Expression of MADS genes in harvested banana fruit in relation to finger drop

Banana finger drop is a dislodgement of individual fruits from the hand at the pedicel area. Recent findings led us to suggest developmental cues as additional factors, beside ethylene, acting to control the finger drop process. Assuming that this developmental control involved MADS-box components as shown in other fruit, we analyzed here the MADS-box gene expression in the median (control zone, CZ) and pedicel rupture (drop zone, DZ) areas of the peel tissue from banana harvested at different physiological stages. In immature fruits, the mRNA level of MaMADS1, MaMADS2 and MaMADS6 genes were transitorily enhanced in DZ as compared to control. In early mature green fruit, MaMADS2 and MaMADS5 mRNA were highly and transitorily induced in the DZ, with a peak observed at day 2, as compared to the CZ. MaMADS2, MaMADS3 and MaMADS4 mRNA accumulated at comparable levels in both zones. In late mature green fruit, all MaMADS genes were transiently and differentially induced according to the peel zone, except MaMADS6 that increased slightly without any marked change in CZ and DZ. The MaMADS3 mRNA level was comparable in both zones while that of MaMDAS4 was enhanced in DZ. In banana fruit, MaMADS box genes may participate in this sequence of events with MaMADS2 and MaMADS4, and to a lesser extent MaMADS5, being associated with finger drop. They act sequentially to control the process, with MaMADS2 and MaMADS5 beginning earlier and MaMADS4 acting later. Findings offer insights regarding upstream regulatory factors and roles of MADS genes associated with finger drop. For improving banana quality traits, comparative analysis of MADS box genes expression enables selecting candidate genes for molecular marker identification. Next steps may (i) identify related molecular marker(s) and (ii) validate these markers via genetic association studies on a segregating population

What controls fleshy fruit acidity? A review of malate and citrate accumulation in fruit cells

International audienceFleshy fruit acidity is an important component of fruit organoleptic quality and is mainly due to the presence of malic and citric acids, the main organic acids found in most ripe fruits. The accumulation of these two acids in fruit cells is the result of several interlinked processes that take place in different compartments of the cell and appear to be under the control of many factors. This review combines analyses of transcriptomic, metabolomic, and proteomic data, and fruit process-based simulation models of the accumulation of citric and malic acids, to further our understanding of the physiological mechanisms likely to control the accumulation of these two acids during fruit development. The effects of agro-environmental factors, such as the source:sink ratio, water supply, mineral nutrition, and temperature, on citric and malic acid accumulation in fruit cells have been reported in several agronomic studies. This review sheds light on the interactions between these factors and the metabolism and storage of organic acids in the cell

Inhibition of apricot ethylene biosynthesis by CO2

National audienceDue to a large amount of 'Bergeron' apricot (Prunus armeniaca L.) production (around 70 000 tons, nearly 50% of the French apricot production), this variety is frequently commercialized after cold storage at 1°C. Problem of chilling-injuries and/or quick evolution after cold storage are observed. Treatment with an ethylene inhibitor combined with a higher storage temperature could be a solution to maintain fruit quality up to the consumption. The objective of this study was to evaluate the practical and theoretical impact of CO2 treatment during a short storage period at 10°C

Is there a relationship between ethylene production of bananas ripened on the plant and the length of the fruit growth period prior to ripening onset ?

Introduction. Une étude récente menée en laboratoire a mis en évidence une corrélation négative entre la production d'éthylène des bananes pendant leur maturation et leur durée de vie commerciale. L'objectif de notre travail a été de savoir s'il existait une relation entre la production d'éthylène du fruit pendant la maturation et la durée de la période de croissance en vert, avant que la maturation ne commence. Une réponse positive serait importante pour une sélection précoce lors de programmes de création variétale. Matériel et méthodes. Quatre variétés présentant différentes durées de phase de croissance ont été étudiées. La biosynthèse d'éthylène a été suivie par la production d'éthylène et la teneur en acide 1-aminocyclopropane-1-carboxylique (ACC), le précurseur immédiat de cette hormone, pendant le développement et la maturation du fruit. Les fruits ont totalement mûri sur le bananier. Résultats. La production d'éthylène a commencé à être détectée au stade de coloration tournant du fruit. Pour les quatre variétés étudiées, elle a été maximale au stade "complètement jaune soutenu, y compris les extrémités". Deux variétés, Sowmuk et IDN 110, ont eu les niveaux de production d'éthylène les plus élevés [respectivement, des maxima de (26 et 19) [mu]L d'éthylène-h-1. kg-1 de poids frais]. Les variétés Galéo et Grande Naine ont eu des productions plus faibles. Les deux variétés les plus productives en éthylène sont celles qui ont présenté une forte augmentation de leurs teneurs en ACC libre juste avant la maturation. Conclusion. Il n'y a pas de corrélation entre la production d'éthylène de bananes mûries sur le bananier et la longueur de la phase de croissance avant le début de la maturation. (Résumé d'auteur

Contrasting effects of polysaccharide components on the cooking properties of Roots, Tubers and Bananas (RTBs)

Background: Consumer preferences for boiled or fried pieces of roots, tubers and bananas (RTBs) foodstuffs are mainly related to their texture. Different raw and cooked RTBs were physiochemically characterised to determine the effect of biochemical components on their cooking properties. Results: Firmness in boiled sweetpotato increases with sugar and amylose contents but no significant correlation was observed between other physicochemical characteristics and cooking behaviour. Hardness of boiled yam can be predicted by dry matter (DM) and galacturonic acid (GalA) levels. For cassava, no significant correlation was found between textural properties of boiled roots and DM, but amylose and Ca2+ content were correlated with firmness, negatively and positively, respectively. Water absorption of cassava root pieces boiled in calcium chloride solutions was much lower, providing indirect evidence that pectins are involved in determining cooking quality. A highly positive correlation between textural attributes and DM was observed for fried plantain, but no significant correlation was found with GalA, although frying slightly reduced GalA. Conclusion: The effect of main components on texture after cooking differs for the various RTBs. The effect of global DM and major components (i.e., starch, amylose) is prominent for yam, plantain and sweetpotato. Pectins also play an important role on the texture of boiled yam and play a prominent role for cassava through interaction with Ca2+