Dynamic Analysis of Growth, Water Balance and Sap Fluxes through Phloem and Xylem in a Tomato Fruit: Short-term Effect of Water Stress
Dynamic Analysis of Growth, Water Balance and Sap Fluxes through Phloem and Xylem in a Tomato Fruit: Short-term Effect of Water Stress
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DOI：
10.2525/ecb1963.42.225
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发表时间：
2004-09
期刊：
影响因子：
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通讯作者：
T. Araki;Toshihiko Eguchi;T. Wajima;S. Yoshida;M. Kitano
中科院分区：
文献类型：
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作者：
T. Araki;Toshihiko Eguchi;T. Wajima;S. Yoshida;M. Kitano
为了研究番茄植株对水分胁迫的短期响应，研究了水分充足和亏水条件下果实生长动态和水分平衡。在水分充足的条件下，大部分（84%）花梗汁液流向果实，用于果实膨胀，剩下的（16%）通过果实和花萼的蒸腾作用流失。果实水分平衡的最主要组成部分是韧皮部汁液通量，因为输送到果实中的大部分（即70%）汁液是由韧皮部运输带来的。另一方面，木质部运输对果实膨胀的贡献较小，对水分胁迫的敏感性较大。水分亏缺条件下，果实生长速率被抑制至水分充足植株的36%，而韧皮部汁液流入果实的影响较小。水分亏缺条件下木质部液倒流频繁，全天木质部液的净流入量几乎为零。在水分胁迫下，韧皮部运输完全维持了果实的生长。本研究通过韧皮部和木质部运输对水分胁迫的不同响应，定量地证明了水分亏缺导致果实体积小、糖浓度高。
In order to examine the short-term response of tomato (Lycopersicon esculentum Mill.) plants to water stress, we investigated the dynamics of fruit growth and water balance in growing fruits under the well-watered and the water deficit conditions. Under the well-watered condition, most (84%) of pedicel sap flux toward the fruit contributed to fruit expansion, and the residual (i.e. only 16%) was lost by transpiration from the fruit and its calyx. The most dominant component of the fruit water balance was the phloem sap flux, since a major part (i.e. 70%) of the sap delivered into the fruit was brought by phloem transport. On the other hand, xylem transport made a lesser contribution to the fruit expansion and exhibited larger susceptibleness to water stress. Under the water deficit condition, the fruit growth rate was depressed to 36% of well-watered plants, while phloem sap influx to the fruit was less affected. Xylem sap backflow occurred frequently under the water deficit condition, and the net influx of xylem sap during the whole day was nearly zero. The phloem transport solely sustained the fruit growth under water stress. This study quantitatively demonstrated that water deficit results in smaller fruits with higher sugar concentrations through different responses of phloem and xylem transport to water stress.