13 Plant Telomeres

Abstract

Plants have served as important experimental organisms in the development of genetics and cytogenetics. This is due in part to historical circumstances, and in part to the agricultural interest in manipulating plant traits. The prominence of plant research also stems from the suitability of plants for cytological observation of the chromosomes and the facility with which transmission genetics can be conducted with plant material. Experiments using plants have played an important part in the study of the chromosome element that is the focus of this monograph.

I begin by briefly reviewing McClintock’s studies that helped define the telomere as an essential chromosomal element. I then turn toward more recent studies defining the molecular structure of telomeres in the flowering plants (angiosperms). In large part, this molecular work has a cytogenetic emphasis. Much of the current work in the plant telomere field concerns telomere cytology and genetic mapping. Experimenters are returning to the roots of telomere studies by taking advantage of the genetics and cytology available in plant systems.

McCLINTOCK’S EARLY STUDIES ON TELOMERES IN MAIZE
The discovery of the unique properties of native chromosome ends was based on observation of the behavior of broken chromosome ends in Drosophila and maize (see Gall, this volume). The paucity of terminal deletions recovered after X-ray-induced breakage of Drosophila chromosomes (for review, see Muller 1938; see also Roberts 1975) led Muller to propose that the “terminal gene” (i.e., telomere) “must have a special function, that of sealing the end of the chromosome” (Muller 1938)...