Morphological and molecular characterization of fibrousness in mangoes

Mango (Mangifera indica L.) is one of the most important fruit trees in tropical and subtropical regions. The fruit is a drupe with a fleshy edible mesocarp. The seed is covered with a hard fibrous endocarp. The fibers penetrate from the endocarp into the mesocarp. Fibers characterize all mango cultivars, but some are considered more fibrous then others. High quality cultivars have short and soft fibers, but in fibrous cultivars they are harder and may fill the entire mesocarp, negatively influencing customers’ satisfaction. The aim of this study was the characterization of fiber formation in fibrous and non-fibrous accessions morphologically and histologically in ripened fruits. Two types of fibers were detected: thick and long fibers driven from the fruit stalk, extending the entire length of the fruit just under the peal, and shorter fibers that emerge from the endocarp. Fibers developed in the mesocarp of fibrous accessions have larger cross section areas relative to those of non-fibrous cultivars. However, the main difference is probably the fiber’s rigidity. Next generation sequencing performed during fruit development and seed hardening of some “fibrous” and “non-fibrous” accessions, the mesocarp and endocarp tissues revealed selective differential gene expression. Our work sheds light on the differences between fibrous and non-fibrous cultivars, enabling a better understanding of the processes leading to fiber formation in the mesocarp. This information is valuable for developing markers for breeding of non-fibrous cultivars and for future biotechnological approaches to generate fibrous-free cultivars.