Expression patterns of cell wall-modifying genes from banana during fruit ripening and in relationship with finger drop

Few molecular studies have been devoted to the finger drop process that occurs during banana fruit ripening. Recent studies revealed the involvement of changes in the properties of cell wall polysaccharides in the pedicel rupture area. In this study, the expression of cell-wall modifying genes was monitored in peel tissue during post-harvest ripening of Cavendish banana fruit, at median area (control zone) and compared with that in the pedicel rupture area (drop zone). To this end, three pectin methylesterase (PME) and seven xyloglucan endotransglycosylase/hydrolase (XTH) genes were isolated. The accumulation of their mRNAs and those of polygalaturonase, expansin, and pectate lyase genes already isolated from banana were examined. During post-harvest ripening, transcripts of all genes were detected in both zones, but accumulated differentially. MaPME1, MaPG1, and MaXTH4 mRNA levels did not change in either zone. Levels of MaPME3 and MaPG3 mRNAs increased greatly only in the control zone and at the late ripening stages. For other genes, the main molecular changes occurred 1–4 d after ripening induction. MaPME2, MaPEL1, MaPEL2, MaPG4, MaXTH6, MaXTH8, MaXTH9, MaEXP1, MaEXP4, and MaEXP5 accumulated highly in the drop zone, contrary to MaXTH3 and MaXTH5, and MaEXP2 throughout ripening. For MaPG2, MaXET1, and MaXET2 genes, high accumulation in the drop zone was transient. The transcriptional data obtained from all genes examined suggested that finger drop and peel softening involved similar mechanisms. These findings also led to the proposal of a sequence of molecular events leading to finger drop and to suggest some candidates

MOUNTAIN BANANAS FROM THE FRENCH WEST INDIES

Banana production is a key economic resource in the French West Indies. It is essential that growers in this region enhance their sales by proposing new products—such as mountain bananas—in response to high market competition from other exporting regions where production costs are lower. The quality of mountain bananas is officially recognised in Europe on the basis of a real taste difference. All French West Indian bananas grown at altitudes over 250 m ASL according to specifications can be sold under the mountain banana label. Mountain banana features can be assessed via objective data. At harvest stage, mountain bananas are denser, bulkier and less susceptible to wound anthracnose, caused by Colletotrichum musae, than lowland bananas, probably because of their higher mechanical resistance. Sensorial differences have also been documented in ripe bananas. At the same harvest stage and under identical ripening conditions, mountain bananas have a firmer texture, more intense yellowish pulp, and higher sugar and aromatic compound contents. A jury taste test analysis confirmed the sensorial differences between lowland and mountain bananas. The results of a multisite study indicated that temperature and rainfall during bunch growth are the main factors that distinguish mountain bananas

Mountain Bananas From French West Indies: First Data of Physico-Chemical Characterization

In order to propose a 'mountain' banana on the French market, the physicochemical caracteristics of bananas, growing at two different altitudes (Low 50 m and High 300 m) in Martinique, French West Indies, were compared. At the same harvest stage, fruits from the high altitude were significantly heavier, bigger and had a higher density and firmness than fruits from the lower altitude. After ripening, the higher altitude fruits were firmer and their peel was harder than those of the fruits from the lower altitude. The fruits from the higher altitude had significantly higher total solids, soluble solids, glucose, and fructose contents than the lower altitude fruits

Synthesis of Studies on Polarized Valve Actuators for Internal Combustion Engine

International audienc

Very Compact Actuators for Camless Systems

International audienc

Very Compact Actuators for Camless Systems

International audienc