Analysis of Chlorophyll Content in Mosses through Extraction in DMSO

Abstract

Dimethylsulfoxide (DMSO) appears to be a useful extractant of chlorophyll in mosses. DMSO extracts and acetone extracts of gametophytic shoots of Grimmia laevigata (Brid.) Brid. gave similar estimates of chlorophyll content. Advantages of DMSO included ease of preparation and ability to extract desiccated samples without hydration. However, proper incubation period for extraction in DMSO differed among five species of mosses and among long-term experimental treatments of one species. This suggests that the time course of extraction must be determined for each species and for different populations within species. DMSO extracts were not more stable than acetone extracts. Extraction in dimethylsulfoxide (DMSO) has proven useful for analysis of chlorophyll content in algae (Shoaf & Lium 1976) and in vascular plants (Hiscox & Isrealstom 1979). Potential advantages of this new technique include ease of preparation, stability of extracts, and non-aqueous nature. In contrast to extraction in acetone or methanol (Ar- non 1949; Bruinsma 1963; Strain et al. 1971), ex- traction in DMSO does not require maceration or filtration of samples. DMSO extracts of chlorophyll of vascular plants also appear to be stable for up to 24 hours after incubation, while acetone extracts lose significant amounts of chlorophyll during sim- ilar storage (Hiscox & Isrealstom 1979). The non- aqueous nature of extraction in DMSO is of special interest in the study of desiccation-tolerant plants, such as many mosses, in which analysis of desic- cated samples without rehydration is often desir- able. The main disadvantage of DMSO is that ex- traction, which is carried out under incubation at elevated temperature, follows a time course of one to several hours; and optimal period of incubation differs among plant materials (Hiscox & Isrealstom 1979). Extraction in DMSO appears not to have been applied to date to analysis of chlorophyll in bryo- phytes or in other desiccation-tolerant species. The following questions were therefore addressed: (1) Do extraction in DMSO and extraction in acetone give similar estimates of chlorophyll content in mosses? (2) Can desiccated moss be successfully ex- tracted? (3) Are DMSO extracts of chlorophyll from mosses stable? (4) Does proper length of incubation in DMSO differ (a) among species and (b) among populations of the same species grown under dif-