Novel ripening-specific cDNA clones from mango fruit.
Lycett G. W., Zainal Z. B., Los M., Findlay C. L., Tucker G. A.
Author Affiliation: Faculty of Agricultural and Food Sciences, University of Nottingham, Sutton Bonington Campus, Loughborough LE12 5RD, UK.
: 277-286
Abstract : A ?-ZAP cDNA library was constructed from mango (Mangifera indica) cv. Tommy Atkins fruits which had been induced to ripen with ethylene. The library was screened with a tomato ACC oxidase 1 (ACO) cDNA. A clone (pNY601) was isolated that appeared to encode the full amino acid sequence of ACO. Northern analysis showed that the corresponding message was expressed in untreated green fruits and in fruits after 24 hours of ethylene treatment, although it decreased in the later stages of ripening. A differential screen was then conducted to find ripening-specific clones. Two abundant clones (pNY608 and pNY642) and 4 less common clones (pNY602, pNY627, pNY633 and pNY634) were identified. None of these 6 clones was expressed in green fruits, although all of them increased after ethylene treatment. When the cDNA inserts were sequenced and translated, pNY608, pNY627, pNY633 and pNY642 showed no significant homology to protein sequences in the SWISSPROT database. However, pNY634 showed strong homology to a plastid chaperonin, and pNY633 showed strong homology to the Ypt3/Rab11 class of small GTPases. These substances have possible roles in extracellular and intracellular pathways. No clones related to known fruit ripening specific genes of tomatoes or other species were found during the differential screen.