Biomass composition explains fruit relative growth rate and discriminates climacteric from non-climacteric species.

To understand the mechanisms that link metabolism to phenotypes, which would help to target breeding strategies, eight fleshy fruit species were compared during development and ripening. Three herbaceous (eggplant, pepper, cucumber), three tree (apple, peach, clementine) and two vine (kiwifruit, grape) species were selected for their diversity. Fruit fresh weight and biomass composition including the major soluble and insoluble components were determined throughout fruit development and ripening. Best fitting models of fruit weight were used to estimate relative growth rate (RGR), which was significantly correlated with several biomass components, especially protein content (R=84) stearate (R=0.72), palmitate (R=0.72) and lignocerate (R=0.68). Moreover, the strong link between biomass composition and RGR was further evidenced by generalised linear models that predicted RGR with R-values exceeding 0.9. Fruit comparison also showed that climacteric fruit (apple, peach, kiwifruit) contained more non-cellulosic cell-wall-glucose and -fucose and starch than non-climacteric fruit. The rate of starch net accumulation was also higher in climacteric fruit. These results suggest that the way biomass is constructed has a major influence on performance, especially growth rate.