Aims

In recent years, the application of large amounts of potash fertilizer in apple orchards leads to worsening KCl stress. Strigolactone (SL), as a novel phytohormone, reportedly participates in plant tolerance to NaCl and drought stresses. However, the underlying mechanism and the effects of exogenous SL on the KCl stress of apple seedlings remain unclear.

Methods

We sprayed different concentrations of exogenous SL on Malus hupehensis Rehd. under KCl stress and measured the physiological indexes like, photosynthetic parameter, content of ROS, osmolytes and mineral element. In addition, the expressions of KCl-responding genes and SL-signaling genes were also detected and analyzed.

Results

Application of exogenous SL protected the chlorophyll and maintained the photosynthetic rate of apple seedlings under KCl stress. Exogenous SL strengthened the enzyme activities of peroxidase and catalase, thereby eliminating reactive oxygen species production induced by KCl stress, promoting the accumulation of proline, and maintaining osmotic balance. Exogenous SL expelled K⁺ outside of the cytoplasm and compartmentalized K⁺ into the vacuole, increased the contents of Na⁺, Mg²⁺, Fe²⁺, and Mn²⁺ in the cytoplasm to maintain the ion homeostasis under KCl stress.

Conclusions

Exogenous SL can regulate photosynthesis, ROS migration and ion transport in apple seedlings to alleviate KCl stress.

中文翻译：

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外源性独脚金减轻应力的KCl通过调节光合作用，ROS迁移和离子转运平邑甜茶

目的

近年来，在苹果园中大量施用钾肥导致KCl胁迫加剧。据报道，Strigolactone（SL）作为一种新型植物激素，参与了植物对NaCl和干旱胁迫的耐受性。然而，尚不清楚外源SL对苹果幼苗KCl胁迫的潜在机制和影响。

方法

我们在平邑甜茶上喷洒了不同浓度的外源SL 。在氯化钾胁迫下，测定其生理指标，如光合参数，活性氧（ROS），渗透压和矿质元素含量。此外，还检测和分析了KCl响应基因和SL信号基因的表达。

结果

外源SL的保护保护了KCl胁迫下苹果幼苗的叶绿素，并保持其光合速率。外源SL增强了过氧化物酶和过氧化氢酶的酶活性，从而消除了KCl胁迫诱导的活性氧生成，促进了脯氨酸的积累，并保持了渗透平衡。外源性SL将K ⁺排到细胞质外，并使K ⁺进入液泡，使Na ⁺，Mg 2 ⁺，Fe ²⁺和Mn ²⁺的含量增加，从而在KCl胁迫下维持离子稳态。

结论

外源SL可以调节苹果幼苗的光合作用，ROS迁移和离子转运，从而减轻KCl胁迫。