ISHS Acta Horticulturae 455: V International Mango Symposium
NOVEL RIPENING-SPECIFIC CDNA CLONES FROM MANGO FRUIT |
| Authors: | G. W. Lycett, Z. Zainal, M. Los, C. L. Findlay, G. A. Tucker |
| Abstract:
A  -ZAP™ cDNA library was made from Mangifera indica L. cv.
Tommy Atkins fruit that had been induced to ripen with ethene.
The library was screened with a tomato ACC oxidase I (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 fruit and fruit after 24 hours in ethylene but declined in the later stages of ripening.
A differential screen was then carried out to find ripening-specific clones. Two abundant types of clone were found as exemplified by the longest plasmid "type clone" for each class: pNY608, and pNY642. In addition, four rare or types (pNY602, pNY627, pNY633 and pNY634) were found. None of these six clones showed any expression in green fruit but all exhibited an increase in level after ethene treatment. When the cDNA inserts were sequenced and translated, pNY608, pNY627, pNY633 and pNY642 gave no convincing match to the SWISSPROT protein sequence database. However, pNY634 showed strong homology to a plastid chaperonin and pNY622 showed very strong homology to the Ypt3/Rab11 class of small GTPases. These have possible roles in extracellular and intracellular secretory pathways. It is also interesting to note that no clones related to known fruit ripening specific genes of tomato or other species were found during the differential screen. | |
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