INTRODUCTION: Apoplastic barriers differentiated from the root endoderm play important roles in plant stress resistance and nutrient uptake, and the development of suberin lamellae has become a popular research topic in recent years.
RATIONALE: Hydroponic experiments with potassium concentrations ranging from 0.1 to 4.0 mmol∙L-1 were conducted, using the cultivated tobacco variety Zhongyan 100 as the experimental material, to explore the effects of different potassium supplies on the endodermal suberization and its physiological and molecular mechanisms.
RESULTS: Low potassium (0.1 mmol∙L-1) stress significantly enhanced the endodermal suberization: the absolute length of the fully suberized region ranged from 0-2 cm in the control to 4-6 cm, and the relative proportion increased from 0-15.0% to 33.2%-44.3%. These findings indicate that suberization is one of the key morphological adaptation mechanisms in tobacco under low potassium stress. Phenotypic analysis revealed that under low potassium stress, root elongation increased while plant biomass decreased, and the potassium ion content and accumulation in both the aboveground and root parts decreased. Additionally, the flow rate and potassium ion concentration in the xylem sap decreased, indicating reduced transport efficiency. Endogenous hormone analysis revealed that low potassium stress increased the abscisic acid (ABA) content in roots while suppressing ethylene and methyl jasmonate levels, forming a specific hormonal regulatory network. The transcriptome data further supported the molecular basis of suberization development, showing significant upregulation of genes related to suberin synthesis and transport (e.g., CYP86, GPAT, and ABCG) and their upstream positive regulatory factors (MYB36, MYB41, MYB92, and MYB93).
CONCLUSION: This study is the first to reveal that low potassium stress regulates the suberization developmental program of tobacco roots through ABA-mediated hormonal signaling reprogramming, providing a novel perspective for understanding the adaptation mechanisms of plants to potassium stress.
Fluorescence imaging of transverse sections of the endodermis development in tobacco roots under three potassium concentrations (bars=130 μm)
| 科 Family | 属数 Number of genus | 种数 Number of species | 占总种数比例 Percentage of total species (%) | 属 Genus | 种数 Number of species | 占总种数比例 Percentage of total species (%) |
|---|---|---|---|---|---|---|
| 鹅膏菌科Amanitaceae | 2 | 11 | 5.26 | 鹅膏菌属 Amanita | 10 | 4.78 |
| 小菇科 Mycenaceae | 2 | 12 | 5.74 | 丝盖伞属 Inocybe | 5 | 2.39 |
| 多孔菌科 Polyporaceae | 8 | 14 | 6.70 | 蜡蘑属 Laccaria | 5 | 2.39 |
| 红菇科 Russulaceae | 3 | 23 | 11.00 | 小皮伞属 Marasmius | 6 | 2.87 |
| 小菇属 Mycena | 11 | 5.26 | ||||
| 光柄菇属 Pluteus | 5 | 2.39 | ||||
| 红菇属 Russula | 17 | 8.13 | ||||
| 栓菌属 Trametes | 5 | 2.39 |