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

Abstract

In order to conserve the germination power of coffee beans, only a tiny portion of endosperm was excised for caffeine determination. These non-destructive, single-bean analyses of the low-caffeine coffee mutant Laurina ( C. arabica 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 genotypes (somaclones), (b) a markedly lower mean caffeine content (0.56–0.61% dry wt) in the somaclones than in the parent line (0.68–0.71%), and (c) a high correlation between the caffeine contents of the bean and cotyledons emerged from it. Hence, breeding for low-caffeine coffee will be facilitated in future by simply analysing the cotyledons for this character. The combination of “somaclones” and single-seed analysis may be a useful and general strategy 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-methyltransferase (NMT) activities catalysing the last two steps in caffeine biosynthesis. The related activities were much lower than of the cultivar Catuai indicating that the lr lr alleles of Laurina, responsible for the reduction in half the “normal” caffeine content, interfere with the synthesis and not with the catabolism of caffeine.