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The Potential of Plant Microbiome on Improving Nitrogen-Use Efficiency in Cereal Crops
Improving nitrogen-use efficiency (NUE) is of top priority to agriculture worldwide. While the implementation of traditional breeding and genetic engineering are useful for enhancing crop NUE, the yield improvement resulting from conventional breeding is plateauing and the high variability in crop genome makes it difficult to determine the genetic basis of NUE. Recently, the manipulation of plant microbiome has emerged as a potential tool to improve the NUE of crops. Nonetheless, there is still a lack of a sophisticated approach to inoculate microbes onto plants. Therefore, the first study in this dissertation (chapter 2) presents the results of the evaluation of different inoculation methods for delivering three phylogenetically distinct bacteria to sorghum roots and rhizosphere. This study highlights the importance of tailoring the inoculation method based on the characteristic of each inoculant. In addition to improving the inoculation method, plant-microbe interactions may vary due to crop genotype and environmental conditions. Therefore in the second study (chapter 3), sorghum genotypes differing in NUE were inoculated with synthetic communities and their growth responses to inoculation under different N levels were monitored using an automated phenotyping system. This study highlights the crosstalk between sorghum genotype and environmental conditions (N-stress) in affecting sorghum phenotype and the interaction with inoculated microbes. In the third study (chapter 4), 24 diverse sorghum genotypes differing in NUE were grown in a field under different N levels and their associated bacteria communities as well as root metabolites were characterized. This study elucidates how sorghum genotypes differing in NUE modulate rhizosphere bacterial communities and highlights root metabolites as one possible factor ultimately resulting in the differentiation in NUE and belowground microbial communities across genotypes. Chapter 5 of this dissertation is a literature review that centers on how plants modulate the exudation of root metabolites to cope with abiotic stresses including N-deficiency and highlights some microbial interactions conditioned by root exudates. Taken together, this dissertation provides insights into the application of the plant microbiome to improve crop yield.
Chai, Yen Ning, "The Potential of Plant Microbiome on Improving Nitrogen-Use Efficiency in Cereal Crops" (2021). ETD collection for University of Nebraska-Lincoln. AAI28862948.