each cycle in microcosms established at ambient and 700 mg kg<sup>−1</sup> CO<sub>2</sub> using soil and stubble of these wheat lines from a field experiment with free to air CO<sub>2</sub> enrichment. Monoconidial isolates from wheat stubble were collected initially, and after five cropping cycles, to compare the frequency and aggressiveness of <italic>Fusarium</italic> species in the two populations. Aggressiveness was measured using a high‐throughput seedling bioassay. At elevated CO<sub>2</sub>, the higher initial incidence in Tamaroi increased with cropping cycles, but incidence in 249 remained unchanged. Incidence at ambient CO<sub>2</sub> did not change for either line. Elevated CO<sub>2</sub> induced partial resistance in Tamaroi, but not in 249. Increased <italic>Fusarium</italic> biomass in wheat tissue at elevated CO<sub>2</sub> matched raised deoxynivalenol of the stem base in both lines. After five cycles of continuous wheat cropping, aggressiveness increased in pathogenic <italic>F. culmorum</italic> and <italic>F. pseudograminearum</italic> by 110%, but decreased in weakly pathogenic <italic>F. equiseti</italic> and <italic>F. oxysporum</italic> by 50%. CO<sub>2</sub> and host resistance interactively influenced species frequency, and the highly aggressive <italic>F. pseudograminearum</italic> became dominant on Tamaroi irrespective of CO<sub>2</sub> concentration, while its frequency declined on 249. This study shows that induced resistance at elevated CO<sub>2</sub> will not reduce crown rot severity, or impede the selection and enrichment of <italic>Fusarium</italic> populations with increased aggressiveness.</p> </abstract>