Effects of low-temperature stress on secondary metabolism in mosses exposed to simulated N deposition.

Background:Both nitrogen deposition and low-temperature stress (LTS) affect the secondary metabolism of plants, but few were known about the responses of secondary metabolism to combined LTS and nitrogen supply, especially for mosses. Aims:To investigate the effects of LTS on secondary metabolism in two mosses,Pogonatum cirratumsubsp.fuscatumandHypnum plumaeforme, under varied nitrate or ammonium supply rates. Methods:Indices of oxidative stress and secondary metabolism in two mosses that were subjected to different N application and LTS treatment were measured both before and after a period of 10-day recovery. Results:LTS-induced oxidative stress was exacerbated by combined N application. LTS inhibited superoxide dismutase (SOD) activity inP. cirratumsubsp.fuscatum, but inH. plumaeformeSOD activity it was insensitive. N application induced increases in L-phenylalanine ammonia-lyase activity in both mosses, but the consequent changes in phenylpropanoid profiles in the mosses differed. LTS only changed the phenylpropanoid profiles. Levels of triterpenes were also affected by both N supply and LTS. In addition, levels of some secondary metabolites remained relatively high after 10-day recovery from LTS. Conclusions:N supply altered the responses of secondary metabolism to LTS. Some secondary metabolites may be stress memory substances associated with LTS of the mosses, with between-species differences. [ABSTRACT FROM PUBLISHER]