Chlorophyll a Fluorescence: A Signature of Photosynthesis

A small but measurable fraction of the light absorbed by chlorophyll is re-emitted as lowerenergy photons, i.e., fluorescent light. The yield of fluorescence from chlorophyll associated with photosynthetic membranes varies in response to a multitude of factors. Scientists have designed creative ways to take advantage of chlorophyll fluorescence to study aspects of photosynthesis at every scale, from the biophysics of energy transfer between chlorophyll molecules to the effects of global change on ecosystem productivity. Truly, chlorophyll fluorescence analysis resides at the heart of contemporary research on photosynthesis. This fact, along with the development of affordable lab-based and field-portable fluorometers, has encouraged scientists to incorporate fluorescence analysis into their research. Unfortunately, however, chlorophyll fluorescence research has evolved in a decidedly disorganized fashion. Many photochemical processes are described by several similar but subtly different fluorescence parameters. Some fluorescence parameters capture more than one photochemical process without offering a means of distinguishing the driving influences. Practitioners disagree over the strict definitions of fundamental terms such as photoinhibition and nonphotochemical fluorescence quenching. To the uninitiated, navigating the literature that chlorophyll fluorescence analysis has generated must at times feel like venturing into a foreign land whose language grows more complex by the week and for which there is no phrase-book. Chlorophyll a Fluorescence: A Signature of Photosynthesis is an impressive work (although it is not that needed phrase-book). It is the 19th volume in Springer’s on-going Advances in Photosynthesis series, the best contemporary collection of works dedicated to photosynthesis. Its editors, Papageorgiou and Govindjee (also the series editor), succeeded in attracting contributions from the leading lights in the various subdisciplines that employ chlorophyll fluorescence analysis. The book is a superb resource, capturing the ‘‘state of the field’’ at the time in which it was written, replete with differing interpretations inherent to any active area of research. In particular, I appreciated the candid assessment of the strengths, drawbacks, and technical hurdles associated with fluorescence imaging. Fluorescence imaging is likely to grow in significance as technical capabilities continue to improve. In general, the book is organized well and maintains the high production quality evident in previous volumes in the series. Chlorophyll a Fluorescence: A Signature of Photosynthesis is not especially welcoming to the non-expert. The early introductory chapters are dense, introduce some new language to describe long-used parameters (perhaps further confusing matters), and discuss at length parameters which are not commonly used in the published literature. Some chapters, although titled as though they are reviews, acknowledge in their introductory remarks that they are not with phrases such as ‘‘only recent progress . . . [is] summarized in this chapter’’ or ‘‘this chapter is not a detailed account . . . to be used . . . as a manual.’’ For those in my subdiscipline, physiological ecology, interested in understanding chlorophyll fluorescence analysis, I suggest reading Chapters 11 (Schreiber), 29 (CavenderBares and Bazzaz) and then 22 (Adams and Demmig-Adams). This approach to the book introduces the instrumentation and underlying theory, the applications in the field, and then practical advice on how to collect robust, interpretable data in the field (along with common pitfalls to avoid). Although Chlorophyll a Fluorescence: A Signature of Photosynthesis may not wrestle coherence from the complexity of chlorophyll fluorescence analysis, it will nonetheless be of lasting significance as a compendium of the thoughts and work of many pioneers and prominent practitioners.—BARRY A. LOGAN, Bowdoin College, Department of Biology, 6500 College Station, Brunswick, Maine 04011.