A CHROMOSOME ATLAS AND INTERSPECIFIC - INTERGENIC INDEX FOR LOTUS ANDTETRAGONOLOBUS (FABACEAE)

Basic chromosome numbers in Lotus are x = 5, 6, and 7. It is considere d that evolution has proceeded in the genus by means of a descending a neuploid series from an eight-chromosomed ancestor. Chromosome numbers for species of Tetragonolobus are based on x = 7. Somatic chromosome numbers are reported for 108 species and 38 varieties. The chromosome numbers for five species (L. hamatus Greene, 2n = 14, L. haydonii (Orc utt) Greene, 2n = 14, L. hintoniorum B.L. Turner, 2n = 14, L. mearnsii Britton, 2n = 14, L. utahensis Ottley, 2n = 14) and seven varieties ( L. argophyllus (Gray) Green var. argenteus Dunkle, 2n = 14, L. dendroi deus var. traskiae (Eastwood ex Noddin) Isely, 2n = 14, L. heermanii ( Durand et Hilgard) Greene var. orbicularis (Gray) Isely, 2n = 14, L. j unceus (Benth.) Greene var. biolettii (Greene) Ottley, 2n = 14, L. str igosus var. hirtellus (Greene) Ottley, 2n = 14, L. strigosus var. tome ntellus (Greene) Isely, 2n = 14, L. uliginosus ssp. vestitus (Lange) A . Pedersen, 2n = 12) are reported for the first time. Natural diploid, tetraploid, and hexaploid plants are reported for L. alpinus. Several species are reported as possessing B chromosomes. Mixoploidy is repor ted to occur in three species (L. alpinus, L. glacialis, L. glareosus) . In addition, chromosome numbers are given for plants regenerated fro m calluses grown in tissue culture having both heteroploidy, euploidy, and mixoploidy. Root nodules are reported with tetraploid and octoplo id cells in addition to the normal number of chromosomes. Trisomic ser ies have been partially developed in L. tenuis and L. uliginosus. Poly tene chromosomes were observed in suspensor cells of three species of Lotus. Feulgen cytophotometric measurements, to determine the DNA nucl ear content, were made for 16 species of Lotus and one species of Tetr agonolobus. The majority of the studies in Lotus concern the economic species L. corniculatus, L. tenuis, and L. uliginosus. Interspecific h ybridization was carried out in different combinations between diploid s, autoploids, and amphidiploids. Intergeneric hybrids were attempted by somatic hybridization, protoplast fusion, and asymmetric hybridizat ion between Lotus and other species (Glycine mar, Medicago sativa, Ory za sativa).