2.3. GHQ (9) and gossypol (1) in the D genome of Gossypium and in commercial cottons G. thurberi is a member of the D genome of Gossypium. In a previous investigation of terpenoids in the young leaves of G. thurberi using TLC plates, only gossypol (1) was identified in this tissue (Stipanovic et al., 1977). Thus, terpenoids such as the sesquiterpenoid hemigossypolone (7) and the sesterterpenoids heliocides H 1, H 2, H 3 and H 4 (3–6) (Fig. 1) that are found in commercial Upland cottons (Gossypium hirsutum), as well as other members of Gossypium, were not found. To extend this investigation, several Gossypium accessions of the D genome available in the USDA Cotton Germplasm collection were grown in the greenhouse; leaves were collected, freeze dried, and ground. The ground tissue was extracted and immediately subjected to HPLC analysis; the results are shown in Table 3. As found previously, other sesquiterpenoids and sesterterpenoids normally in G. hirsutum were not detected in G. thurberi nor in most other members of the D genome. However, GHQ (9) was present in small amounts in these cottons. As previously reported (Stipanovic et al., 1977), within the D genome only the leaves of Gossypium gossypioides (Ulbrich) contained hemigossypolone (7) and heliocides (3–6); the leaves of other members of the D genome did not contain these terpenoids. In addition, the leaves of G. raimondii contained only gossypol (1) and the sesquiterpenoid, raimondal (8) (Fig. 1). Four commercial cultivars of G. hirsutum cotton also were analyzed (Table 4). GHQ (9) was not detected in these plants, but, as expected, gossypol (1), hemigossypolone (7) and heliocides H 1 – H 4 (3–6) were detected.

Published as part of Stipanovic, Robert, Puckhaber, Lorraine, Jr., James Frelichowski, Esquivel, Jesus, Westbrook, John, O'Neil, Mike, Bell, Alois, Dowd, Michael, Hake, Kater & Duke, Sara, 2016, Gossypolhemiquinone, a dimeric sesquiterpenoid identified in cotton (Gossypium), pp. 165-171 in Phytochemistry 122 on page 167, DOI: 10.1016/j.phytochem.2015.12.009, http://zenodo.org/record/10485477