Phenolic inhibitors were preliminarily isolated from the normal and abortive litchi (Litchi chinensis Sonn.) ovules with a series of solvents, and then separated and purified by thin-layer chromatography (TLC), further isolated and identified with GC-MS, and finally checked with standards. p-Hydroxybenzoic acid (p-HBA) was isolated and identified from litchi ovules in this experiment for the first time. Determination of its biological activity showed that p-HBA was a very strong growth inhibitory substance. In abortive ovules, p-HBA content and IAA oxidase activity were much higher; IAA content was much lower than those in normal ovules (P<0.01). It is suggested that p-HBA may be involved in the regulation of litchi embryo development; high content of p-HBA may accelerate IAA oxidation and affect the balance of growth promoting and inhibitory substances, causing embryo abortion.
