Histopathological assessment on the lotus rhizome tissue infected by Fusarium spp.causing lotus rhizome rot
Lotus is the most important aquatic vegetable in China and has the largest cultivation area.With the expansion of cultivation and the simplification of agricultural practices,various lotus diseases have been becom-ing more serious,among which lotus rhizome rot disease is the most harmful and the most difficult to control.At present,there are few research reports on the pathogenesis of Fusarium spp.causing lotus rhizome rot disease around the world.From the microscopic and ultra-microscopic levels,this study revealed the changes to the rhi-zome and its vascular tissues during Fusarium infection.The observation of paraffin-embedded tissue sections showed that with the development of the disease,necrotic cells stained by toluidine blue appeared around the vascular bundles,and the closer to the bundles,the more numerous necrotic cells and the more densely distribu-ted.In order to further reveal the influence of pathogen infection on vascular bundles,brightfield optical and scanning electron microscopy were used to observe the lotus fibers in the diseased lotus rhizomes.The results showed that the smooth and compact lotus fibers became rough and dispersed with the disease tending to be more severe,and a large number of galls-like protrusions and other possible metabolic attachments were attached to the surface.These changes to the vascular bundles are likely to reduce the water and nutrient transportation,and finally the aboveground parts of the plant exhibited the symptoms of water loss and wilting.The results of this study revealed the cellular biological mechanism of the disease symptom development,and provided a basis of histology for the breeding of resistant varieties in the future.
lotus rhizome rotFusarium spp.pathogenesishistologyscanning electron microscopylotus fiber
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