Grapevine (Vitis vinifera L.) is naturally affected by flower abscission in various extents depending on cultivars, meaning that flowers abort during their development. This abscission may be caused by both physiological and environmental factors. In this context, we focused on the analysis of carbon metabolism in the inflorescence during flower development using the sensitive Gewurtzraminer (GW)
... [Show full abstract] and the low sensitive Pinot noir (PN) cultivars grow in vineyards. In parallel, we optimized a protocol to obtain flowers under controlled conditions enabling to get inflorescences that mimic vineyard grown inflorescence development.
Numerous differences were detected between GW and PN i.e. male and female organs develop more precociously in PN than in GW. Carbohydrate (starch, sucrose, glucose and fructose) levels in inflorescences differ between the two cultivars during the whole of floral development, especially between stages 15 and 17, corresponding to the key male and female meiosis. At this stage, one of the main differences consist in the presence of starch in the ovules of PN, in the contrary of GW. The assay of carbohydrate related enzyme activities confirmed that between stages 15 and 17 PN and GW metabolize sugars differently. Besides, we have shown that photosynthesis occurs in the inflorescence with different intensities in PN and GW, in particular between stages 15 and 17. The greater tolerance of PN to flower abscission may thus result in different carbohydrate metabolism enabling to avoid sugar starvation during meiosis when environmental stress occurs.
In order to confirm the impact of sugar physiology during flower development, we did perturb carbohydrate metabolism acting on reserve accumulation in perennial organs and using both vineyard grown plants and fruiting cuttings. Our results indicate in both cvs. that reserve restoration during the year n conditions the number of inflorescences per plant and the number of flowers per inflorescence developing during the year n+1.