CONICET | Buscador de Institutos y Recursos Humanos

"-L-Arabinofuranosidase, "- and $-D-xylosidase, and $-D-glucosidase activity was detected in the soluble fraction (S-F) extracted with water and in the NaCl-released fraction (NaCl-F) extracted with a high-salt concentration buffer from apple callus cultures. The activity was found to be differentially modulated by the addition of various plant growth regulators (PGRs) to calluses that had lost their requirement for specific PGRs (habituation phenomenon). "-L-Arabinofuranosidase activity was 93%, 130%, 126% and 186% higher in the NaCl-F from IAA-, IBA-, ABA- and GA3-treated callus than in that extracted from untreated callus while S-F "-L-arabinofuranosidase activity was only 71%, 24%, 55% and 66% higher, respectively. "-D-Xylosidase displayed low activity levels in both S-F and NaCl-F but 2iP-treated callus showed higher "-D-xylosidase activity in both fractions than the control. 2,4-D increased "-D-xylosidase activity by 110% NaCI-F but decreased it by 40% in the "- DXylosidase activity increased by 99% in S-F from 2iP-treated callus but slightly decreased in the NaCl- GA3-treated callus, NaCI-F $-D-xylosidase increased by 188%. S-F and NaCI-F from Picloramtreated callus showed undetectable or only noticeable "-L-arabinofuranosidase, "-D-xylosidase and $-D-xylosidase activity. Interestingly, $-D-glucosidase activity rose 28-fold in the S-F extracted Picloram-treated callus. $-D-glucosidase was the enzyme assayed that greatly increased its activity after 10 subcultures, and the addition PGR to the callus culture except for Picloram ABA decreased its activity, suggesting that enzyme may be associated with certain stress conditions, such as PGR starvation or Picloram addition. This is the first report on glycoside hydrolases fruit callus as modulated by different PGRs.