Production of border cells and colonization of maize root tips by Herbaspirillum seropedicae are modulated by humic acid
Production of border cells and colonization of maize root tips by Herbaspirillum seropedicae are modulated by humic acid
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DOI：
10.1007/s11104-017-3267-0
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发表时间：
2017-08-01
期刊：
影响因子：
4.9
通讯作者：
Olivares, Fabio Lopes
中科院分区：
文献类型：
--
作者：
Canellas, Luciano Pasqualoto;Olivares, Fabio Lopes
植物对陆地生态系统的适应涉及有机质和微生物群落之间复杂的根际相互作用。边界细胞构成了植物-土壤生态系统中的第一个生存边界，在响应不同生物和非生物条件的环境感知和信号传递中发挥着重要作用。本研究采用不同浓度腐植酸(0、12、42、143和500 mg L-1)浸泡玉米幼苗48h，研究了腐植酸对玉米根尖BCS释放的影响及其对血清型除草剂侵染的影响。用光学显微镜和扫描电子显微镜研究了边缘细胞与根尖血吸虫之间的结构相互作用。腐植酸(HA)显著增加了BCS从根尖的释放，并呈钟形剂量-反应曲线；BCS的释放在143mgHA L-1时最高，并在显微镜下得到证实。用荧光显微镜观察了外源腐植酸(14 3 mg L-1)和不加外源腐植酸(14 3 mg L-1)对绿色荧光蛋白标记的血清型链球藻RAM10菌株根部定殖的影响。BC释放量的增加导致根尖有高密度的重氮菌，细菌有时聚集在粘液和腐殖酸颗粒中，从而提高了它们的生存能力。腐植酸引起的BC数量增加可能解释了先前的研究表明，草地根际、根面和内层中的H.seropedicae种群伴随着增加。H.seropedicae菌株RAM10在根冠和BCS上定殖的种群随着外源腐植酸的响应而增加。
The adaptation of plants to land ecosystems involves complex rhizosphere interactions between organic matter and microbial communities. Border cells (BC) constitute the first living boundary in plant-soil ecosystems and play an important role in environmental sensing and signaling in response to different biotic and abiotic conditions. In this study, we evaluate the effect of humic acid on the release of BCs and its impact on the colonization of Herbaspirillum seropedicae at maize root tips.Maize seedlings (1.0 +/- 0.05 cm root length) were immersed for 48 h in solutions with different concentrations of humic acid (0, 12, 42, 143 and 500 mg L-1). Light and scanning electron microscopy were used to evaluate the structural interaction between border cells and H. seropedicae at the root tips.The release of BCs from root tips was significantly increased by humic acid (HA) application and exhibited a bell-shaped dose-response curve; the highest release of BCs occurred at 143 mg HA L-1 and was confirmed by microscopy. The colonization of roots by H. seropedicae strain RAM10 (tagged with green fluorescent protein, GFP) was monitored by epifluorescence microscopy with and without exogenous humic acid (143 mg L-1). Increased BC release resulted in a high density of diazotrophic bacteria at root tips, and bacteria sometimes aggregated with mucilage and humic acid particles, thus enhancing their viability. Increased BC numbers in response to humic acid might explain previous studies showing a concomitant increase in H. seropedicae populations in the rhizosphere, rhizoplane, and endosphere of grasses.The population of H. seropedicae strain RAM10 colonizing root caps and BCs increased in response to exogenous humic acids.