Complete genome sequence of Mycobacterium Mya-zh01, an endophytic bacterium, promotes plant growth and seed germination isolated from flower stalk of Doritaenopsis.

Abstract

No genomic sequence of Mycobacterium isolated from orchids has been reported yet; therefore, this study intends to analyze the complete genomic sequence of a growth-promoting Mycobacterium from orchid Doritaenopsis. Mycobacterium strain Mya-zh01 was isolated from the flower stalk of Doritaenopsis Jiuhbao Red Rose. Our results show that Mya-zh01 can effectively produce and secrete the plant growth hormone indole-3-acetic acid (IAA). Inoculation of Mya-zh01 increased root number and length, plant height, leaf number, and leaf length in Doritaenopsis. Furthermore, inoculation of Mya-zh01 promotes seed germination in Doritaenopsis. We sequenced and assembled chromosome for Mya-zh01 (5,027,704bp with 68.48% GC content), which was predicted to encode 4968 proteins with functions in oxidation reduction, growth, plasma membrane, ATP and DNA binding, carbon metabolism and biosynthesis of amino acids pathways. Mya-zh01 may trap iron from nature or host cells to facilitate the growth of the orchids by producing two siderophores (Mycobactin and Nocobactin NA). Four pathways (tryptamine, indole-3-acetamide, indole-3-pyruvate, and flavin monooxygenase) and seven enzymes [tryptophan synthase alpha chain, tryptophan synthase beta chain, amidase, monoamine oxidase, indole-3-pyruvate monooxygenase, indole-3-pyruvate decarboxylase and aldehyde dehydrogenase (NAD +)] involved in IAA biosynthesis were predicted in Mya-zh01 genome. In conclusion, this study demonstrated the significance of Mya-zh01 in facilitating plant growth and seed germination in Doritaenopsis by IAA biosynthesis, which provides a new insight into the mechanism of plant-bacteria interaction in Doritaenopsis.