Department of Agricultural, Forest and Food Sciences, University of Turin, Grugliasco, Italy.
Institute for Sustainable Plant Protection, National Research Council, Turin, Italy.
Plant J. 2022 Nov;112(4):1098-1111. doi: 10.1111/tpj.16000. Epub 2022 Oct 28.
To understand how grapevine sinks compete with each other during water stress and subsequent rehydration, carbon (C) allocation patterns in drought-rehydrated vines (REC) at the beginning of fruit ripening were compared with control vines maintained under drought (WS) or fully irrigated (WW). In the 30 days following rehydration, the quantity and distribution of newly fixed C between leaves, roots and fruits was evaluated through CO pulse-labeling and stable isotope ratio mass spectrometry. REC plants diverted the same percentage of fixed C towards the berries as the WS plants, although the percentage was higher than that of WW plants. Net photosynthesis (measured simultaneously with root respiration in a multichamber system for analysis of gas exchange above- and below-ground) was approximately two-fold greater in REC compared to WS treatment, and comparable or even higher than in WW plants. Maximizing C assimilation and delivery in REC plants led to a significantly higher amount of newly fixed C compared to both control treatments, already 2 days after rehydration in root, and 2 days later in the berries, in line with the expression of genes responsible for sugar metabolism. In REC plants, the increase in C assimilation was able to support the requests of the sinks during fruit ripening, without affecting the reserves, as was the case in WS. These mechanisms clarify what is experienced in fruit crops, when occasional rain or irrigation events are more effective in determining sugar delivery towards fruits, rather than constant and satisfactory water availabilities.
为了了解葡萄藤在水分胁迫及随后复水过程中如何相互竞争，比较了果实开始成熟时干旱复水（REC）葡萄藤与干旱（WS）或充分灌溉（WW）对照葡萄藤的碳（C）分配模式。在复水后的 30 天内，通过 13CO2 脉冲标记和稳定同位素比质谱法评估了新固定 C 在叶片、根系和果实之间的数量和分布。与 WS 植株相比，REC 植株将相同比例的固定 C 转移到浆果中，尽管这一比例高于 WW 植株。与 WS 处理相比，REC 植株的净光合速率（通过多室系统同时测量，用于分析地上和地下的气体交换）大约高出两倍，与 WW 植株相当，甚至更高。在 REC 植株中，最大限度地增加 C 同化和输送导致与两个对照处理相比，新固定 C 的量显著增加，复水后 2 天在根部，2 天后在浆果中，这与负责糖代谢的基因的表达一致。在 REC 植株中，C 同化的增加能够在不影响贮藏的情况下，满足果实成熟期间对根系的需求，这与 WS 中的情况相同。这些机制阐明了在水果作物中所经历的情况，即偶尔的降雨或灌溉事件更有效地决定了糖向果实的输送，而不是恒定和令人满意的水分供应。
