Occurrence of terpenoid aldehydes and lysigenous cavities in the 'glandless' seeds of Australian Gossypium species

The presence of lysigenous cavities filled with terpenoid aldehydes (generically termed 'gossypol') in most tissues of cultivated cottons and their relatives imparts natural resistance to a variety of insect, fungal, and bacterial pests. Deposition of terpenoid aldehydes in cultivated cotton seed, however, renders cottonseed oils and protein meals toxic to non-ruminant animals, including humans. Seeds of the so-called 'glandless-seeded' Australian Gossypium L. species (Gossypium subgenus Sturtia (R.Br.) Tod.) reportedly lack terpenoid aldehydes, and thus may represent an important genetic resource in the development of cottonseed oils and protein meals free of these toxins. Information supporting this assertion, however, is fragmentary and contradictory. To resolve this, seeds of all known Australian Gossypium species were surveyed chemically and anatomically. Immature lysigenous cavities were present in seeds of all 18 species. Lysigenous cavities of sect. Sturtia and sect. Hibiscoidea Tod. seeds were unpigmented and invisible to the naked eye, while pigmented, macroscopically visible lysigenous cavities occurred in all the sect. Grandicalyx (Fryxell) Fryxell seeds. HPLC (high performance liquid chromatography) analysis revealed that sect. Sturtia and sect. Hibiscoidea seeds did not contain detectable levels of terpenoid aldehydes, but that sect. Grandicalyx seeds contained gossypol.