Use of suppression subtractive hybridization approach to identify genes differentially expressed during early banana fruit development undergoing changes in ethylene responsiveness

Little is known about the early green developmental stage of banana fruit before the commercial harvesting stage. In this study, we demonstrate that banana fruit (cv Cavendish) grown under our pedoclimatical conditions undergoes changes in ethylene responsiveness between 40 (immature fruit unable to respond to ethylene), 60 and 90 DAF (days after flowering; early and late mature fruit able to respond to ethylene, respectively). Further, we have combined subtractive suppression hybridization (SSH) and macro-array hybridization to construct four different SSH libraries comprising a total of 3072 clones and identify 876 clones that are differentially expressed during fruit ripening. Some of these positive clones were partially sequenced to generate ESTs. Sequence analysis revealed that 163 clones on 177 (92%) presented a high similarity with different genes in the database and were related to various plant mechanisms. Northern blot analysis and real-time quantitative PCR conducted on 24 selected clones showed that the subtraction worked properly and led to get more insights into the early green developmental stages of banana. These genes will contribute to increase pools of public EST collections of banana for identification of candidate genes and the providing of molecular markers usable to improve banana fruit quality throughout conventional breeding or biotechnology approaches.