Isoenzime polymorphism in four races and one hybrid of Bactris gasipaes (Palmae)

The study of genetic diversity in peach palm (Bactris gasipaes K.) is impor tant for the breeding work on this palm and to corroborate the hypotheses o n its origins. For that purpose it is necessary to use alternative techniqu es to complement the morphological studies traditionally made. One of the t echniques that responds to that need is isozyme electrophoresis. The isozym es are biochemical markers of importance in the study of genetic variabilit y in plants of economic importance, because they are the primary products o f genetic expression. This work is an electrophoretic analysis on gels of p olyacrilamide to study phenetic relations using twelve isozymes on four rac es and an spontaneous hybrid of peach palm. The biological material used ca me from the germplasm bank from Los Diamantes Experimental Station, Guapile s-Costa Rica. Four races and a hybrid were selected from that collection. T hey represented different procedences with morphological differences as wel l as having particular geographical distribution patterns; they were: Tembe -Chapare (Bolivia-Bo), Para-Belem (Brasil-Bra), Utilis Guapiles (Costa Rica -CR), Tuira-Darien (Panama-Pa) and Yurimaguas (Peru-Pe). Five trees of each race and the Yurimaguas hybrid were studied. Different tissues were tried: leaf, adventitious roots, spines, masculine flowers and ripe fruits. An st andard native and discontinued method was established on a polyacrilamide m atrix for the analysis of twelve isozymes: (PRX, EST, ACP, DIA, G6PDH, ME, MDH, GOT, ADH, PGI, PGM and SOD). The amount of tissue used was 1.5 g, with 20 min clarification time at 15000 gravity value and a temperature of 4.de grees C. The protocol proposed by Baaziz & Saaidi (1988) was followed with a modification of concentration of the phosphate buffer solution from 0,005 M to 0. 1M with a 50 to 200 volts gradient. The root, flower and spine tis sue were difficult to homogenize because of their high fiber content. The f ruit has too much oil and starch, which distort the banding. For those reas ons they were discarted. The leaves were selected because they are easy to homogenize and are available all year round. The standardized electrophoret ic method allowed the effective use of ten of the twelve isozymes in the le af tissue. Those ten isozymes showed phenetic polymorphism and are consider ed useful polymorphic markers for genetic and phenetic diversity studies in Bactris gasipaes. A discriminant marker for the Utilis-Guapiles race was f ound with the PRX isozyme, which shows an additional locus only in material from that precedence. The conglomerate statistical analysis showed that th e races and hybrid studies can be placed in three groups: one is formed by Para and Tembe, the second one by Utilis and Tuira, and the hybrid Yurimagu as is a class by itself and although it seems a bit closer to Utilis-Tuira, it is suspected that has its origin from unknown parents. these results fi t previous morphological interpretations. A genetic analysis was not made b ecause of the small sample size, but methodological procedures were establi shed for future research projects using larger populations to study peach p alm isozyme electrophoretic diversity.