No abstract

Self-incompatibility and compatibility of 65 citrus accessions were determined by pollen tube growth in the style. Lemon was self-compatible whereas the six pummelos and seven out of 11 its relatives were self-incompatible. Furthermore, among sour oranges and their relatives, two out of six accessions were, likewise, self-incompatible as were one out of five sweet orange and their relatives. Every yuzu and its relatives, except hyuga-natsu, were self-compatible. Of the mandarin and its relatives, 14 out of 28 accessions were self-incompatible, whereas calamondin, a kumquat relative, and Hedzuka daidai of diverse origin were self-compatible. Thirty-one out of 65 accessions used in this study were self-incompatible. Of the self-incompatible accessions, clementine and 'Ariake', a hybrid of navel orange and clementine, were crossincompatible. Thus, the incompatible genotypes of those two accessions were considered to be identical.

Fluorochrome staining with chromomycin A 3 (CMA) was used to characterize and compare the CMA banding patterns of chromosomes in 14 accessions of 12 species of major Citrus species. All accessions had 2n = 18 chromosomes. These chromosomes were classified into seven types based on the number and position of CMApositive bands: A: two telomeric and one proximal band, B: one telomeric and one proximal band, C: two telomeric bands, D: one telomeric band, E: without bands, F: one proximal band, and Dst: type D with a satellite chromosome. Each accession possessed two to six types of chromosomes and unique CMA banding patterns. The CMA banding patterns were 2B + 8D + 8E in C. medica,micrantha, 2B + 1C + 11D + 3E + 1F in C. macroptera, and 3B + 1C + 8D + 3E + 2F + 1Dst in C. hystrix.

Brassinolide (BR), a novel plant growth-regulating steroidal lactone, markedly retarded the abscission of leaf explants of Calamondin (Citrus madurensis Lour .), when dissolved in water and fed through the p etiole . B R was effective at concentrations as low as 0 .021µM, and showed a stronger effect than IAA which also retarded abscission . Trifluoperazine (TFP), an inhibitor of the calmodulin-calcium complex, accelerated abscission, and this acceleration could be counteracted by a simultaneous addition of IAA or BR, the effect of IAA being s tronger . B R in lanolin applied to the cut surface of the leaf blade of the explant showed a weaker abscission-retarding effect than that applied in water via the petiole. B R and IAA also markedly retarded the abscission of fruitlet explants of Calamondin .

No abstract