Distribution and Variation of Indole Glucosinolates in Woad (Isatis tinctoria L.)

Abstract

The exceptionally high levels in woad (Isatis tinctoria L.) of three indolic goitrogens, namely glucobrassicin, neoglucobrassicin, and glucobrassicin-l-sulfonate, permit the facile study of their distribution in the plant and their changes during its development. Woad seeds contain as much as 0.23 % fresh weight of glucobrassicin but no other indole glucosinolate, while 1-week-old seedlings also contain substantial amounts of neoglucobrassicin and glucobrassicin-l-sulfonate in their shoots whether grown in the light or dark. The sulfonate is not found in roots, and light depresses neoglucobrassicin levels in shoots. Sterile root cultures synthesize glucobrassicin and neoglucobrassicin, and significant quantities of these were even found to be excreted by the roots of intact sterile seedlings in culture. This may explain the long known deleterious effect of woad and other cruciferous crops on subsequent plantings and the observation could be of ecological importance. Long term changes in levels of all three substances in the plant are similar and are compatible with earlier suggestions that the compounds could be auxin precursors at the time of flower stem elongation. Since sterile seedlings readily incorporate 3SO42-into indole glucosinolates and relative specific radioactivities suggest that glucobrassicin is the precursor of the other two compounds, pathways of goitrogen biosynthesis should be relatively easily determined in this material.In previous papers (9, 10) of the plant (e.g., during very rapid growth such as "bolting" of the flower shoot).Animal nutrition is influenced by indole glucosinolates due to the fact that the enzyme myrosinase (which is released from special cells in the plant tissues upon crushing) acts to release the goitrogenic thiocyanate ion from them (10, 41). In areas where large quantities of brassicaceous crops are eaten or fed to cows (which transfer part of the thiocyanate to their milk) these thiocyanate ions are at least partially responsible for endemic goiter in the human population (Ref. 28 and references therein).Finally, the distribution of indole glucosinolates in the plant kingdom has provided useful information for chemotaxonomic considerations (1 1. 31, 33).As the woad plant has exceptionally high levels of three indole glucosinolates, its study should cast light on these topics. We have examined the changes which occur in the levels of each of the indole glucosinolates in the shoots and roots of woad plants during germination, growth, and flowering. A similar study with the mustard plant (Sinapis alba L.) has recently been published by Bergmann (3). MATERIALS AND METHODSPlant Material. Seeds of woad (l. tinctoria L.) were collected from plants which had flowered in Yale University's Marsh Botanic Garden in 1967 and had been stored at room temperature over the winter. The field-grown woad plants were obtained from the crop produced by sowing these seeds in the spring of 1968.For sterile culture, seeds were dissected out of the fruits, sterilized as described pr...

Occurrence and formation of indole-3-acetamide in Arabidopsis thaliana

“…Seed glucosinolates are rapidly metabolized during the onset of germination (Elliot and Stowe 1971;Bodnaryk and Palaniswamy 1990) including glucobrassicin, a major seed glucosinolate in A. thaliana (Petersen et al 2002). iv.…”

Molecular characterization of two cloned nitrilases from Arabidopsis thaliana: key enzymes in biosynthesis of the plant hormone indole-3-acetic acid.

“…The homologous, soluble enzyme was also the one studied earlier (28,29), and it may be the one responsible for the basic auxin supply of the growing plant. Nitrilase II parallels the abundance and distribution of glucosinolates in A. thaliana and other Brassicaceae (11,(36)(37)(38)(39), suggesting functional connections. The enzyme could be involved in furnishing auxin from glucosinolates during the early stages of seed germination and seedling growth (36).…”

“…Nitrilase II parallels the abundance and distribution of glucosinolates in A. thaliana and other Brassicaceae (11,(36)(37)(38)(39), suggesting functional connections. The enzyme could be involved in furnishing auxin from glucosinolates during the early stages of seed germination and seedling growth (36).…”

Distribution of glucosinolates and sulphur‐rich cells in roots of field‐grown canola (Brassica napus)

“…They showed that within the rhizosphere concentrations of 2‐PE ITC are sufficient to ‘select’ an active microbial population different from that of the bulk soil. This work has revived earlier studies which reported release of ITCs (Choesin & Boerner, 1991; Schreiner & Koide, 1993) or GSLs (Elliott & Stowe, 1971) from healthy, undamaged roots. Together, these findings raise questions of where GSLs are located in root systems, where and how their hydrolysis liberates ITCs into the rhizosphere of living roots, and what the links are to normal root developmental processes.…”