College of Resources and Environment, Southwest University, Chongqing, 400716, China.
Vegetable and Flower Institute of Chongqing Academy of Agricultural Sciences, Chongqing, 401329, China.
BMC Plant Biol. 2019 Apr 8;19(1):130. doi: 10.1186/s12870-019-1706-1.
Potassium is a nutrient element necessary for tobacco growth. Tobacco leaves with high potassium content are elastic and tough, rich in oil. And the same time, potassium can also improve the scent and aromatic value of flue-cured tobacco by regulating the synthesis of aromatic hydrocarbons in leaves.. It is an important quality indicator for flue-cured tobacco. However, the potassium concentration in tobacco leaves in most areas of China is generally lower than the global standard for high quality tobacco. Two tobacco genotypes were grafted to each other under different potassium levels to test whether potassium content and plant growth can be improved by grafting in tobacco.
The growth of tobacco in all treatments was inhibited under potassium starvation, and grafting significantly alleviated this potassium stress in 'Yunyan 87'. The trends in whole plant K uptake and K transfer efficiency to the leaves corresponded to the growth results of the different grafts. The nutrient depletion test results showed that the roots of 'Wufeng No.2' had higher K absorption potential, K affinity, and K inward flow rate. K enrichment circles appeared at the endoderm of the root section in the energy dispersive X-ray figure, indicating that the formation of Casparian strips may be partly responsible for the lower rate of lateral movement of K in the roots of 'Yunyan 87'. Gene expression analysis suggested that energy redistribution at the whole plant level might constitute one strategy for coping with potassium starvation. The feedback regulation effects between scion 'Wufeng No.2' and rootstock 'Yunyan 87' indicated that the transmission of certain signaling substances had occurred during grafting.
'Wufeng No.2' tobacco rootstock grafting can increase the K uptake and transport efficiency of 'Yunyan 87' and enhance plant growth under potassium stress. The physiological mechanism of the improved performance of grafted tobacco is related to higher K uptake and utilization ability, improved xylem K loading capacity, and up-regulated expression of genes related to energy supply systems.
钾是烟草生长所必需的营养元素。钾含量高的烟叶弹性和韧性好，油分足。同时，钾还可以通过调节烟叶中芳香烃的合成来改善烤烟的香气和香气值。它是烤烟的一个重要质量指标。然而，中国大部分地区烟叶的钾浓度普遍低于优质烟叶的全球标准。本研究通过在不同钾水平下将两个烟草基因型进行嫁接，以测试嫁接是否可以提高烟草的钾含量和植物生长。
在低钾胁迫下，所有处理的烟草生长均受到抑制，嫁接显著缓解了‘云烟 87’的这种钾胁迫。植株对钾的吸收和向叶片转移的效率与不同嫁接的生长结果一致。养分耗尽试验结果表明，‘武峰 2 号’根系具有更高的钾吸收潜力、钾亲和力和钾内流率。在能谱图中，根段的内皮层出现钾富集环，表明 Casparian 条带的形成可能部分导致‘云烟 87’根系中钾侧向运动速率较低。基因表达分析表明，植株整体水平的能量再分配可能是应对低钾胁迫的一种策略。接穗‘武峰 2 号’和砧木‘云烟 87’之间的反馈调节效应表明，嫁接过程中发生了某些信号物质的传递。
‘武峰 2 号’烟草砧木嫁接可以提高‘云烟 87’的钾吸收和转运效率，增强钾胁迫下的植株生长。嫁接烟草表现改善的生理机制与更高的钾吸收和利用能力、改善的木质部钾装载能力以及与能源供应系统相关的基因表达上调有关。
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