Meloidogne incognita (nematode) parasitism of Lycopersicon esculentum (tomato) plants : Ethylene action in susceptible and resistant host responses

Involvement of ethylene in the etiology of tomato plants (Lycopersicon esculentum) infected with the root-knot nematode (Meloidogyne incognita) was investigated. Endogenous root concentrations of ethylene were not significantly different in uninfected resistant var. Anahu and susceptible var. Vendor plants. Exposure of resistant plants to high doses of infectious nematode larvae did not affect root ethylene concentrations during the subsequent 30 day period. The possibility that ethylene may be involved in the mechanism of resistance is therefore not supported by these experiments. In no experiments did ethylene concentrations in roots of susceptible plants increase significantly subsequent to ~ incognita infestation. This result is not consistent with the hypothesis in the literature which suggests that increased ethylene production accompanies gall formation. Growth of susceptible tomato plants was affected by ~ incognita infestation such that root weights increased (due to galling), stem heights decreased and top weights increased. The possibility that alterations in stem growth resulted from increased production of 'stress' ethylene is discussed. Growth of resistant plants was unaffected by exposure to high doses of ~ incognita and galls were never detected on the roots of these plants. Root ethane concentrations generally varied in parallel with root ethylene concentrations although ethane concentrations were without exception greater. In 4 of 6 experiments conducted ethane/ethylene ratios increased significantly with time. These results are discussed in the light of published data on the relationship between ethane and ethylene synthesis. The term infested is used throughout this thesis in reference to plants whose root systems had been exposed to nematodes and does not distinguish between the susceptible and resistant response.

Ontario Tender Fruit Grower’s Marketing Board Fonds, 1960, 1967, 1969-1977, 1980-1981, 1987

The Ontario Tender Fruit Marketing Board operates under the Farm Producers Marketing Act. It covers all tender fruit farmers who produce either fresh or canned products. Today the board has over 500 grower-members. Tender fruit in the Niagara region includes: peaches, pears, plums, grapes and cherries. The fruits are used in a number of different ways, from jams and jellies to desserts, sauces and wine. Peaches were first harvested along the Niagara river in 1779. Peter Secord (Laura Secord’s uncle) is thought to be the first farmer to plant fruit trees when he took a land grant near Niagara in the mid 1780s. Since the beginnings of Secord’s farm, peaches, pears and plums have been grown in the Niagara region ever since. However, none of the original varities of peach trees remain today. Peaches were often used for more than eating by early settlers. The leaves and bark of the tree was used to make teas for conditions such as chronic bronchitis, coughs and gastritis. Cherries have been known to have anti-inflammatory and pain relieving properties. Like peaches and cherries, pears had many uses for the early pioneers. The wood was used to make furniture. The juice made excellent ciders and the leaves provided yellow dyes. Plums have been around for centuries, not only in the Niagara region, but throughout the world. They have appeared in pre-historic writings and were present for the first Thanksgiving in 1621. The grape industry in Ontario has also been around for centuries. It began in 1798 when land was granted to Major David Secord (brother-in-law to Laura Secord) slightly east of St. David’s, on what is Highway No. 8 today. Major Secord’s son James was given a part of the land in 1818 and in 1857 passed it onto Porter Adams. Adams is known to be the first person to plant grapes in Ontario1. Tender fruits are best grown in warm temperate climates. The Niagara fruit belt, stretching 65km from Hamilton to Niagara on the Lake, provides the climate necessary for this fruit production. This belt produces 90% of Ontario’s annual tender fruit crop. It is one of the largest fruit producing regions in all of Canada.

Starvation Induces Expression of the Plant-Adhesin Gene, Mad2, of the Entomopathogenic Fungus Metarhizium robertsii.

Metarhizium robertsii is an entomopathogenic fungus that is additionally plant rhizosphere competent. Two adhesin-encoding gens, Mad1 and Mad2, are involved in insect pathogenesis or plant root colonization, respectively. This study examined differential expression of the Mad genes for M robertsii grown on a variety of insectand plant-related substrates. Mad1 was up regulated in response to insect cuticles and up regulation of Mad2 resulted from root exudates, tomato stems and non-preferred carbohydrates. A time course analysis that compared water, minimal media, and nutrient rich broth revealed Mad2 gene expression increased as nutrient availability decreased. The regulation of Mad2 compared to known stress-related genes (Hsp30, Hsp70 and ssgA) under various stresses (nutrient, pH, osmotic, oxidative, temperature) revealed Mad2 to be generally up regulated by nutrient starvation only. Examination of the Mad2 promoter region revealed two copies of a stress-response element (S TRE) known to be regulated under the general stress response pathway.