陕北风沙草滩区覆膜对玉米根际土壤微生物群落的影响
Effects of Film Mulching on Rhizosphere Soil Microbial Community of Maize in Wind-Sand Grassy Beach Area of Northern Shaanxi Province
通讯作者:
收稿日期: 2023-02-20 修回日期: 2023-05-6 网络出版日期: 2023-09-13
基金资助: |
|
Received: 2023-02-20 Revised: 2023-05-6 Online: 2023-09-13
作者简介 About authors
李佳奇,研究方向为马铃薯及饲用作物遗传育种,E-mail:
为明确不同覆膜条件下玉米根际土壤微生物群落结构变化,收集6份不同覆膜条件下的玉米根际土壤,利用高通量测序技术对其微生物样品的基因区进行测序,分析样本中根际土壤细菌和真菌群落结构特征,揭示覆膜对玉米根际土壤质量的影响。结果表明,覆膜条件下样品细菌和真菌的总OTU(分类操作单元)数高于未覆膜条件。Chaol和Shannon指数表明,覆膜下细菌和真菌群落的丰富度和多样性均高于未覆膜处理。从门水平上来看,农田覆膜可降低变形菌门(Proteobacteria)和拟杆菌门(Bacteroidota)的相对丰度,提高酸杆菌门(Acidobacteriota)、芽单胞菌门(Gemmatimonadota)、子囊菌门(Ascomycota)和球囊菌门(Glomeromycota)的相对丰度;从属水平上来看,农田覆膜使玉米根际土壤富集了细菌中的MND1、嗜盐粘细菌(Haliangium)、杆菌属(Metagenome)、RB41、鞘脂单胞菌属(Sphingomonas)和真菌中的外瓶霉属(Exophiala)、绿僵菌属(Metarhizium)、球孢毛葡孢霉属(Botryotrichum)、锥毛壳属(Coniochaeta)、瓶毛壳属(Lophotrichus)、镰刀菌属(Fusarium)等菌群。研究揭示了农田覆膜对玉米根际土壤生态效应的影响,为筛选和开发利用有益微生物提供依据。
关键词:
In order to clarify the changes of microbial community structure in maize rhizosphere soil under different mulching conditions, six samples of maize rhizosphere soil under different mulching conditions were collected. High-throughput sequencing technology was used to sequence the gene regions of microbial samples of maize rhizosphere soil, so as to analyze the community structure characteristics of bacteria and fungi in the sample rhizosphere soil, and reveal the influence of mulching soil on the quality of maize rhizosphere soil. The results showed that the total OTU number of bacteria and fungi in the field covered with mulch were higher than that in the field without mulching. Chaol and Shannon indexes revealed that the richness and diversity of fungi and bacteria community in the rhizosphere soil of maize under mulching were higher than those without mulching. At the phylum level, the relative abundance of Proteobacteria and Bacteroidota were decreased and that of Acidobacteria, Gemmatimonadota, Ascomycota and Glomeromycota were increased. At the genus level, film mulching caused the enrichment of MND1, Haliangium, Metagenome, RB41, Sphingomonas in bacteria and Exophiala, Metarhizium, Botryotrichum, Coniochaeta, Lophotrichus, Fusarium in fungi in the rhizosphere soil of maize. This study presented the scientific theoretical foundation for the selection, use, and exploitation of beneficial microorganisms in maize production. It also demonstrated the impact of agricultural mulching on the ecological effect of maize rhizosphere soil.
Keywords:
本文引用格式
李佳奇, 史建国, 陈启航, 常风云, 段义忠, 柴乖强, 贾磊, 陈涛.
Li Jiaqi, Shi Jianguo, Chen Qihang, Chang Fengyun, Duan Yizhong, Chai Guaiqiang, Jia Lei, Chen Tao.
玉米(Zea mays L.)是禾本科玉米属植物,是继水稻、小麦之后的世界第三大粮食作物,也是我国重要的粮、饲和工业原料,对促进国家经济发展和保障粮食安全有重要作用。玉米具有产量高、抗性优和适应性广等优良特性,广泛种植于我国多个地区[1⇓-3]。陕北风沙草滩区是塞北高原的“陕西第二粮仓”,也是我国生态环境极其脆弱的地区之一,低温干旱和水资源短缺等环境因素极大限制了该区域玉米的生产发展。而地膜覆盖可高效增温、保墒保肥和防除杂草等,是实现玉米稳产高产的重要种植技术之一[4]。目前,已有研究[5⇓-7]从作物的生长、土壤水分运输、土壤温度和土壤养分利用等方面阐述了覆膜对玉米生产的影响机制,但关于覆膜条件下玉米根际土壤微生物多样性及群落结构特征变化的研究相对较少。
植物根际土壤是由根系周围且受其影响、富含营养的区域土壤构成,是复杂的生态系统,分布有真菌、细菌、线虫和原生生物等[8-9]。根际土壤微生物与植物生长发育、抗性、繁殖力和生产力等密切相关。Shimurah等[10]以大花杓兰幼苗、成株及原球茎为研究材料,分离其瘤菌根(Epulorhiza)真菌进行促萌发试验,发现来自成株的菌根真菌具有较高的促萌发率。Takakura[11]研究发现,外生菌根真菌Tricholoma matsutake能通过其子实体产生过氧化氢,抑制植物病原真菌(Rhizoctohia solahi)的生长。Shaikh等[12]研究发现,不同根际真菌可提高薄荷油料产量和薄荷脑含量,并证明绿色木霉(T.viride)可有效提高油分和薄荷醇含量。环境因素和人为措施会影响根际土壤微生物活性,地膜覆盖因改变了土壤温度、水分和湿度等,进而对土壤微生物群落结构产生影响。Dong等[13]研究表明,地膜覆盖可显著增加土壤微生物多样性和丰富度。Wang等[14]研究发现,农田土壤覆膜后,加剧了土壤中微生物群落的演替,影响其结构的稳定性和多样性。因此,探讨不同覆膜条件下玉米根际土壤真菌和细菌群落结构的变化,评估农田覆膜对玉米根际土壤生态效应的影响,对促进陕北风沙草滩区旱作玉米高产稳产具有重要意义。
1 材料与方法
1.1 试验材料与试验地概况
本研究以玉米品种中榆968为供试材料,该品种产量高,抗旱性、抗病性及适应性强。材料种植于陕西省榆林市榆阳区农牧基地,该区属典型黄土高原沟壑区,是主要旱作农业区,土壤的质地以砂壤土为主,pH 8.0,土壤含有机质3.46 g/kg、铵态氮5.6 mg/kg、硝态氮2.0 mg/kg。采用宽窄行种植,宽行80 cm,窄行40 cm,播种深度4~5 cm,种植密度为75 000株/hm2,试验设地膜覆盖(M)和不覆盖(T)2个处理,各3次重复,其中M处理于播种前将可降解地膜覆盖于地表,生长期间根据植株生长情况适量施肥(磷酸二铵和尿素各300 kg/hm2)和灌溉,防除杂草,确保植株正常生长。
1.2 样品采集
于玉米收获后铲除玉米根系周围落叶层,用土壤刀从玉米基部开始逐段逐层挖去上层覆土,沿侧根找到须根部分,采集20 cm深的分枝部分,轻轻抖掉非根际土,用毛刷收集仍粘在根上的根际土,去除植物根、动物残骸以及其他杂质后分装到3个无菌离心管里。分别采集覆膜与未覆膜处理下的玉米根际土壤,每个处理选择3株植株,每个处理土样总采样量约为20 g,混匀后,封入灭菌的20 mL离心管,每管5 g,密封后分别标号(M1、M2、M3及T1、T2、T3)并立即储存于-80 ℃条件,用干冰运输送样本。
1.3 根际土壤基因组DNA的提取
利用土壤DNA提取试剂盒[天根生化科技(北京)有限公司]进行DNA提取,使用Nanodrop 2000紫外可见分光光度计(Nanodrop,Wilmington,DE,美国)对土壤DNA进行定量,用1%琼脂糖凝胶电泳检测其完整性,质量合格的DNA样品委托北京奥维森基因科技有限公司进行高通量测序。
1.4 PCR扩增及测序
使用细菌通用引物515F(5′-GTGCCAGCM GCCGCGGTAA-3′)和806R(5′-GGACTACHVGG GTWTCTAAT-3′)对样品细菌16S rRNA基因V4区域进行扩增。采用真菌通用引物ITSF(5′-CTT GGTCATTTAGAGGAAGTAA-3′)和ITSR(5′-GCT GCGTTCTTCATCGATGC-3′)对样品真菌ITS1区域进行扩增。将获得的PCR产物通过1%琼脂糖凝胶电泳定量,用核酸纯化试剂盒Agencourt AMPure XP纯化,均一化形成测序文库,文库质检合格后于Illumina HiSeq 2500平台测序。
1.5 数据处理
1.5.1 测序数据
测序后得到原始数据文件,经碱基识别(base calling)分析转化为原始序列(raw reads),利用Trimmomatic软件(V0.36)对序列数据初步质控,采用Flash软件(V1.2.0)拼接处理两端序列,利用Uchime软件(V4.2)去除嵌合体序列,得到有效序列(clean reads)。
1.5.2 OTU聚类分析
为了便于了解样品测序结果中菌种、菌属等数目信息,采用QIIME软件(V1.8.0)将具有相似性的有效序列聚类分组,一个小组是一个分类操作单元(operational taxonomic unit,OTU),对97%相似度条件下的OTU进行生物信息统计分析并制作稀释性曲线。基于Silva数据库(
1.5.3 微生物多样性及群落结构分析
利用QIIME软件(V1.8.0)计算Alpha多样性指数(包括Chao1、ACE、Shannon和Simpson指数)。在不同水平下统计各样品的群落结构组成。通过QIIME软件得到各样品的物种丰度表,并利用R软件绘制群落结构图。
2 结果与分析
2.1 样品测序质量分析
对不同覆膜条件下玉米根际土壤6组真菌样品进行高通量测序,共获得1 879 225对原始序列,去除嵌合体和短序列后获得1 805 884对优质序列(clean tags),其中覆膜条件下玉米根际土壤样品共产生990 897对优质序列,未覆膜条件下玉米根际土壤样品共产生814 987对优质序列,各样品平均获得300 981对优质序列。对不同的优质序列进行聚类降噪(相似度水平≥97%),共获得3052个OTU,覆膜和未覆膜玉米根际土壤真菌OTU分别为2632和2416。绘制稀释性曲线用于验证样品测序数据量不同时物种的丰富度,如图1a所示,测序数据达50 000时,6组样本的曲线趋于平坦,表明样本测序数据量合理,不会随测序数据量的增多产生较多新的OTU,说明试验准确可靠。
图1
图1
真菌(a)和细菌(b)样品稀释性曲线图
Fig.1
Rarefaction curves of the fungal (a) and bacteria (b) samples
对不同覆膜条件下玉米根际土壤6组细菌样品进行高通量测序,共获得1.8 937对原始序列,去除嵌合体和短序列后获得优质序列1.2 161对,其中覆膜条件下共产生578 873对,未覆膜条件下共产生593 288对,各样品平均获得195 360对优质序列。对不同的优质序列进行聚类降噪(相似性度水平≥97%),共获得9456个OTU,覆膜和未覆膜处理玉米根际土壤细菌OTU分别为8757和8789。绘制稀释性曲线用于验证样品测序数据量不同时物种的丰富度,如图1b,测序数据达50 000时,6组样本的曲线趋于平坦,表明样本测序数据量合理,能准确可靠地反映不同覆膜条件下玉米根际土壤微生物群落结构特征。
2.2 玉米根际土壤真菌和细菌OTU分析
不同覆膜条件下玉米根际土壤样品通过聚类降噪共获得3052个真菌OTU,其中各样品间OTU数不尽相同,如图2a所示,M2的OTU数量最多,为1883,T2的OTU数量最少,仅1611。综合分析,覆膜条件下玉米根际土壤OTU数量高于未覆膜条件下,表明覆膜可提高玉米根际土壤真菌的OTU数量。不同覆膜条件下6组样品通过聚类降噪共获得9456个细菌OTU,其中各样品间的OTU数不尽相同,如图2b所示,M2的OTU数目最多,为7110,T1样品获得6943个OTU,为倒数第二,M1样品的OTU数量最少,为6926。整体来看,覆膜条件下样品细菌的总OTU数量高于未覆膜条件。此外,覆膜条件下玉米根际土壤细菌OTU数量显著高于真菌OTU数量,表明覆膜有利于玉米根际土壤细菌OTU增多。
图2
图2
真菌(a)和细菌(b)样品的OTU数量
Fig.2
The number of OTUs in fungal (a) and bacteria (b) samples
图3
图4
图4
玉米根际土壤细菌OTU-Venn图
Fig.4
OTU-Venn graph of rhizosphere soil bacteria in maize
2.3 不同覆膜条件下玉米根际土壤真菌和细菌的多样性分析
由表1可知,不同覆膜条件下,各样本根际土壤微生物观测深度均≥99%,表明本次测序结果能科学可靠地代表样本中微生物的真实情况。不同覆膜条件下,各样品系谱多样性指数细菌最高为429.44,而真菌最高为290.15,表明玉米根际土壤细菌群落的多样性较高。Chao1指数可反映样品微生物群落丰富度且两者呈正相关,总体来看,各样品细菌Chao1指数明显高于真菌,在覆膜条件下,样品真菌的Chao1指数明显高于未覆膜条件,而覆膜处理下样品细菌的Chao1彼此间差异不明显,表明玉米根际土壤细菌群落中物种丰富度较真菌群落更高,通过覆膜处理可增加各样品微生物群落丰富度,尤其可提高玉米根际土壤真菌群落中物种的丰富度。Shannon指数和Simpson指数用来衡量微生物的多样性,在覆膜处理下,大部分样品真菌和细菌的Shannon指数均高于未覆膜,而Simpson指数在不同处理下差异较小,表明覆膜处理可提高玉米根际土壤真菌和细菌群落的多样性。结合上述指标,发现覆膜处理可改善玉米根际土壤微生物群落丰富度和多样性,其中真菌群落的变化最明显。
表1 各样品根际土壤真菌和细菌多样性指数
Table 1
项目 Item | 处理 Treatment | 样品 Sample | Chao1指数 Chao1 index | 观测深度 Observation depth | 观测OTU数 Observed OTU species | 系谱多样指数 PD whole tree | Shannon指数 Shannon index | Simpson指数 Simpson index |
---|---|---|---|---|---|---|---|---|
真菌Fungus | M | M1 | 2287.73 | 1.00 | 1719.90 | 267.19 | 5.88 | 0.94 |
M2 | 2452.34 | 1.00 | 1883.00 | 290.15 | 6.18 | 0.95 | ||
M3 | 2365.02 | 1.00 | 1824.00 | 282.20 | 6.16 | 0.94 | ||
T | T1 | 2227.37 | 1.00 | 1739.00 | 278.99 | 6.10 | 0.95 | |
T2 | 2190.50 | 1.00 | 1611.00 | 261.28 | 5.83 | 0.95 | ||
T3 | 2253.29 | 1.00 | 1615.00 | 252.55 | 5.78 | 0.94 | ||
细菌Bacteria | M | M1 | 8258.27 | 0.99 | 6926.00 | 420.85 | 10.71 | 1.00 |
M2 | 8434.04 | 0.99 | 7110.00 | 429.44 | 10.73 | 1.00 | ||
M3 | 8314.83 | 0.99 | 7038.00 | 429.44 | 10.72 | 1.00 | ||
T | T1 | 8352.32 | 0.99 | 6942.00 | 425.28 | 10.54 | 1.00 | |
T2 | 8420.07 | 0.99 | 7008.00 | 423.80 | 10.68 | 1.00 | ||
T3 | 8330.19 | 0.99 | 7066.00 | 426.08 | 10.72 | 1.00 |
2.4 不同处理下玉米根际土壤真菌和细菌的群落结构
2.4.1 门水平的菌群结构分析
在不同处理下,玉米根际土壤细菌门水平群落相对丰度见图5,其相对丰度由高到低为变形菌门(Proteobacteria)、酸杆菌门(Acidobacteriota)、放线菌门(Actinobacteriota)、芽单胞菌门(Gemmatimonadota)、拟杆菌门(Bacteroidota)、绿弯菌门(Chloroflexi)、粘菌门(Myxococcota)、浮霉菌门(Planctomycetota)、疣微菌门(Verrucomicrobiota)、迟杆菌门(Latescibacterota)、泉古菌门(Crenarchaeota)和厚壁菌门(Firmicutes)等。如表2所示,不同覆膜条件下玉米根际土壤中变形菌门和拟杆菌门在其细菌组成结构中占比分别为33.94%和7.43%,低于未覆膜条件下其在细菌组成结构中的占比(36.17%和8.46%)。而覆膜处理下酸杆菌门和芽单胞菌门在细菌组成结构中占比分别为11.03%和9.54%,均高于未覆膜处理(9.62%和8.30%)。由此可知,土地覆膜可改变玉米根际土壤细菌组成结构。
图5
图5
不同样本的细菌门分类水平群落相对丰度
Fig.5
Relative abundance of different samples of bacteria at the phylum level
表2 不同覆膜条件下各样品细菌在门分类水平的占比
Table 2
处理 Treatment | 样品 Sample | 变形菌门 Proteobacteria | 酸杆菌门 Acidobacteriota | 放线菌门 Actinobacteriota | 芽单胞菌门 Gemmatimonadota | 拟杆菌门 Bacteroidota | 绿弯菌门 Chloroflexi | 粘菌门 Myxococcota | 浮霉菌门 Planctomycetota | 其他 Others |
---|---|---|---|---|---|---|---|---|---|---|
M | M1 | 33.71 | 10.44 | 10.26 | 10.30 | 8.37 | 5.71 | 5.33 | 4.35 | 8.08 |
M2 | 33.38 | 12.09 | 8.25 | 10.50 | 6.89 | 6.16 | 5.62 | 5.23 | 8.38 | |
M3 | 34.72 | 10.57 | 10.96 | 7.82 | 7.02 | 7.28 | 5.01 | 5.15 | 8.36 | |
均值 | 33.94 | 11.03 | 9.82 | 9.54 | 7.43 | 6.38 | 5.32 | 4.91 | 8.27 | |
T | T1 | 37.23 | 10.13 | 5.92 | 9.13 | 11.59 | 4.91 | 5.12 | 4.10 | 7.38 |
T2 | 37.37 | 8.30 | 12.02 | 8.28 | 7.55 | 6.77 | 4.76 | 3.75 | 8.46 | |
T3 | 33.93 | 10.43 | 11.71 | 7.49 | 6.25 | 8.92 | 4.07 | 5.36 | 8.82 | |
均值 | 36.17 | 9.62 | 9.88 | 8.30 | 8.46 | 6.87 | 4.65 | 4.40 | 8.22 |
图6
图6
不同样本的真菌门分类水平群落相对丰度
Fig.6
Relative abundance of different samples of fungus at the phylum level
表3 不同覆膜条件下各样品真菌在门分类水平的占比
Table 3
处理 Treatment | 样品 Sample | 子囊菌门 Ascomycota | 未确定 Unidentified | 担子菌门 Basidiomycota | 被孢菌门 Mortierellomycota | 球囊菌门 Glomeromycota | 其他 Others |
---|---|---|---|---|---|---|---|
M | M1 | 78.16 | 10.57 | 4.04 | 4.34 | 2.10 | 0.79 |
M2 | 65.22 | 10.14 | 18.47 | 3.24 | 1.90 | 1.04 | |
M3 | 75.12 | 10.94 | 6.04 | 4.25 | 2.28 | 1.37 | |
均值 | 72.83 | 10.55 | 9.51 | 3.94 | 2.09 | 1.07 | |
T | T1 | 65.82 | 13.63 | 13.44 | 4.01 | 1.71 | 1.40 |
T2 | 66.68 | 17.82 | 8.00 | 4.36 | 1.75 | 1.39 | |
T3 | 69.21 | 16.79 | 6.84 | 3.54 | 2.05 | 1.58 | |
均值 | 67.24 | 16.08 | 9.43 | 3.97 | 1.83 | 1.46 |
2.4.2 属水平的菌群结构分析
图7
图7
不同样本的细菌属分类水平群落相对丰度
Fig.7
Relative abundance of different samples of bacteria at the genus level
表4 不同覆膜条件下各样品细菌在属分类水平的占比
Table 4
处理 Treatment | 样品 Sample | 未确定 Unidentified | 未分类 Unclassified | 未培养菌 Uncultured-bacterium | MND1 | 嗜盐粘细菌 Haliangium | 杆菌属 Metagenome | RB41 | 溶杆菌属 Lysobacter | 鞘脂单胞菌属 Sphingomonas | 其他 Others |
---|---|---|---|---|---|---|---|---|---|---|---|
M | M1 | 23.37 | 18.90 | 11.07 | 2.20 | 1.57 | 1.53 | 1.31 | 0.84 | 1.06 | 38.15 |
M2 | 25.68 | 18.13 | 10.62 | 2.28 | 1.82 | 1.69 | 1.79 | 0.78 | 1.09 | 36.14 | |
M3 | 22.13 | 18.22 | 10.84 | 1.73 | 1.46 | 1.46 | 1.29 | 0.84 | 1.10 | 40.95 | |
均值 | 23.72 | 18.42 | 10.84 | 2.07 | 1.61 | 1.56 | 1.46 | 0.82 | 1.08 | 38.41 | |
T | T1 | 21.99 | 19.00 | 9.52 | 2.15 | 1.72 | 1.55 | 1.74 | 1.77 | 0.98 | 39.58 |
T2 | 21.43 | 18.69 | 10.15 | 1.95 | 1.42 | 1.24 | 0.87 | 1.24 | 0.93 | 42.08 | |
T3 | 21.62 | 18.59 | 11.01 | 1.79 | 1.32 | 1.25 | 1.18 | 1.02 | 0.94 | 41.30 | |
均值 | 21.68 | 18.76 | 10.23 | 1.96 | 1.49 | 1.34 | 1.26 | 1.34 | 0.95 | 40.98 |
在不同覆膜条件下玉米根际土壤真菌属水平群落相对丰度见图8,有命名信息的玉米根际土壤真菌优势菌属有外瓶霉属(Exophiala)、绿僵菌属(Metarhizium)、帚枝霉属(Sarocladium)、球孢毛葡孢霉属(Botryotrichum)、锥毛壳属(Coniochaeta)、瓶毛壳属(Lophotrichus)、镰刀菌属(Fusarium)等。如表5所示,未确定和其他菌属在各样品中占比较大,覆膜条件下玉米根际土壤的外瓶霉属、绿僵菌属、球孢毛葡孢霉属、锥毛壳属、瓶毛壳属和镰刀菌属在真菌结构中占比分别为12.47%、16.69%、5.85%、6.22%、4.23%和2.47%,高于未覆膜处理。而帚枝霉属在覆膜条件占比远低于未覆膜处理,由此可见,土地覆膜可改变玉米根际土壤真菌组成结构。
图8
图8
不同样本的真菌属分类水平群落相对丰度
Fig.8
Relative abundance of different samples of fungi at the genus level
表5 不同覆膜条件下各样品真菌在属分类水平的占比
Table 5
处理 Treatment | 样品 Sample | 未确定 Unidentified | 外瓶霉属 Exophiala | 绿僵菌属 Metarhizium | 帚枝霉属 Sarocladium | 球孢毛葡孢霉属 Botryotrichum | 锥毛壳属 Coniochaeta | 瓶毛壳属 Lophotrichus | 镰刀菌属 Fusarium | 其他 Others |
---|---|---|---|---|---|---|---|---|---|---|
M | M1 | 28.18 | 9.90 | 16.97 | 2.66 | 5.94 | 13.13 | 5.01 | 2.44 | 15.78 |
M2 | 36.62 | 10.83 | 15.48 | 2.92 | 6.18 | 3.38 | 2.73 | 2.97 | 18.88 | |
M3 | 25.80 | 16.68 | 17.62 | 5.20 | 5.44 | 2.16 | 4.94 | 1.98 | 20.18 | |
均值 | 30.20 | 12.47 | 16.69 | 3.59 | 5.85 | 6.22 | 4.23 | 2.47 | 18.28 | |
T | T1 | 52.73 | 6.40 | 1.49 | 15.03 | 1.36 | 0.32 | 1.56 | 1.67 | 19.43 |
T2 | 46.16 | 10.17 | 5.04 | 14.96 | 1.58 | 0.28 | 2.37 | 1.75 | 17.68 | |
T3 | 44.55 | 11.49 | 3.68 | 15.80 | 1.92 | 0.26 | 2.40 | 1.44 | 18.45 | |
均值 | 47.82 | 9.36 | 3.40 | 15.26 | 1.62 | 0.29 | 2.11 | 1.62 | 18.52 |
3 讨论
微生物是土壤中营养物质转化和循环的驱动力,其含量可随土壤环境发生变化,是评价土壤质量的关键指标[21]。随着科学技术不断发展,覆膜技术在经济作物栽培中已不可或缺。相关研究[22]表明,地膜覆盖可改变土壤理化性质,使微生物养分供需发生变化,造成其生长和活性改变,进而导致植物根际土壤的微生物群落结构和多样性发生变化。宋秋华[23]通过研究黄绵土区不同覆膜时期对旱作麦田土壤微生物数量的影响发现,与裸地相比,覆膜处理下微生物数量提高1.17~3.82倍。段翠花[24]以不同类型的地膜为覆盖材料,无任何作物条件下,分析了地膜覆盖对土壤细菌群落等的影响,发现普通膜覆盖相较于无覆膜处理改变了土壤细菌群落组成,此外,生物降解膜较无覆膜处理提高了土壤细菌的OTU。丁柳屹等[25]通过分析黄土高原旱作玉米农田无覆盖和地膜覆盖等不同处理下土壤细菌群落组成发现,地膜覆盖显著增加了玉米农田土壤细菌的丰富度,但降低了细菌多样性。Huang等[26]研究发现,农田覆盖显著影响了土壤真菌群落的组成,子囊菌门(Ascomycetes)和核菌(Sordariomycetes)是不同处理中最主要的门类。胡志娥等[27]对不同覆膜年限的农田土壤微生物群落进行研究,发现短期覆膜条件下的农田土壤中真菌群落结构多样性显著增加。徐雪雪[28]研究发现,农田覆膜可显著提高土壤真菌Shannon指数、丰富度和均匀度。上述研究表明,覆膜处理可改善土壤微生物群落结构特征,降低土壤细菌群落多样性,显著增加土壤真菌群落的丰富度和多样性。本试验对不同处理下的玉米根际土壤微生物群落进行测序,结果表明覆膜处理可改善玉米根际土壤微生物群落丰富度和多样性,其中真菌群落的丰富度和多样性显著提高。研究结果与上述研究一致,原因可能是地膜覆盖使玉米根际土壤发生酸化,抑制了土壤细菌群落的活性,导致其群落多样性降低。同时,玉米根际土壤理化性质的改变,如土壤团聚体的形成,增加了土壤通气性,有利于真菌的繁殖与生长,进而导致覆膜条件下土壤真菌的丰富度提高。
植物根与其根际微生物群间的相互作用对植物生长发育至关重要[29]。Voges等[30]研究表明,在拟南芥缺铁情况下,植物来源的香豆素有助于重塑其特定的微生物群落成,改善植株的铁营养状况。Cotton等[31]通过试验证明,苯并噁唑嗪酮类化合物等特定次生代谢物可使玉米根际微生物群落特异性发生变化。因此,宿主根的特定代谢物组成可显著影响根际微生物群落的分类和富集。Yu等[32]对玉米根提取物和渗出液中的靶向代谢物进行分析,发现黄酮生物合成和分泌可触发宿主根和根际微生物间的相互作用,造成玉米根际中细菌类群草酸杆菌科的富集,从而促进玉米在氮匮乏土壤中的生长和对氮的获取。上述研究表明,环境及植物根的分泌物对根际微生物群落具有一定影响,植物能够通过改变其根际微生物群落类型来适应环境。本试验对不同覆膜条件下的玉米根际土壤微生物群落进行测序分析,发现农田覆膜提高了酸杆菌门等相对丰度,可能是农田覆膜改变了玉米根际微环境,促使玉米根际分泌某种次生代谢物重塑特定的微生物群落来适应环境。
不同根际土壤微生物群落对地膜覆盖的响应不尽相同。本研究发现,从门水平上来看,农田覆膜可改变玉米根际土壤微生物优势菌群的组成,如降低变形菌门和拟杆菌门相对丰度,提高酸杆菌门、芽单胞菌门、子囊菌门和球囊菌门相对丰度。李越鲲等[33]对枸杞、付亚娟等[34]对大花灼兰、黄方园[35]对玉米根际土壤微生物优势菌群的研究也得到相似结果。推测可能是子囊菌无性繁殖能力很强,覆膜条件下利于产生大量分生孢子,快速增长,提高其群体相对丰度。而对于覆膜条件下变形菌门丰度的提高及酸杆菌门丰度降低等现象,Fan等[36]研究发现,该类菌在营养物质富足尤其是碳富余的环境中生长旺盛。而在低有机碳环境下,酸杆菌在土壤中的相对丰度较高[37]。因此,原因可能是覆膜使根际土壤的有机碳含量减少,导致变形菌门丰度降低而酸杆菌门丰度提升。此外,本研究发现,在不同覆膜条件下玉米根际土壤微生物类群中,未分类真菌和细菌占比较大,表明根际土壤微生物种类繁多,存在大量新类群,有待深入发掘解析。
4 结论
通过高通量测序技术分析不同覆膜处理下玉米根际土壤微生物的群落结构特征,发现农田覆膜可改善玉米根际土壤微生物群落丰富度和多样性,其中真菌群落的丰富度和多样性显著提高。从门水平上来看,农田覆膜可降低变形菌门和拟杆菌门相对丰度,提高酸杆菌门、芽单胞菌门、子囊菌门和球囊菌门的相对丰度。从属水平上来看,农田覆膜使玉米根际土壤富集细菌中的MND1、嗜盐粘细菌、杆菌属、RB41、鞘脂单胞菌属和真菌中的外瓶霉属、绿僵菌属、球孢毛葡孢霉属、锥毛壳属、瓶毛壳属、镰刀菌属等菌群。
参考文献
Genome-wide association study uncovers new genetic loci and candidate genes underlying seed chilling-germination in maize
Effect of irrigation and fertilization regimes on grain yield, water and nitrogen productivity of mulching cultivated maize (Zea mays L.) in the Hetao Irrigation District of China
Effect of film mulching and microbial inoculation on maize growth and water use efficiency under drought stress
Exercising influence: distinct biotic interactions shape root microbiomes
The rhizosphere microbiota of plant invaders: an overview of recent advances in the microbiomics of invasive plants
Characterization of mycorrhizal fungi isolated from the threatened cypripedium macranthos, in a northern island of Japan: two phylogenetically distinct fungi associated with the orchid
DOI:10.1007/s00572-009-0251-4
PMID:19449040
[本文引用: 1]
We isolated Rhizoctonia-like fungi from populations of the threatened orchid Cypripedium macranthos. In ultrastructural observations of the septa, the isolates had a flattened imperforate parenthesome consisting of two electron-dense membranes bordered by an internal electron-lucent zone, identical to the septal ultrastructure of Rhizoctonia repens (teleomorph Tulasnella), a mycorrhizal fungus of many orchid species. However, hyphae of the isolates did not fuse with those of known tester strains of R. repens and grew less than half as fast as those of R. repens. In phylogenetic analyses, sequences for rDNA and internal transcribed spacer (ITS) regions of the isolates were distinct from those of the taxonomically identified species of Tulasnella. On the basis of the ITS sequences, the isolates clustered into two groups that corresponded exactly with the clades demonstrated for other Cypripedium spp. from Eurasia and North America despite the geographical separation, suggesting high specificity in the Cypripedium-fungus association. In addition, the two phylogenetic groups corresponded to two different plant clones at different developmental stages. The fungi from one clone constituted one group and did not belong to the other fungal group isolated from the other clone. The possibility of switching to a new mycorrhizal partner during the orchid's lifetime is discussed.
Tricholoma matsutake fruit bodies secrete hydrogen peroxide as a potent inhibitor of fungal growth
Influence of rhizosphere fungi on essential oil production and menthol content in Mentha arvensis L.
Influence of film mulching on soil microbial community in a rainfed region of northeastern China
DOI:10.1038/s41598-017-08575-w
PMID:28814759
[本文引用: 1]
Information about the effect of plastic film mulching (PFM) on the soil microbial communities of rainfed regions remains scarce. In the present study, Illumina Hiseq sequencer was employed to compare the soil bacterial and fungal communities under three treatments: no mulching (NM), spring mulching (SM) and autumn mulching (AM) in two layers (0-10 and, 10-20 cm). Our results demonstrated that the plastic film mulching (PFM) application had positive effects on soil physicochemical properties as compared to no-mulching (NM): higher soil temperature (ST), greater soil moisture content (SMC) and better soil nutrients. Moreover, mulching application (especially AM) caused a significant increase of bacterial and fungal richness and diversity and played important roles in shaping microbial community composition. These effects were mainly explained by the ST and SMC induced by the PFM application. The positive effects of AM and SM on species abundances were very similar, while the AM harbored relatively more beneficial microbial taxa than the SM, e.g., taxa related to higher degrading capacity and nutrient cycling. According to the overall effects of AM application on ST, SMC, soil nutrients and microbial diversity, AM is recommended during maize cultivation in rain-fed region of northeast China.
LDPE microplastics significantly alter the temporal turnover of soil microbial communities
Diversity and heritability of the maize rhizosphere microbiome under field conditions
Structure, variation, and assembly of the root-associated microbiomes of rice
Legacy of land use history determines reprogramming of plant physiology by soil microbiome
Arbuscular mycorrhizal fungi increase organic carbon decomposition under elevated CO2
DOI:10.1126/science.1224304
PMID:22936776
[本文引用: 1]
The extent to which terrestrial ecosystems can sequester carbon to mitigate climate change is a matter of debate. The stimulation of arbuscular mycorrhizal fungi (AMF) by elevated atmospheric carbon dioxide (CO(2)) has been assumed to be a major mechanism facilitating soil carbon sequestration by increasing carbon inputs to soil and by protecting organic carbon from decomposition via aggregation. We present evidence from four independent microcosm and field experiments demonstrating that CO(2) enhancement of AMF results in considerable soil carbon losses. Our findings challenge the assumption that AMF protect against degradation of organic carbon in soil and raise questions about the current prediction of terrestrial ecosystem carbon balance under future climate-change scenarios.
Fertilization practices alter microbial nutrient limitations after alleviation of carbon limitation in a Ferric Acrisol
Effects of different long-term farmland mulching patterns on the loessial soil fungal community in a semiarid region of China
Root type and soil phosphate determine the taxonomic landscape of colonizing fungi and the transcriptome of field-grown maize roots
Plant-derived coumarins shape the composition of an Arabidopsis synthetic root microbiome
Metabolic regulation of the maize rhizobiome by benzoxazinoids
Plant flavones enrich rhizosphere Oxalobacteraceae to improve maize performance under nitrogen deprivation
DOI:10.1038/s41477-021-00897-y
PMID:33833418
[本文引用: 1]
Beneficial interactions between plant roots and rhizosphere microorganisms are pivotal for plant fitness. Nevertheless, the molecular mechanisms controlling the feedback between root architecture and microbial community structure remain elusive in maize. Here, we demonstrate that transcriptomic gradients along the longitudinal root axis associate with specific shifts in rhizosphere microbial diversity. Moreover, we have established that root-derived flavones predominantly promote the enrichment of bacteria of the taxa Oxalobacteraceae in the rhizosphere, which in turn promote maize growth and nitrogen acquisition. Genetic experiments demonstrate that LRT1-mediated lateral root development coordinates the interactions of the root system with flavone-dependent Oxalobacteraceae under nitrogen deprivation. In summary, these experiments reveal the genetic basis of the reciprocal interactions between root architecture and the composition and diversity of specific microbial taxa in the rhizosphere resulting in improved plant performance. These findings may open new avenues towards the breeding of high-yielding and nutrient-efficient crops by exploiting their interaction with beneficial soil microorganisms.
Short-term effects of returning granulated straw on soil microbial community and organic carbon fractions in dryland farming
Consistent responses of soil microbial communities to elevated nutrient inputs in grasslands across the globe
/
〈 |
|
〉 |
![](../../../richhtml/1001-7283/richHtml_jats1_1/images/1.png)