Characterization of Pyrus Species and Cultivars Using Gradient Polyacrylamide Gel Electrophoresis

Abstract

A chemical identification procedure previously used to identify apple clones was tried with pear species and clones. Following electrophoresis, the peroxidase, esterase, and acid phosphatase isozyme patterns on anionic polyacrylamide gradient gels were determined. These patterns were found to vary with the species and clone, but not to change, within a clone during the growing season. Thus, these patterns were considered to represent genetic characteristics. The patterns were used to identify 37 selected Pyrus accessions at the National Clonal Germplasm Repository, Corvallis, Oregon. All species tested were distinguishable using this system. All the accessions of P. calleryana selected from the NCGR collection were distinct: however, one clone from outside the collection had an identical pattern to one inside the collection. Among the Chinese pear clones (complex hybrids of P. ussuriensis × P. pyrifolia) tested, three pairs of clones had the same combination. This technique appears to have the potential to readily identify pear specimens, and could be an important aid in the characterization of germplasm material.

Characterization of Quince (Cydonia) Cultivars Using Polyacrylamide Gel Electrophoresis

“…In previous investigations of other genera [Corylus (1), Malus (20,23), Pyrus (8,21,22)] isozyme patterns that identified each clone remained constant throughout the year, and were not affected by the age of the plant from which the shoots were collected. This is attributed to the diversity of tissues found in stems, which not only include phloem, xylem and cambium, but also photosynthetic, active tis sues (7).…”

“…This area may contain addi tional information but was not considered useful for the purposes of this paper. Quince preparations yield gels with slightly stronger background, yielding slightly less distinct photographs, than those of pear (8,21) or apple (23) ~ and pear extracts yield slightly less distinct photographs than those of CoryIus (1). This is attributed to a need to tailor the trailing ion in the upper buffer (now glycine) by sub stituting a mix of anlino acids with variable pKa's.…”

“…One year old shoots were collected from December 1986 through August 1987. The protein extraction technique used for Cydonia was the same as that used in pear characterization (21). Stems were stored at -30°C ( -22°F) before extraction.…”

“…This treatment is known to induce polyphenol oxidase activity (7). Electrophoresis was performed on a multiple 16 cm (6.3 in) vertical slab electrophoresis cell (Model SE 700, Hoefer, San Francisco, California) using similar conditions [20 milianlperes with a 7.5 watts per gel upper limit~ gel thickness 1.5 mm (0.06 in)] as previously described (21)~ except that the cold room temperature was 3°C (37°F). The enzymic stains for per oxidase, esterase and acid phosphatase were done as de scribed by Shaw and Prasad (25), and phenol oxidase following Hare (14).…”

“…Chemical identification (fingerprinting) of plant species and cultivars has received increased attention (1,3,4,5,6,8,11,13,18,20,21,23,24,30,31) from plant breeders, the nursery industry, growers, and U. S. trade officials (1) because of the increased recognition of germplasm reserves and the importance of exact clonal identification. The Na tional Clonal Germplasm Repository (NCGR) system, col lects, maintains, identifies and characterizes clones of selected crop genera (16).…”