Toxicants, genetic control susceptibility

Genetic control of susceptibility to toxicants operates through a variety of mechanisms. One of these is metabolic. In animals, the murine Ah complex represents a "cluster" of genes exercising temporal control on tissue-specific regulatory genes... 

Because 2-tridecanone-mediated resistance to sexta and L. decemlineata is genetically distinct from the lamellar-based resistance to zea, it would be possible to develop tomato cultivate resistant to sexta and decemlineata but susceptible to zea. On such cultivate, the 2-tridecanone-mediated induction of elevated tolerance to some insecticides might make control of zea more difficult (55, 58). The severity of H. zea as a pest problem on such cultivate would be further exacerbated if 2-tridecanone associated with the resistant foliage seriously interfered with insect parasitoids and predators important in suppressing natural populations of zea. Because of its occurrence in the foliar glandular trichomes, and because of its broad spectrum toxicity to insects, we considered it likely that parasitoids and predaceous insects searching the resistant foliage for prey would be exposed to potentially toxic levels of 2-tridecanone. 

The pathotype responsible for tomato stem canker produces 3 related toxins (Fig. 3). Aspartate and certain products of aspartate metabolism (e.g. orotic acid) protect tomato plants against the toxins, and it is thought that toxicity may be due to inhibition of aspartate transcarbamylase. Susceptibility to the disease is controlled by a single genetic locus with 2 alleles. 

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