Lateral roots of carrot have a low impact on alloinfections in cavity spot epidemic caused by <Emphasis Type="Italic">Pythium violae</Emphasis> |
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Authors: | F Suffert |
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Institution: | (1) INRA, UMR1099 BiO3P (Biologie des Organismes et des Populations appliquée à la Protection des Plantes), 35653 Le Rheu, France;(2) Agrocampus Rennes, UMR1099 BiO3P, 35653 Le Rheu, France;(3) INRA, UMR1290 BIOGER-CPP (Biologie et Gestion des Risques en Agriculture-Champignons Pathogènes des Plantes), 78850 Thiverval-Grignon, France;(4) AgroParisTech, UMR1290 BIOGER-CPP, 78850 Thiverval-Grignon, France |
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Abstract: | Carrot cavity spot, caused by a complex of Pythium species, is characterized by sunken elliptical lesions on the taproot. Recent epidemiological studies of P. violae have demonstrated the occurrence of both primary and secondary infections, with two types of secondary infection, autoinfection
and alloinfection. Investigating the mechanisms underlying alloinfection and the role of carrot lateral roots, we asked whether
direct physical root contact plays a role in alloinfection and whether root exudates enhance mycelial growth in soil alone.
A rhizobox system was designed to differentiate the effects of each mechanism: a buffer zone created by nylon mesh was used
to test the first mechanism, and young carrots with a root system similar to lateral roots were used to test the second. Alloinfections
were generated in rhizoboxes via diseased taproots transplanted close to healthy, mature carrots. The nylon mesh had no significant
effect on disease intensity (reflecting alloinfection), providing evidence that mycelial growth in soil contributed more to
disease spread than did physical contact among roots. Nor did young carrots significantly affect alloinfection; thus root
exudates had little effect on mycelial growth. |
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Keywords: | Alloinfections Carrot cavity spot Pythium violae Rhizobox system Root-to-root contamination Soilborne pathogen |
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