Special events

Dr. Sheng Qin's groupmade progresses in plant-associated microbes


Soilsalinity is one of the major stresses that limit global agriculturalproductivity, affecting more than 45 million ha of irrigated land worldwide.Some plants, termed halophytes, have evolved complex mechanisms to adapt tosaline stress. Plant-associated microorganismsare considered a key determinant of plant healthand growth. However, little information is available regarding thecomposition and ecological function of the roots and leaves bacterialmicrobiota of halophytes. In our previous study, our group isolatedmany endophytic and rhizosphere bacteria from coastal halophyte Limonium sinense, and obtained somepotential PGP strains using seedlings inoculation on MS medium under saltstress (Qin et al., Plant Soil, 2014, 374:753–766). Three strainsof the genera Streptomyces, Bacillus and Arthrobacter could significantly promote host growth under saltstress. Recently, plant growth-promoting effect using pot experiments and plantphysiological analysis by two beneficial endophytes of the genera Streptomyces and Bacillus isolated from halophyte Limonium sinense were studied (Qin etal., Plant Soil, 2017, 416:117–132). The genomesof the strains were also sequenced and analyzed (Wang et al., Journal of Biotechnology, 2017, 260: 38-41).These studies are helpful to understand how endophytes help host plants grow insalt marshes environment. Using both culture-dependent and culture-independenttechniques, we characterized the bacterial communities of theroots, leavesas well as the rhizosphereand bulk soils ofthe coastal halophyte Limoniumsinense in Jiangsu Province, China. We found that Glutamicibacter was the most dominant genus. All Glutamicibacterisolatesshowed multiple potential plant growth promotion traits, and tolerated high concentration of NaCl and wide pH range.Interestingly, further inoculation experiments showed that the new species Glutamicibacter halophytocolaKLBMP5180(Feng et al., Int J Syst Evol Microbiol,2017, 67(5): 1120-1125) isolated from root tissue significantly promoted hostgrowth under NaCl stress. Indeed, KLBMP 5180 inoculation increased theconcentrations of total chlorophyll, proline, anti-oxidative enzymes,flavonoids, K+, and Ca2+ in the leaves; concentrations ofmalondialdehyde (MDA) and Na+ werereduced. Transcriptome analysisrevealed that pathways related to phenylpropanoid and flavonoid biosynthesis,and ion transport and metabolism might play more important roles in hostsalt-stress tolerance induced by KLBMP 5180 inoculation compared tonon-inoculated leaves. Our results provided novel insights into the complexcomposition and function of the bacterial microbiota of coastal halophyteL. sinense, and suggested thathalophytes might recruit specificbacteria to enhance their tolerance of harsh environments (Qin et al., Appl EnvironMicrobiol, 2018, 84:e01533-18). Besides, weassessed actinobacterial diversity from eight coastal salt marsh rhizosphere soils from Jiangsu Province, China, usingculture-based and 16S rRNA gene high throughput sequencing methods. Actinobacterialsequences represented 2.8%–43.0% of rhizosphere bacterial communities, asdetermined by HTS technique. The 92 representative cultured strains comprisedseven suborders, 12 families, and 20 genera that included several potentialnovel species (Dinget al.,Int J Syst Evol Microbiol, 2018, 68:192–197). Two strains were selected forinoculation of wheat seeds grown under salt stress. Our study demonstrates thatcoastal salt marsh rhizosphere soils harbor a diverse reservoir ofActinobacteria that are potential resources for the discovery of novel speciesand functions (Gong et al., Syst Appl Microbiol, 2018, 41:516–527).