Hemigossypol, a Constituent
in Developing Glanded
Cottonseed (Gossypium hirsutum)
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Abstract
Gossypol is a dimeric sesquiterpenoid first identified
in cottonseed,
but found in various tissues in the cotton plant including the seed.
From its first discovery, it was assumed that hemigossypol was the
biosynthetic precursor of gossypol. Previous studies established that
peroxidase (either from horseradish or from cottonseed) converts hemigossypol
to gossypol. However, hemigossypol has never been identified in healthy
cottonseed. In a temporal study using HPLC and LC-MS, hemigossypol
was identified in the developing cotton embryo. It was shown to concomitantly
accumulate until 40 days postanthesis (dpa) with gossypol and with
transcripts of δ-cadinene synthase and 8-hydroxy-δ-cadinene
synthase, genes involved in the biosynthesis of hemigossypol and gossypol.
After 40 dpa, hemigossypol and its biosynthetic gene transcript levels
declined, whereas the gossypol level remained almost unchanged until
the bolls were open. These results provide further evidence to support
the previous findings that establish hemigossypol as the biosynthetic
precursor of gossypol