GIBBERELLIN CONCENTRATION AND TRANSPORT IN GENETIC LINES OF PEA - EFFECTS OF GRAFTING

Effects of the Na and Le loci on gibberellin (GA) content and transport in pea (Pisum sativum L.) shoots were studied. GA1, GA8, GA17, GA19, GA20, GA29, GA44, GA8 catabolite, and GA29 catabolite were identified by full-scan gas chromatography-mass spectrometry in extracts of expanding and fully expanded tissues of line C79-338 (Na Le). Quantification of GAs by gas chromatography-single-ion monitoring using deuterated internal standards in lines differing at the Na and Le alleles showed that na reduced the contents of GA19, GA20, and GA29 on average to <3% and of GA1 and GA8 to <30% of those in corresponding Na lines. In expanding tissues from Na le lines, GA1 and GA8 concentrations were reduced to approximately 10 and 2%, respectively, and GA29 content increased 2- to 3-fold compared with those in Na Le plants. There was a close correlation between stem length and the concentrations of GA1 or GA8 in shoot apices in all six genotypes investigated. In na/Na grafts, internode length and GA1 concentration of nana scions were normalized, the GA20 content increased slightly, but GA19 levels were unaffected. Movement of labeled GAs applied to leaves on Na rootstocks indicated that GA19 was transported poorly to apices of na scions compared with GA20 and GA1. Our evidence suggests that GA20 is the major transported GA in peas.