Ujvári Gergely, Capo Luca, Grassi Arianna, Cristani Caterina, Pagliarani Irene, Turrini Alessandra, Blandino Massimo, Giovannetti Manuela, Agnolucci Monica
Department of Agriculture, Food and Environment, University of Pisa, Pisa, Italy.
Department of Agriculture, Forest and Food Sciences, University of Turin, Grugliasco, Italy.
Front Plant Sci. 2023 Nov 2;14:1240310. doi: 10.3389/fpls.2023.1240310. eCollection 2023.
The sustainable intensification of maize-based systems may reduce greenhouse-gas emissions and the excessive use of non-renewable inputs. Considering the key role that the microbiological fertility has on crop growth and resilience, it is worth of interest studying the role of cropping system on the rhizosphere bacterial communities, that affect soil health and biological soil fertility. In this work we monitored and characterized the diversity and composition of native rhizosphere bacterial communities during the early growth phases of two maize genotypes of different early vigor, using a nitrogen (N)-phosphorus (P) starter fertilization and a biostimulant seed treatment, in a growth chamber experiment, by polymerase chain reaction-denaturing gradient gel electrophoresis of partial 16S rRNA gene and amplicon sequencing. Cluster analyses showed that the biostimulant treatment affected the rhizosphere bacterial microbiota of the ordinary hybrid more than that of the early vigor, both at plant emergence and at the 5-leaf stage. Moreover, the diversity indices calculated from the community profiles, revealed significant effects of NP fertilization on richness and the estimated effective number of species () in both maize genotypes, while the biostimulant had a positive effect on plant growth promoting community of the ordinary hybrid, both at the plant emergence and at the fifth leaf stage. Our data showed that maize genotype was the major factor shaping rhizosphere bacterial community composition suggesting that the root system of the two maize hybrids recruited a different microbiota. Moreover, for the first time, we identified at the species and genus level the predominant native bacteria associated with two maize hybrids differing for vigor. These results pave the way for further studies to be performed on the effects of cropping system and specific crop practices, considering also the application of biostimulants, on beneficial rhizosphere microorganisms.
以玉米为基础的系统的可持续集约化可能会减少温室气体排放以及不可再生投入物的过度使用。考虑到微生物肥力对作物生长和恢复力的关键作用，研究种植系统对根际细菌群落的作用是值得关注的，因为根际细菌群落会影响土壤健康和土壤生物肥力。在这项研究中，我们在生长室实验中，通过对部分16S rRNA基因进行聚合酶链反应-变性梯度凝胶电泳和扩增子测序，监测并表征了两种不同早期活力的玉米基因型在早期生长阶段本地根际细菌群落的多样性和组成，实验采用了氮（N）-磷（P）基肥和生物刺激剂种子处理。聚类分析表明，在植株出苗期和5叶期，生物刺激剂处理对普通杂交种根际细菌微生物群的影响比对早期活力杂交种的影响更大。此外，根据群落图谱计算的多样性指数显示，NP施肥对两种玉米基因型的丰富度和估计有效物种数（）均有显著影响，而生物刺激剂在植株出苗期和第五叶期对普通杂交种的植物生长促进群落有积极影响。我们的数据表明，玉米基因型是塑造根际细菌群落组成的主要因素，这表明两种玉米杂交种的根系招募了不同的微生物群。此外，我们首次在物种和属水平上鉴定了与两种活力不同的玉米杂交种相关的主要本地细菌。这些结果为进一步研究种植系统和特定作物栽培措施（包括生物刺激剂的应用）对有益根际微生物的影响铺平了道路。
