Omics of the early molecular dialogue between Frankia alni and Alnus glutinosa and the cellulase synton

Abstract

Summary The early Frankia‐Alnus symbiotic molecular exchanges were analyzed in detail by protein and RNA omics. For this, Frankia cells were placed in the presence of Alnus roots but separated by a dialysis membrane for 64 h. The bacterial cells were then harvested and analyzed by high‐throughput proteomics and transcriptomics (RNA‐seq). The most upregulated gene clusters were found to be the potassium transporter operon kdp and an ABC transporter operon of uncharacterized function. The most upregulated proteins were found to be acyl dehydrogenases and the potassium transporter Kdp. These suggest a preadaptation to the impending stresses linked to the penetration into isotonic host tissues and a possible rearrangement of the membrane. Another cluster among the 60 most upregulated ones that comprised two cellulases and a cellulose synthase was conserved among the Frankia and other actinobacteria such as Streptomyces. Cellulase activity was detected on CMC all along the length of the root but not away from it. Frankia alni ACN14a was found to be unable to respire or grow on glucose as sole carbon source. The cellulose synthase was found active at the tip of hyphae in response to Alnus root exudates, resulting in a calcofluor stained tip.

The non-specific Lipid Transfer Protein (nsLTP) is involved at early and late stages of symbiosis between Alnus glutinosa and Frankia alni

“…Plant samples at early stages of infection were obtained as described previously(Pujic et al ., 2019). Briefly, Frankia alni ACN14a (Normand & Lalonde, 1982) was grown in BAP-PCM media until log-phase, collected by centrifugation, washed twice with sterile ultra-pure water and suspended in Farhaeus medium without KN03.…”

“…The same approach used previously (10), was used here to obtain plant samples at an early stage of infection for RNA extraction. Briefly, Frankia alni ACN14a (23) was grown in BAP-PCM media until log-phase, collected by centrifugation, washed twice with sterile ultra-pure water and suspended in Farhaeus medium without KN03.…”

“…In mature nodules, the bacterial genes nif, hup, shc and suf are upregulated but no trace of a symbiotic island was found (Alloisio et al ., 2010). A study of the Frankia alni early response (2.5 dpi) showed that several determinants were upregulated among which a K-transporter, lipid modifying enzymes and a conserved cellulose synthase cluster (Pujic et al ., 2019). Proteomics was performed on a related species, Frankia coriariae that unravelled an upregulation of cell wall remodelling enzymes, signal transduction and host signal processing proteins (Ktari et al ., 2017).…”

Advanced Proteomics as a Powerful Tool for Studying Toxins of Human Bacterial Pathogens

“…While new generations of instruments are proposed almost every year with improved performances in terms of sensitivity, resolution, and speed, increased coverage of the proteome is expected in terms of the number of proteins and their sequence coverage, as well as a more precise quantitation of these proteins. Currently, an instrument such as a Q-Exactive HF tandem mass spectrometer which is considered as a workhorse for proteomics allows us to identify up to 2000 proteins from a bacterial extract in a single 90 min run [120,121] and up to 4000 from a yeast extract [122]. The most recent tandem mass spectrometers allow microbiologists entering in the complete proteome era.…”

Spotlight on how microbes influence their host's behavior

“…Indeed, besides articles on animal hosts (Koehler et al, 2018;Murfin et al, 2018;Truitt et al, 2018;Altinli et al, 2019;Rothman et al, 2019;Zhao et al, 2019), this special issue contains a number of research papers devoted to understanding how plants respond to their microbial inhabitants. Among these studies on plant-symbiont interactions, several focus on plant responses to nitrogen-fixing bacteria (Lamouche et al, 2018;Baena et al, 2019;Bañuelos-Vazquez et al, 2019;Pujic et al, 2019;Songwattana et al, 2019), while others investigate endophytes and their role in alleviating plant abiotic stress (Vigani et al, 2018;Lanza et al, 2019;Llorens et al, 2019).…”