This alternation of matching and non-matching ( or unlocking and re-locking ) is an essential feature of any system of locking, and it is possible only in a discontinuous pathosystem.
12.
The n / 2 model ( pronounced either en over two or'half en') suggests the mode of operation of the gene-for-gene relationship in a wild plant pathosystem.
13.
""'Pathosystem balance " "'means that the parasite does not endanger the survival of the host; and that the resistance in the host does not endanger the survival of the parasite.
14.
Conversely, in a continuous pathosystem just one matching allo-infection on each host individual is required for that individual to be parasitised for the rest of its life which, in the case of some evergreen trees, may endure for centuries.
15.
It can also be argued that the gene-for-gene relationship must function on a basis of heterogeneity in the wild pathosystem because the gross instability of the'boom and bust'of modern plant breeding would have no evolutionary survival value.
16.
Crops that are derived from a continuous wild pathosystem ( e . g ., aroids, banana, cassava, citrus, cocoa, coconut, date palm, ginger, mango, oil palm, olive, papaya, pineapple, pyrethrum, sisal, sugarcane, sweet potato, tea, turmeric, vanilla, yams ) have no gene-for-gene relationships, not withstanding a few erroneous reports to the contrary.
