[Effects of arbuscular mycorrhizal fungi on metabolism of aroma substances in tobacco]. / ä¸›æžèŒæ ¹çœŸèŒå¯¹çƒŸè‰é¦™æ°”ç›¸å ³ç‰©è´¨ä»£è°¢çš„å½±å“.

Arbuscular mycorrhizal fungi (AMF) can promote nutrient absorption and improve stress resistance of host plants. The effects of AMF on aroma substance metabolism were rarely examined. In this study, we investigated the effects of AMF (Glomus mosseae) on glands and metabolism of aroma substances in tobacco leaves. The results showed that the density of gland hair and the relative expression of the glandular-specific lipid transporter gene NtLTP1, which was necessary to induce lipid secretion, were higher in the leaves of tobacco inoculated with AMF. The content of main aroma substances in tobacco leaves, such as carotenoids, chlorogenic acid and solanesol, were increased. Moreover, AMF inoculation increased the activities of phenylalanine ammonia-lyase (PAL) and polyphenol oxidase (PPO), the key aroma substance synthesis enzymes, and caused upregulation in the relative expression of phenylalanine transaminase, polyphenoloxidase, flavonoids alcoholase and squalene synthase encoding genes. In all, the symbiosis with G. mosseae could increase the abundance and secretory activity of glandular hairs and promote the synthesis of aroma substances in tobacco leaves.

[The role of nitric oxide in ethylene-induced stomatal closure in Vicia faba L].

The effects of nitric oxide (NO) and ethylene on Vicia faba L. stomatal movement were studied. The results showed that NO donor SNP (sodium nitroprusside) 10 micromol/L and ethylene 0.04% could induce stomatal closure distinctly and they could promote stomatal closure when treated together. When treated with AVG (an inhibitor of ethylene synthesis), c-PTIO (a specific scavenger of NO) and NaN(3) (an inhibitor of NR), the effects of NO- and ethylene-induced stomatal closure were inhibited but the inhibitor of nitric oxide synthase (NOS) had little effect. We presumed that there was coordinative effect between NO and ethylene in regulation of stomatal closure; ethylene could induce stomatal closure by regulating the production of nitrate reductase (NR)-dependent NO.

[Involvement of nitric oxide in regulation of salt stress-induced ABA accumulation in maize seedling].

Possible regulation of salt stress-induced ABA accumulation by nitric oxide (NO) in maize seedling was investigated. Both NO and ABA contents of maize leaves and root tips were increased in response to salt stress (Fig.1,2). Similar to the effects of salt stress, ABA contents of maize leaves and root tips were increased after the treatment of maize leaves with sodium nitroprusside (SNP, a nitric oxide donor) alone (Fig.3). Compared to the salt stress-induced ABA accumulation, this SNP-induced ABA increase was much faster, suggesting that NO may be an intermediate signal from salt stress to ABA accumulation. When NO production inhibitors L-NAME and NaN(3) treatments were applied, salt stress-induced ABA accumulation was lowered (Fig.4). Treatment with NO scavenger cPTIO also inhibited the salt stress-induced ABA increase (Fig.5). From these results it is deduced that NO is involved in regulation of ABA accumulation under salt stress.