[2] COLLECTION AND STORAGE OF LAND PLANT SAMPLES 23 [2] Collection and Storage of Land Plant Samples for Macromolecular Comparisons By KENNETH J. SYTSMA, THOMAS J. GIVNISH, JAMES F. SMITH, and WILLIAMJ. HAHN Introduction The plant molecular systematist is confronted with three major practi- cal issues when initiating a survey of land plants: collection of plant tissue (location, type of tissue, quantity, preservation, transport, etc.), method of macromolecule extraction, and molecular technique used. These three factors are closely intertwined, and each can, and often does, have an influence on the others. The practical issues discussed in this chapter must therefore be considered in the broader context of issues relating to macro= molecule isolation (see [12] in this volume) and the kind of molecular information to be obtained (see Section II in this volume). This chapter deals specifically with three practical issues encountered in large-scale macromolecular systematic studies of land plants: (I) obtaining the plant tissue (including sources, tissues, collection, preservation, per- mits, and vouchers); (2) transport of the plant tissue; and (3) storage of plant tissue or macromolecules. Attention will focus on those studies involving DNA, but also on proteins (namely, isozymes) when issues dealing with the latter differ from those involving DNA3 a Sources of Land Plant Samples Sources of land plant tissue have included field collections, botanical gardens and greenhouses, spores and seeds from seed banks or field col- lected, herbarium specimens, and fossils. In a cursory review of published macromolecular systematic studies on land plants, the great majority of DNA-based studies utilized field-collected tissue as the primary source and botanical gardens (and sometimes seed banks) as the secondary source. The exceptions include, for the most part, studies of agronomically impor- tant species and their immediate relatives that used greenhouse- or field- grown tissue as the primary source. In sharp contrast, slightly less than one-third of the isozyme-based studies utilized field-collected tissue, de- pending instead on greenhouse-grown tissue from field-collected seeds. i D. J. Crawford, "Plant Molecular Systcmatics." Wiley, New York, 1990. 2 R. W. Murphy, J. W. Sites, Jr., D. G. Buth, and C. H. Haufler, in "Molecular Systematics" (D. M. Hillis and C. Moritz, eds.), p. 45. Sinauer, Sunderland, Massachusetts, 1990. Copyright© 1993 by Amdemic Pre~ Inc. METHODSIN ENZYMOLOGY, VOL. 224 Allrishtsof t~oducfion in any form reserved.