Characteristics of endophytic bacterial community structure in roots of sugarcane under different fertilizer applications

Abstract

<p id="C3">To explore the beneficial endophytic bacteria in sugarcanes and their functions, we analyzed the characteristics of endophytic bacterial community structure in roots of sugarcane under different fertilizer applications. At the phylum level, the proportion of Actinobacteria in roots of sugarcanes under different fertilization levels were lower than that in the control. However, the proportion of Chloroflexi in roots of sugarcanes under different fertilization levels applications were higher than that in CK. At the genus level, <italic>Haliangium</italic>, <italic>Acidicapsa</italic>, <italic>unclassified_f__Ktedonobacteraceae</italic>, and <italic>unclassified_f__Acidobacteriaceae_ Subgroup_</italic>1 were the specific dominant endophytic bacterial genera in root of sugarcanes under conventional fertilization level (3000 kg hm^-2, H treatment); while <italic>Sphingomonas</italic> was the specific dominant endophytic bacterial genus in roots of sugarcanes under fertilization level (1500 kg hm^-2, M treatment); <italic>Mesorhizobium</italic>, <italic>norank_f__BIrii</italic>41, <italic>Glycomyces</italic>, <italic>norank_f__</italic>67-14, <italic>Reyranella</italic>, <italic>unclassified_f__Steroidobacteraceae</italic>, <italic>unclassified_f__Xanthobacteraceae</italic>, <italic>norank_f__Roseiflexaceae</italic>, and <italic>Dongia</italic> were the specific dominant endophytic bacterial genus in roots of sugarcanes under the fertilization level (300 kg hm^-2, L treatment). On the contrary, <italic>Caulobacter</italic>, <italic>Pseudonocardia</italic>, <italic>Nocardia</italic>, <italic>Kitasatospora</italic>, <italic>norank_f__norank_o__norank_c__Actinobacteria</italic>, <italic>Oceanibaculum</italic>, and <italic>Amycolatopsis</italic> were the unique dominant endophytic bacterial genera in root of sugarcane without fertilization application (control). And <italic>Actinospica</italic>, <italic>Catenulispora</italic>, <italic>Acidothermus</italic>, <italic>Dyella</italic>, and <italic>norank_f__Xanthobacteraceae</italic> were lost in root of sugarcanes under low nitrogen applications. Gene function prediction also revealed that, compared to no-fertilization treatment, both the endophytic bacterial community structure and the metabolic functions of endophytic bacteria in roots of sugarcanes were affected by different fertilizer applications. However, the structures of endophytic bacterial community in roots of sugarcane were significant differences among different fertilization treatments depending on the amounts of fertilizer applications. Compared to conventional fertilization, the yields of sugarcanes, and the structure, metabolic function of endophytic bacteria in roots of sugarcanes were not significantly changed by fertilizer application under 1500 kg hm^-2 treatment. In conclusion, the conventional fertilization at the present stage can be substituted by reducing fertilizer application from 3000 kg hm^-2 to 1500 kg hm^-2 level in sugarcane.