Vascular bundle xylem water transport repression and cell anatomical structure differences may lead to berry cracking near the proximal end

Abstract

Grape berries often crack near the proximal end, which may be related to water absorption and their cellular anatomical structure. To study the relationship between water absorption, cell anatomical structures, and berry cracking near the proximal end, 49 varieties were selected. Eighteen were prone to cracking near the proximal end, while 31 were resistant. An in vitro soaking experiment on ripe berries measured the difference in berry-cracking degrees among different varieties. In vitro staining was used to trace water absorption and paraffin sections were prepared to observe and analyze the structural parameters of different tissues. Results showed that the cracking rate and water uptake of the crack-prone berries were significantly higher than those of the crack-resistant berries. Fruit prone to cracking was characterized by a thinner cuticle, epidermis, and sub-epidermis. After staining, it was found that dye absorption was limited to the berry near the proximal end. Other cell size parameters may also lead to cracking near the proximal end. By tracing water transport and analyzing differences in cell structure characteristics among varieties, we speculated that the vascular bundle xylem water transport repression and differences in cell anatomical structures may have led to berry cracking near the proximal end. The reasons for berry cracking near the proximal end were preliminarily explained, providing theoretical support for further screening of crack-resistant varieties.