糯高粱叶中IAA产生菌的分离筛选及其促植物生长作用

Isolation and screening of IAA-producing bacteria from glutinous sorghum leaves and its plant growth-promoting function

关键词:  植物内生菌, 分离筛选, 植物生长激素IAA, 种子萌发, 促高粱生长

Key words:  plant endophytic bacteria, isolation and screening, plant growth hormone IAA, seed germination, glutinous sorghum growth promoting

摘要:

糯高粱是白酒酿造的重要原料,其生长过程需要大量的化学肥料,作为环境友好型肥料,微生物菌剂有很广阔的应用前景。为开发对糯高粱生长有促进生长功能的微生物菌剂,该研究以糯高粱叶片为材料,分离筛选具有植物生长激素吲哚乙酸(IAA)产生功能的微生物菌株,基于菌株的16S rDNA保守序列对菌株进行系统发育分析,确定菌株的分类学地位; 通过菌悬液浸种处理,分析菌株对糯高粱种子萌发的影响; 通过盆栽实验,分析菌株对高粱幼苗生长的影响。结果表明:(1)从糯高粱叶片中分离筛选得到4株具有产IAA功能的微生物菌株,分别编号为HY1-1、HY1-2、HY1-3和HY1-4。其中,IAA单位浓度产生量最高的菌株是HY1-1,为2.56 mol·L^-1。(2)运用贝叶斯推断树对菌株16S rDNA进行系统发育分析,结果显示这4株菌都属于枯草芽孢杆菌(Bacillus subtilis)。(3)HY1-1、HY1-2、HY1-3和HY1-4都能促进糯高粱种子萌发,与对照组相比,经菌悬液浸泡的糯高粱种子发芽率显著提高了40.04%～165.52%,其中促进效果最明显的是HY1-1,种子发芽率提高了165.52%。(4)选取HY1-1菌株做盆栽实验,在糯高粱幼苗根部接种HY1-1 30 d后,糯高粱幼苗的株高显著增加了29.17%、全磷含量显著增加了5.12%; 糯高粱根际基质中速效氮显著增加了31.70%,有效磷显著增加了28.88%。综上认为,糯高粱叶内生菌HY1-1能够通过分泌植物生长激素IAA以及为植物提供营养元素等方式促进糯高粱植株的生长。该研究结果为进一步开发促糯高粱生长菌剂提供了种质资源。

Abstract:

Glutinous sorghum is an important raw material for the production of Baijiu(Chinese liquor). During its growth process, glutinous sorghum requires a substantial amount of chemical fertilizers. As an environmentally friendly fertilizer, microbial agent has a great application prospect in future. The aim of this paper was to develop a growth promoting microbial agent for glutinous sorghum. In this study, the glutinous sorghum leaves were used as experimental materials to isolate and screen microbial strains with plant growth hormone indole acetic acid(IAA)production ability. Phylogenetic analysis was performed to determine the taxonomic status of these microbial strains based on the 16S rDNA conserved sequences. The effects of strains on glutinous sorghum seed germination were analyzed by soaking the seeds with bacterial suspension. The effects of strains on the sorghum seedlings growth were analyzed by pot experiment. The results were as follows:(1)Four microbial strains capable of producing IAA were isolated and screened from glutinous sorghum leaves, designated as HY1-1, HY1-2, HY1-3, and HY1-4. Among them, HY1-1 exhibited the highest IAA production per unit concentration which was 2.56 mol·L^-1.(2)Bayesian inference tree analysis based on the 16S rDNA sequences revealed that all four strains belonged to Bacillus subtilis.(3)HY1-1, HY1-2, HY1-3, and HY1-4 could promote the glutinous sorghum seed germination rates. Compared to the control groups, the germination rates of glutinous sorghum seeds soaked in bacterial suspension significantly increased by 40.04% to 165.52%. Among them, HY1-1 demonstrated the most prominent promotion effect, with a germination rate increase of 165.52%.(4)HY1-1 strain was selected for a pot experiment. After 30 days of inoculation on the roots of glutinous sorghum seedlings, the plant heights of the seedlings significantly increased by 29.17%, and total phosphorus content increased significantly by 5.12%. The rhizosphere substrate of glutinous sorghum exhibited a significant increase in available nitrogen content by 31.70% and available phosphorus content by 28.88%. In conclusion, HY1-1, an endophytic bacterium in glutinous sorghum leaves, can promote the growth of glutinous sorghum plants by secreting the plant growth hormone IAA and providing necessary nutrients. This study provides genetic resources for the further development of microbial agent targeting the growth promotion of glutinous sorghum.