Non-destructive analysis of natural variability in bean caffeine content of Laurina coffee

In order to conserve the germination power of coffee beans, only a tiny por tion of endosperm was excised for caffeine determination. These non-destruc tive, single-bean analyses of the low-caffeine coffee mutant Laurina (C. ar abica cv. laurina) revealed (a) a variation of the caffeine content from 0. 36 to 1.08%, with lowest values found in the tissue culture-derived genotyp es (somaclones), (b) a markedly lower mean caffeine content (0.56-0.61% dry wt) in the somaclones than in the parent fine (0.68-0.71%), and; (c) a hig h correlation between the caffeine contents of the bean and cotyledons emer ged from it. Hence, breeding for low-caffeine coffee will be facilitated in future by simply analysing the cotyledons for this character. The combinat ion of "somaclones" and single-seed analysis may be a useful and general st rategy to tailor the phytochemical pattern of plants. Additionally, the young leaflets of Laurina, equally to the seeds furnished with a low caffeine-content, were studied with respect to the N-methyltran sferase (NMT) activities catalysing the last two steps in caffeine biosynth esis. The related activities were much lower than of the cultivar Catuai in dicating that the Ir Ir alleles of Laurina, responsible for the reduction i n half the "normal" caffeine content, interfere with the synthesis and not with the catabolism of caffeine. (C) 1998 Elsevier Science Ltd. All rights reserved.