【作者】 吉云秀；

【导师】 黄晓东； 丁永生；

【作者基本信息】 大连海事大学 ， 环境科学， 2008， 博士

【摘要】 本文从含1-氨基环丙烷-1-羧酸(ACC)脱氨酶的植物促生菌(PGPR)分离及特性鉴定入手,对其提高植物抗盐、抗旱、抗涝、抗石油污染胁迫性进行了研究,为油污染海岸带的植物修复奠定了基础,同时也为日益严重的盐渍化、干旱、水涝、油污染土壤提供了一种环境友好、经济有效提高作物产量的方法。本文以ACC为唯一氮源,从油污染盐生植物翅碱蓬的根际土中快速分离得到4株含ACC脱氨酶活性的PGPR,经16s rDNA序列分析,鉴定为来自不同的属,分别为假单胞菌属S1,柠檬酸杆菌属S2,肠杆菌属S3,克雷伯氏菌属S4。生长曲线测定结果表明,4株分离菌株在以ACC为唯一氮源的0-3%NaCl或pH=7.5-8.5的ADF培养液中均能不同程度的生长,菌株间的生长差异程度与其ACC脱氨酶活性相一致,其中菌株S1的ACC脱氨酶活性最高。研究发现,pH=8.5或3%NaCl的盐分对菌株ACC脱氨酶活性有一定的抑制作用。无菌育种袋和未灭菌土壤盆栽试验结果表明,4株分离菌株均能不同程度地提高燕麦或黑麦草初生苗的抗盐性,其中菌株S1最显著,10g/kg NaCl比无NaCl时促生作用更大。Pearson相关性分析结果表明,ACC脱氨酶活性与植物生长参数之间具有极显著的正相关性,是缓解促生的主要因素而非植物生长素IAA。植物促生菌S1、S3和恶臭假单胞菌UW4,无论单菌接种还是双菌接种,均能显著地提高翅碱蓬抗盐抗旱抗涝性,双菌接种比单菌接种对提高抗盐性更显著,但单菌S1对缓解翅碱蓬受干旱或水涝胁迫的促生作用与双菌接种无显著差异。无论是燕麦还是黑麦草,盐、水涝或石油污染胁迫对植物地下根系的不利影响均大于对地上植株的影响,但接种植物促生菌S1均能显著地提高植物抗逆性,大大提高燕麦或黑麦草根际土的总石油烃降解率。胁迫动态跟踪试验结果表明,Fv/Fm值变化趋势与地上株高变化趋势均相符,故光系统Ⅱ(PSⅡ)的光化学效率——Fv/Fm值可以作为PGPR提高植物抗逆性的动态诊断指标。更多还原

【Abstract】 Isolation and identification of 1-aminocyclopropane-1-carboxylic acid (ACC) deaminase-containing plant growth-promoting rhizobacteria (PGPR), and enhancement of resistance to salt, drought, flooding and petroleum stress in plants were studied, which layed a foundation for phytoremediation of oil-contaminated coastal zone, and served as an environmentally-friendly and economical alternative to the enhancement of crop production in increasingly saline, dry, inudant and oil-contaminated soils.Four strains of ACC deaminase-containing PGPR were isolated from the oil-contaminated rhizosphere soils of Suaeda heteroptera Kitag, a kind of salty plant, based on the ability to utilize ACC as a sole nitrogen source. These four isolates were identified as Pseudomonas sp. S1, Citrobacter sp. S2, Enterobacter sp. S3 and Klebsiella sp. S4 by 16s rDNA sequence analysis.The results from the growth curve showed that these four bacterial isolates unequally grew in DF salts minimal medium with ACC at 0-3% NaCl or pH 7.5-8.5, among of which, Pseudomonas sp. S1 had the highest ACC deaminase activity. The growth of the bacterial isolates was in agreement with their ACC deaminase activity. ACC deaminase activity of the bacterial isolates was inhibited at either 3% NaCl or pH 8.5.The results from either gnotobiotic growth pouch assay or unsterilized soil pot trial showed that these four bacterial isolates unequally enhanced resistance to salt stress in oat(Avena saliva) or annual ryegrass(Lolium multiflorum) seedlings. Among these four bacterial isolates, S1 was the most effective. Compared with control (no NaCl), more plant growth promotion was observed under 10 g/kg NaCl stress. The greatly significant positive correlations between ACC deaminase activity and plant growth parameters tested were observed by Pearson correlation analysis. The results also showed that ACC deaminase, not indole-3-acetic acid (IAA), may be the primary factor for plant growth promotion. Inoculation with either one or two of three PGPR (S1, S3 and Pseudomonas putida UW4) significantly enhanced resistance to salt, drought and flooding stress in Suaeda heteroptera Kitag. Compared with inoculation with two PGPR, inoculation with single PGPR more significantly enhanced Suaeda heteroptera Kitag salt-resistance. But inoculation with S1 showed no significant difference from inoculation with two PGPR on the enhancement of either drought or flooding resistance in Suaeda heteroptera Kitag.Deleterious effects of salt, flooding and petroleum stress on the roots were more than those on the aboveground parts of either oat or annual ryegrass. But inoculation with S1 significantly enhanced plant stress resistance, and greatly enhanced total petroleum hydrocarbons (TPH) removal efficiency from the rhizosphere soils of either oat or annual ryegrass. The results from the stress kinetics showed that change trend of Fv/Fm, the quantum efficiency of open photosystemⅡ, was in agreement with that of aboveground length, which may imply that Fv/Fm may be used as a dynamic diagnostic index for enhancement of stress resistance in plant inoculated with PGPR.更多还原