Informations et ressources scientifiques
sur le développement des zones arides et semi-arides

Accueil du site → Doctorat → Australie → 1990 → Interactions between peanuts and fungi of the Aspergillus section flavi

Australian National University (1990)

Interactions between peanuts and fungi of the Aspergillus section flavi

Moody, Susan Frances

Titre : Interactions between peanuts and fungi of the Aspergillus section flavi

Auteur : Moody, Susan Frances

Université de soutenance : Australian National University

Grade : Doctor of Philosophy (PhD) 1990

Résumé partiel
Aspergillusflavus and A. parasiticus are responsible for contaminating peanuts with carcinogenic aflatoxins. Preharvest infection by A.flavus and A. parasiticus was examined in two peanut genotypes J II and PI 337394F, which exhibit enhanced levels of seed resistance to these fungi, and two genotypes TMV 2 and EC 76446(292), which are susceptible. Host resistance barriers to infection were identified among these genotypes. A.flavus and A. parasiticus were found to infect both resistant and susceptible peanut genotypes at all stages of fruit development. These fungi infected both resistant and susceptible genotypes to the same extent during flowering, aerial peg extension, immature poq and overmature pod development. The mature pods of resistant genotypes that had been drought-stressed for 30 days had significantly lower levels of infection levels than the susceptible genotypes. The region of the peanut peg at the interface of the air and soil was identified in both resistant and susceptible genotypes as a favoured site of infection. Susceptibility of pegs to infection by these fungi appears to have been enhanced by damage of the epidermis, caused by soil abrasion and dehydration. Growth of these fungi in the peg tissue was observed using light microscopy and found to be limited to the outer cell layers of the cortex and the epidermis. In mature fruit, fungal growth was observed (by plating on selective media and by microscopy) to extend from infected peg tissue into the pod pericarp. Among pods initially infected at the peg, the fungus rarely grew to the pod beak : _In intact, mature and over mature pods, A.flavus and A. parasiticus were rarely found to pass through the inner pericarp layers and invade the seeds. These inner pericarp layers were identified as vital components of resistance to seed invasion by these fungi.

Présentation

Version intégrale (294 Mb)

Page publiée le 24 janvier 2021