Accumulation of ENOD2-like transcripts in non-nodulating woody papilionoidlegumes

Japanese pagodatree (Styphnolobium japonicum IL.] Schott) and American yell owwood (Cladrastis kentikea Dum.-Cours.) Rudd are the first woody, non-nodu lating papilionoid legumes shown to possess putative early nodulin 2 (ENOD2 ) genes. ENOD2 cDNAs from Japanese pagodatree (807 bp) and American yelloww ood (735 bp) have 75% to 79% sequence identity to ENOD2 sequences and encod e deduced proteins that possess conserved ENOD2 pentapeptides (PPHEK and PP EYQ). Lower percentages of glucose and higher percentages of histidine and valine suggest that SjENOD2 and CkENOD2 are different from other ENOD2s. Hy bridization analyses indicate the clones represent ENOD2 gene families of t wo to four genes in Japanese pagodatree and American yellowwood genomes, an d ENOD2-like transcripts were detected in stems and flowers, as well as roo ts. Only roots of control species that nodulate, Maackia amurensis Rupr. & Maxim. and alfalfa (Medicago sativa), produced pseudonodules after treatmen t with zeatin or 2,3,5-triiodobenzoic acid, an auxin transport inhibitor. A ccumulation of MaENOD2 transcripts was enhanced during the first 10 d of tr eatment, but 2,3,5-triiodobenzoic acid and zeatin enhanced transcript accum ulation after 30 d in roots of Japanese pagodatree and American yellowwood. Characteristics that distinguish ENOD2 gene families in basal, non-nodulat ing woody legumes from other ENOD2 genes may provide new information about the function of these genes during symbiotic and non-symbiotic organ develo pment.