A RAPID AND EFFICIENT METHOD FOR THE SCREENING OF ACID PHOSPHATASE-1 IN YOUNG TOMATO SEEDLINGS, AND FOR THE IDENTIFICATION OF ROOT-KNOT NEMATODE SPECIES USING MINIATURIZED POLYACRYLAMIDE-GEL ELECTROPHORESIS

A relatively rapid and highly sensitive miniaturized polyacrylamide gel electrophoresis technique is described for the analysis of certain isozymes from single cotyledons of tomato seedlings and from single females of the root-knot nematode (Meloidogyne spp.). Homogenates from single tomato cotyledons (7,14,21, and 28 days old) were electrophoresed and stained for acid phosphatase 1 (Aps 1) activity. Cotyledons from plants of all the above age groups showed good Aps 1 activity. Nondestructive screening for tomato Aps 1 is therefore feasible, using very small samples, from as young as 7-day-old tomato seedlings. This could be of important use in expediting root-knot nematode resistance (based on the Aps 1-linked resistance gene Mi) screening for breeding programs, or F1 testing for seed production purposes. In addition, the mini-polyacrylamide gel electrophoresis technique was useful for determination of the Aps 1 allelic contribution to the total enzyme activity. The system was also used to detect malate dehydrogenase and esterase isozyme activity from single adult females of the four common root-knot nematodes, Meloidogyne arenaria, M. hapla, M. incognita, and Mjavanica, with equally good results, enabling species discrimination.