Microscopy of some interactions between Emphasis

Authors: N T Amponsah E E Jones H J Ridgway M V Jaspers

Publish Date: 2012/08/05

Volume: 41, Issue: 6, Pages: 665-673

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Abstract

This study investigated the endophytic interactions between Botryosphaeriaceae pathogens and their woody hosts and the role of wounds in development of infection of green tissues At 2 and 3 months after inoculating trunks of 2 year old grapevine plants with Neofusiciccum australe N luteum N parvum or Diplodia mutila sap samples provided no evidence of pathogen propagules indicating that the dieback symptoms observed at a distance from the lesions on inoculated sections of the trunks were not due to internally transmitted propagules However longitudinal sections cut from beyond trunk lesions showed hyphae of the four fungi grew within xylem vessels which was consistent with endophytic fungal development observed in previous experiments When conidia of N luteum were inoculated onto green shoots and leaves of potted grapevines which were wounded or nonwounded and excised or attached to living plants scanning electron microscope studies showed that conidial development was significantly affected by the condition of tissues On detached and wounded leaf and shoot surfaces most conidia had germinated by 3 h after inoculation and by 24 h had developed into networks of mycelium On attached and wounded leaf and shoot surfaces it took 24 h for most conidia to germinate However when green tissues were attached and nonwounded conidia did not adhere or germinate all conidia being shed from the tissues within 24 h These studies have provided explanations for phenomena observed during infection studies and have demonstrated that the pathogenhost interactions are complex warranting further examination of the physiology of the interactionsWe are grateful to New Zealand Winegrowers and Lincoln University for funding this research to Neil Andrews for his shilled help with viewing the specimens with scanning electron microscopy and to Brent Richards of the Lincoln University for maintaining the grapevine plants during the course of the experiments

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