Total sterols in root-knot nematode Meloidogyne incognita infected cotton Gossypium hirsutum (L.) plant roots*

Two near-isogenic breeding lines of Gossypium hirsutum (L.) (upland cotton) were inoculated with eggs of Meloidogyne incognita (Kofoid and White) Chitwood (RKN) in greenhouse pots. One line was susceptible (ST-213) and the other was resistant (81-249) to RKN. Eight days after inoculation, roots of plants and their controls were analyzed for total sterols by GLC and GLC-MS. The total content in roots of uninoculated roots of susceptible plants was slightly higher than in the roots of uninoculated resistant plants, but significantly lower after inoculation. By comparison, the sterois in roots of the resistant line were significantly higher at 8 days after inoculation. The major sterols in both susceptible and resistant fines were stigmasterol, sitosterol and campesterol, with a lesser amount of cholesterol and a trace of stigmastanol. Because the amounts and distribution of the sterols were similar in susceptible and resistant lines, they do not appear to be a factor associated with RKN growth and development. Sitosterol was the most abundant sterol in RKN eggs which also contained lesser amounts of cholesterol and stigmasterol. However, no stanols were found in RKN eggs.