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Developmental changes in carbohydrate content and sucrose degrading enzymes in tuberising stolons of potato ( Solanum tuberosum )
Author(s) -
Ross Heather A.,
Davies Howard V.,
Burch Lindsay R.,
Viola Roberto,
McRae Diane
Publication year - 1994
Publication title -
physiologia plantarum
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.351
H-Index - 146
eISSN - 1399-3054
pISSN - 0031-9317
DOI - 10.1111/j.1399-3054.1994.tb02533.x
Subject(s) - stolon , invertase , sucrose , sucrose synthase , fructokinase , starch , fructose , solanum tuberosum , biochemistry , carbohydrate , biology , starch synthase , chemistry , botany , amylose , amylopectin
Tuberising stolon tips of potato ( Solanum tuberosum L. cv. Record) accumulate starch and sucrose but the hexose content, particularly fructose, declines rapidly. Similar changes occur in the region 2 cm behind the swelling apex but the decline in glucose is far more pronounced than in the developing tuber. Tuberisation is characterised by an apparent switch from an invertase‐dominated sucrolytic system (both acid and alkaline invertases [EC 3.2.1.26] are present) to one dominated by sucrose synthase (EC 2.4.1.13). Sucrose synthase and fructokinase (EC 2.7.1.4) activities were, at a maximum, ca 10‐ and 5‐fold higher, respectively in the swelling stolon tip compared with the non‐tuberising region. At the highest starch contents attained, the starch level in the young developing tuber was approximately double that in the adjacent non‐tuberising stolon region. Immunoblots revealed that developmental changes in sucrose synthase. fructokinase and alkaline invertase polypeptides corresponded with enzyme activities. Antibodies raised against the N‐terminal amino acid sequence of a soluble invertase purified from mature tubers did not detect significant quantities of a polypeptide in stolons and young, developing tubers. Antibodies raised against an in vitro expression product of an apoplastic invertase cloned from a leaf cDNA library detected a polypeptide in developing tubers but not in mature ones. However, expression of the protein did not correlate well with acid invertase activity during early tuber formation.