[Exogenous nitric oxide accelerates soluble sugar, proline and secondary metabolite synthesis in Ginkgo biloba under drought stress].

The effects of exogenous nitric oxide donor sodium nitroprusside (SNP) on substance metabolism of Ginkgo biloba leaves under drought stress were studied. The results showed that 250 micromol/L SNP (Fig.2) treatment under 35% relative soil water content (RSWC) stress (Fig.1) raised remarkably soluble sugar content (Fig.3), proline content (Fig.4), phenylalanine ammonia lyase (PAL) activity (Fig.5), flavonoids (Fig.6) and ginkgolides content (Fig.7) of G. biloba leaves. Hemoglobin, used as NO scavenger, counteracted the effects of SNP in raising the soluble sugar (Fig.3), proline (Fig.4), flavonoid (Fig.6), ginkgolide content (Fig.7) and PAL activities (Fig.5), which indicates that the effects of sodium nitroprusside were through the nitric oxide released from sodium nitroprusside. We propose from these results that the roles of flavonoids and ginkgolides are the same as those of soluble sugars and proline under drought stress. NO may alleviate the damage caused by drought stress through raising soluble sugar, proline, flavonoid and ginkgolide content.