耐镉根际促生菌的筛选及其对一年生黑麦草镉吸收积累的影响

利用含不同镉(Cd)浓度的LB(Luria-Bertani)培养基,从植物根际土壤分离得到32株耐镉根际菌,测定了这些菌株产吲哚乙酸、ACC脱氨酶活性、溶磷能力并根据培养皿促生试验的复筛结果,选取A02,Oj06和Ps08作为供试菌株。以一年生黑麦草(Lolium multiflorum Lam.)为材料,开展了耐镉根际促生菌调控镉胁迫下幼苗生长的试验。当土壤中镉含量为20±0.33mg·kg-1时,分别接种A02,Oj06和Ps08菌株,结果表明:与未接种菌株相比,接种3种菌株后一年生黑麦草地上部生物量和镉积累量皆显著提高,叶片中膜脂过氧化水平(MDA含量)则显著降低(P0.05),土壤镉有效态含量增加,其中A02处理达显著水平(P0.05)。因此,接种耐镉根际促生菌株可显著促进镉胁迫下一年生黑麦草幼苗生长,并且能通过增加土壤中镉的有效态,促进植株对镉的吸收与积累。

Screening of Cadmium-Tolerant and Plant Growth-Promoting Rhizobacteria and Their Effects on Cadmium Uptake and Accumulation by Lolium multiflorum Lam.

Thirty-two cadmium (Cd)-tolerant and plant growth-promoting rhizobacteria (PGPR) were isolated from the rhizosphere of different plants through adding various concentrations of Cd in the Luria-Bertani media.The characteristics of secreting 3-indoleacetic acid(IAA),ACC deaminase activity and phosphate solubilization ability were determined.And plant growth promoting assay was carried out in petri dish to rescreen all the strains.Three strains (A02,Oj06 and Ps08) were chosen for regulation of Cd-tolerant PGPR on annual ryegrass (Lolium multiflorum Lam.) seedling growth under Cd stress.Pot culture test was carried out when soil contaminated with a Cd concentration of 20±-0.33 mg · kg-1,and the three strains were inoculated in ryegrass.The results showed that the shoot dry weights and Cd accumulation in shoot of ryegrass were significantly increased by inoculation with A02,Oj06 and Ps08,and the peroxide level of leaves (MDA content) decreased significantly(P＜0.05),compared to uninoculated control.Extractable Cd concentration in the rhizosphere increased,especially for the inoculation of A02.Thus,our results indicated that the inoculation with Cd-tolerant PGPR could promote ryegrass seedling growth under Cd stress,and enhance Cd uptake and accumulation by improving available Cd in soil.