Aims : The current work aims to study berry shrivel in grapes (a grape-ripening disorder) in relation to vine water status and climatic conditions using physiological and histological approaches. Methods and results : Measurements of rachis hydraulic conductance on grapevine clusters (Vitis vinifera L.) and observations of the vascular tissues (xylem and phloem) using transmission electron microscopy were conducted on rachises from healthy clusters and clusters having berry shrivel (BS) symptoms during the season. BS intensity was largely dependent on the vine water status : BS was greater in vines without water stress than in vines with moderate to high water stress around veraison time. Preliminary results showed that rachis hydraulic conductance declined sharply after veraison but remained slightly higher in healthy clusters in comparison with clusters presenting BS symptoms. An important degradation of the primary phloem was observed in the rachises of BS clusters, with the appearance of hard, nonfunctional liber (secondary phloem) and a disorganization of the cell content in the phloem tissue. An alteration of the primary xylem was also observed in the middle of the rachis and in the secondary rachis ramifications. Conclusion : These results suggest that the decrease in sugar and water accumulation in BS berries would primarily be associated with a decline in rachis phloem functionality. Significance and impact of the study : The management of the vine water status plays a key role in berry shrivel development.
