The abundant class III chitinase homolog in young developing banana fruits behaves as a transient vegetative storage protein and most probably serves as an important supply of amino acids for the synthesis of ripening-associated proteins.
Analyses of the protein content and composition revealed dramatic changes in gene expression during in situ banana (Musa spp.) fruit formation/ripening. The total banana protein content rapidly increases during the first 60 to 70 d, but remains constant for the rest of fruit formation/ripening. During the phase of rapid protein accumulation, an inactive homolog of class III chitinases accounts for up to 40% (w/v) of the total protein. Concomitant with the arrest of net protein accumulation, the chitinase-related protein (CRP) progressively decreases and several novel proteins appear in the electropherograms. Hence, CRP behaves as a fruit-specific vegetative storage protein that accumulates during early fruit formation and serves as a source of amino acids for the synthesis of ripening-associated proteins. Analyses of individual proteins revealed that a thaumatin-like protein, a beta-1,3-glucanase, a class I chitinase, and a mannose-binding lectin are the most abundant ripening-associated proteins. Because during the ripening of prematurely harvested bananas, similar changes take place as in the in situ ripening bananas, CRP present in immature fruits is a sufficient source of amino acids for a quasi-normal synthesis of ripening-associated proteins. However, it is evident that the conversion of CRP in ripening-associated proteins takes place at an accelerated rate, especially when climacteric ripening is induced by ethylene. The present report also includes a discussion of the accumulation of the major banana allergens and the identification of suitable promoters for the production of vaccines in transgenic bananas.
Peumans
Willy J
WJ
Laboratory for Phytopathology and Plant Protection, Catholic University Leuven, 3001 Leuven, Belgium.
Proost
Paul
P
Swennen
Rony L
RL
Van Damme
Els J M
EJ
D000596:Amino Acids / Q000378:metabolism*; D002688:Chitinases / Q000096:biosynthesis / Q000378:metabolism*; D005030:Ethylenes / Q000494:pharmacology; D005638:Fruit / Q000187:drug effects / Q000254:growth & development / Q000378:metabolism*; D018507:Gene Expression Regulation, Developmental; D018506:Gene Expression Regulation, Plant; D043326:Glucan 1,3-beta-Glucosidase; D037601:Mannose-Binding Lectin / Q000096:biosynthesis; D028521:Musa / Q000235:genetics / Q000254:growth & development / Q000378:metabolism*; D009943:Organophosphorus Compounds / Q000494:pharmacology; D010940:Plant Proteins / Q000096:biosynthesis* / Q000235:genetics; D013549:Sweetening Agents; D013997:Time Factors; D001617:beta-Glucosidase / Q000096:biosynthesis
D000596:Amino Acids; D005030:Ethylenes; D037601:Mannose-Binding Lectin; D009943:Organophosphorus Compounds; D010940:Plant Proteins; D013549:Sweetening Agents; C003427:thaumatin protein, plant; C036216:ethylene; D002688:Chitinases; C119825:chitinase C; C110892:chitinase, class III; D001617:beta-Glucosidase; D043326:Glucan 1,3-beta-Glucosidase; C005073:ethephon