An Endophytic Pseudonocardia Species Induces the Production of Artemisinin in Artemisia annua

Abstract

Endophytic actinobacteria colonize internal tissues of their host plants and are considered as a rich and reliable source of diverse species and functional microorganisms. In this study, endophytic actinobacterial strain YIM 63111 was isolated from surface-sterilized tissue of the medicinal plant Artemisia annua. We identified strain YIM 63111 as a member of the genus Pseudonocardia. A. annua seedlings grown under both sterile and greenhouse conditions were inoculated with strain YIM 63111. The growth of A. annua seedlings was strongly reduced when YIM 63111 was inoculated at higher concentrations under sterile conditions. However, no growth inhibition was observed when A. annua was grown under greenhouse conditions. Using an enhanced green fluorescent protein (EGFP) expressing YIM 63111 strain, we also observed the endophytic colonization of A. annua seedling using confocal laser-scanning microscopy. The transcription levels of the key genes involved in artemisinin biosynthesis were investigated using real time RT-PCR, revealing that cytochrome P450 monooxygenase (CYP71AV1) and cytochrome P450 oxidoreductase (CPR) expression were up-regulated in A. annua upon inoculation with strain YIM 63111 under certain conditions. The up-regulation of these genes was associated with the increased accumulation of artemisinin. These results suggest that endophytic actinobacteria effectively stimulate certain plant defense responses. Our data also demonstrate the use of Pseudonocardia sp. strain YIM 63111 as a promising means to enhance artemisinin production in plants.

Endophytic Bacterium-Triggered Reactive Oxygen Species Directly Increase Oxygenous Sesquiterpenoid Content and Diversity in Atractylodes lancea

“…The interactions between endophytes and plants can vary from mutualism to parasitism (44). The asymptomatic colonization of plants by endophytes is a delicate balance of antagonism between endophytes and host plants, during which plant secondary metabolites play essential roles (45).…”

Kill or cure? The interaction between endophytic Paenibacillus and Serratia strains and the host plant is shaped by plant growth conditions

“…Of interest, some of the rhizobacteria studied by the authors also damaged roots of the seedlings grown in germination pouches. Another study (Li et al 2012) describes an endophytic actinobacterial strain that stunted the root development of Artemisia annua seedlings grown under sterile conditions when inoculated at higher concentrations. The same strain did not show effects on the growth of A. annua under greenhouse conditions.…”

Involvement of abscisic acid and salicylic acid in signal cascade regulating bacterial endophyte‐induced volatile oil biosynthesis in plantlets of Atractylodes lancea

“…). Li et al () reported that elicitors can regulate gene expressions of enzymes for side chain modifications during the later stages of biosynthesis and thereby alter the constituent ratios of plant secondary metabolite. Thus, our results imply that the promotional model depends on the characteristics of diverse endophytes and that the simultaneous inoculation of endophytes with a variety of beneficial models might facilitate an oriented or synergistic biosynthesis of targeted bioactive products of plants.…”

“…and actinobacterium Pseudonocardia sp. in glasshouse experiments (Li et al , Tiwari et al ). Nevertheless, studies have rarely considered the underlying signaling mechanisms whereby endophytic bacteria may affect the secondary metabolism of plants.…”