Help needed: disease identification

[at rsvs.ulaval.ca]

Unidentified Arabidopsis disease

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I seek help to identify and find a cure to a disease destroying some 
of our Arabidopsis plants. This disease attacks plants grown in soil 
in growth chambers. Up to now, attempts to identify this pathogen were 
inconclusive.

The first symptom detected is a senescence of the basal leaves. This 
senescence later spreads upward along all (or sometimes only one) of 
the stems. A premature wilting of higher stems and inflorences is also 
often observed, associated with a hook-like bending at a dried stem 
segment.

The disease is presumed to be spreading vascularly. It does not appear 
to be transmitted through seeds since a normal amount of disease is 
noted among individuals originating from seeds collected on affected 
plants. Furthermore, our seeds are routinely sterilized and germinated 
in vitro. It seems also unlikely to be related to a nutrient 
deficiency or an air-borne pathogen since it is often noted that only 
one or a few plants per container are affected, even when several 
plants touch each other. 

We have experienced in the past a few, sporadic, occurrences of this 
disease. The number of plants affected has, however, recently 
increased severely. I would be very grateful for insights from anyone 
facing a similar problem and/or having successfully identified and 
defeated this pathogen. Thank you for your attention.

Martine Jean
Université Laval
e-mail: mjean at biota.rsvs.ulaval.ca