VIEW ARTICLE

Hydroxyphaseollin Production by Various Soybean Tissues: a Warning Against Use of “Unnatural” Host-Parasite Systems. N. T. Keen, Assistant Professor, National Science Foundation Student Science Training Program, Department of Plant Pathology, University of California, Riverside 92502; Robert Horsch, Student, National Science Foundation Student Science Training Program, Department of Plant Pathology, University of California, Riverside 92502. Phytopathology 62:439-442. Accepted for publication 5 November 1971. DOI: 10.1094/Phyto-62-439.

Confirming previous reports, rates of production of the antifungal pterocarpan 6a-hydroxyphaseollin (HP) were greater in inoculated hypocotyls of Harosoy 63 soybeans (monogenically resistant to Phytophthora megasperma var. sojae) than in the near-isogenic susceptible cultivar Harosoy. Hydroxyphaseollin was also produced by soybean roots, cotyledons, pods, and tissue culture callus when inoculated with P. megasperma var. sojae, but rates of production by these tissues were similar in the two cultivars. The data further implicated HP with the Phytophthora resistance of Harosoy 63 soybeans, since accelerated production in this cultivar relative to Harosoy was only observed in hypocotyls, the organ in which resistance is expressed naturally. Our data therefore warn against the use of “unnatural” plant tissues such as pods and tissue culture callus in investigations concerned with the elucidation of naturally occurring disease resistance mechanisms in plants.