Abstract
Incipient and advanced tumors were present in the hypocotyl and the 1st 3 internodes of severely stunted, 10-node plants of G. hirsutum .times. G. gossypioides hybrid. Tumors, free of bacteria or fungi, were initiated at or near the vascular cambium as small clumps of hypertrophied parenchyma. Disorganization of segments of the vascular cambium occurred in association with tumor initiation. Subsequent growth of tumors caused disorganization of the phloem and formation of wedge-shaped masses of tumorous parenchyma in the xylem. Isolated tumors occurred in the pith of 14-node plants. The stem xylem of tumorous 10-node plants had increased levels of the flavanols catechin and gallocatechin, normally present only in a few scattered parenchyma cells in nontumorous xylem tissue. Several terpenoid aldehydes, predominantly hemigossypol and methoxyhemigossypol, occurred in tumorous xylem tissue, but were absent in nontumorous tissues. Histochemical reagents showed that the flavanols and terpenoid aldehydes were associated with incipient and advanced stages of tumors in the stem xylem.
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