钙肥对酸性红壤花生种子萌发及种子际微生物菌群结构的调控

Regulation of peanut seed germination and spermosphere microbial community structure by calcium fertilizer in acidic red soil

红壤因酸度较大且钙素匮乏,严重阻碍种子萌发和植物的形态建成,提高花生出苗、健苗率是酸性红壤花生高效栽培的有效策略之一。钙素营养和种子际土壤微生物对种子萌发均有重要的调控作用,但二者间的内在联系却知之甚少。为揭示钙素营养对花生种子际微生物菌群结构和萌发的潜在影响,以花生品种花育20号(Huayu 20,HY20)为材料,设置不施钙素和外源施钙素盆栽试验,结合菌群高通量测序对花生萌发出苗过程中的种子际微生物菌群结构进行了深度分析。结果表明:各处理种子际样本均以厚壁菌门(Firmicutes)、变形菌门(Proteobacteria)、放线菌门(Actinobacteria)、酸杆菌门(Acidobacteria)、拟杆菌门(Bacteroidetes)为优势细菌门;子囊菌门(Ascomycota)、担子菌门(Basidiomycota)和被孢霉门(Mortierellomycota)为优势真菌门。CaO的施加,使厚壁菌门、拟杆菌门、被孢霉门的相对丰度提高,担子菌门相对丰度降低。另外,钙素营养增加了有益菌芽孢杆菌属(Bacillus)的数量。对细菌功能预测分析结果表明,施用钙素后,与有机物代谢相关的途径(氨基酸转运/代谢、碳水化合物转运等)和抗逆相关的途径(复制重组与修复等)均显著提高,这在一定程度上改善了红壤花生种子的萌发环境。对真菌营养型预测显示,钙素处理提高共生菌群数量的同时,降低了腐生菌群的数量。Redundancy analysis相关性预测分析表明,施钙后土壤细菌和真菌菌群结构与土壤理化因子钙素和pH均呈负相关性,并且土壤钙对种子际土壤微生物的多样性影响大于pH。基于上述研究,酸性红壤施用钙素营养可改善种子际微生物菌群结构,从而促进花生种子萌发。

Acid red soil is characterized by high acid and low calcium,which seriously affects seed germination and plant morphogenesis.Both calcium and spermosphere soil microorganisms play important roles in regulating seed germination,but the mechanisms underlying their relationship are little understood.Improving the emergence and healthy seeding rate of peanut is one of the effective strategies for efficient cultivation of peanut in acidic red soil.To reveal the potential effects of calcium nutrition on the spermosphere microbial community structure and seed germination in peanut,pot experiments were conducted on Huayu 20(HY20)with or without calcium application,and the spermosphere microbial structure during the germination process was analyzed using high-throughput sequencing.The results showed that Firmicutes,Proteobacteria,Actinobacteria,Acidobacteria,and Bacteroidetes were the dominant bacterial phyla,while Ascomycota,Basidiomycota,and Mortierellomycota were the dominant fungal phyla in peanut spermosphere.CaO application increased the relative abundance of Firmicutes,Bacteroidetes,and Mortierellomycota,but decreased the relative abundance of Basidiomycota.In addition,calcium application increased the number of beneficial bacteria Bacillus.Function prediction analysis indicated that the pathways related to organic matter metabolism(amino acid transport,and metabolism,carbohydrate transport,and metabolism)and stress resistance(replication,recombination,and repair)were significantly increased after the application of calcium,which improved the germination environment of peanut seeds in acid red soil to a certain extent.FUNGuild trophic modes analysis revealed that the number of symbiotroph was increased while the number of saprotrophs was decreased after CaO application.Redundancy analysis indicated that the bacterial and fungal structure was negatively correlated with soil physical and chemical factors,calcium content and pH value.Moreover,the calcium content in soil may have a greater regulatory effect on soil microbial diversity than pH.Based on the above studies,the application of calcium in acidic red soil can improve spermosphere microbial structure,resulting in promoting seed germination.