Quantitative proteomic analysis reveals altered enzyme expression profile in Zea mays roots during the early stages of colonization by Herbaspirillum seropedicae

Abstract

The use of plant growth-promoting bacteria as agricultural inoculants of plants should be encouraged because of their prominent role in biological nitrogen fixation, the increase of nutrient uptake by roots, abiotic stress mitigation, and disease control. The complex mechanisms underlying the association between plant and beneficial bacteria have been increasingly studied, and proteomic tools can expand our perception regarding the fundamental molecular processes modulated by the interaction. In this study, we investigated the changes in protein expression in maize roots in response to treatment with the endophytic diazotrophic Herbaspirillum seropedicae and the activities of enzymes related to nitrogen metabolism. To identify maize proteins whose expression levels were altered in the presence of bacteria, a label-free quantitative proteomic approach was employed. Using this approach, we identified 123 differentially expressed proteins, of which 34 were upregulated enzymes, in maize roots cultivated with H. seropedicae. The maize root colonization of H. seropedicae modulated the differential expression of enzymes involved in the stress response, such as peroxidases, phenylalanine ammonia-lyase, and glutathione transferase. The differential protein profile obtained in the inoculated roots reflects the effect of colonization on plant growth and development compared with control plants. K E Y W O R D S biostimulation, endophytes, label-free proteomics, N 2 -fixation 1 INTRODUCTION The enhanced use of fertilizers for supporting agriculture has led to deterioration of the environment [1]. Nitrogen fertilization of nonleguminous crops is one of the most expensive inputs to increase agri-cultural yields [2]. The use of plant growth-promoting bacteria (PGPB)as agricultural plant inoculants should be encouraged because of their prominent role in biological nitrogen fixation (BNF) and the increased root nutrient absorption, which mitigate abiotic stress and help in disease control. Herbaspirillum seropedicae has been studied because of its

Multiomic Approaches Reveal Hormonal Modulation and Nitrogen Uptake and Assimilation in the Initial Growth of Maize Inoculated with Herbaspirillum seropedicae

“…The diazotrophic bacterium H. seropedicae, can affect the nitrogen metabolism of the plant host [ 25 , 26 , 48 , 49 , 50 ]. Using transcriptomic and proteomic approaches, this study allowed us to better understand how inoculation can modulate nitrogen acquisition and metabolism.…”

The Impact of Non-Nodulating Diazotrophic Bacteria in Agriculture: Understanding the Molecular Mechanisms That Benefit Crops

“…Studies have shown that diazotrophic bacteria can upregulate important genes involved in nitrogen metabolism such as NR , NiR , and GS , which encode nitrate reductase, nitrite reductase, and glutamine synthetase, respectively, and collectively increase the activity of these enzymes in plants [ 11 , 21 , 76 , 77 , 78 , 79 ]. As illustrated in Figure 2 , the modulation of nitrogen metabolism results in higher N storage in the vacuole compartment, leading to better plant growth and development.…”

“…These endophytic and associative diazotrophic bacteria are considered plant growth–promoting rhizobacteria (PGPR), as they improve plant performance by enhancing the availability of nutrients and improve soil fertility, mainly through BNF and phosphate solubilization [ 17 , 18 , 19 ]. In addition, they produce plant growth regulators and are involved in the modulation of phytohormone and defense responses [ 20 , 21 , 22 ], production of antioxidants, osmotic adjustment, and plant tolerance against biotic and abiotic stresses [ 23 , 24 ]. A large number of important crops in agriculture are non-nodulating grasses, such as maize, rice, wheat, sorghum, and sugarcane, showing the importance of studies and production of bioinoculant non-nodulating diazotrophic bacteria.…”

Impact of historical soil management on the interaction of plant-growth-promoting bacteria with maize (Zea mays L.)

“…Alves et al [ 22 ] concluded that maize plants inoculated with Herbaspirillum seropedicae showed higher vegetative development under low N availability in the soil. These effects are related to biological nitrogen fixation (BNF) [ 23 ], modulation of enzymes in response to different types of stress [ 15 , 24 ], and/or bioprotection and mitigation of water stress [ [25] , [26] , [27] , [28] ] promoted by Herbaspirillum seropedicae.…”