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Biostimulants in Agriculture

Original Research ARTICLE Provisionally accepted The full-text will be published soon. Notify me

Front. Plant Sci. | doi: 10.3389/fpls.2018.01959

Exposure in vitro to an environmentally isolated strain TC09 of Cladosporium sphaerospermum triggers plant growth promotion, early flowering and fruit yield increase.

 Zhijian Li1, Wojciech Janisiewicz1, Zongrang Liu1,  Ann Callahan1,  Breyn Evans1, Wayne Jurick2 and  Chris Dardick1*
  • 1Appalachian Fruit Research Station (ARS-USDA), United States
  • 2Beltsville Agricultural Research Center, Agricultural Research Service (USDA), United States

A growing number of bacteria and fungi have been found to produce volatile organic compounds (VOCs) that can promote plant growth. Here we report the identification of an environmentally isolated strain of Cladosporium sphaerospermum (herein named TC09), that substantially enhances plant growth via VOCs beyond what has previously been reported. When cultured on Murashige and Skoog (MS) medium under in vitro conditions, tobacco seedlings (Nicotiana tabacum) exposed to TC09 cultures for 20 days increased stem height and whole plant biomass up to 25- and 15-fold, respectively, over controls without exposure. TC09-mediated growth promotion required >5 g/L sucrose in the plant culture medium and was influenced by the duration of exposure ranging from one to ten days, beyond which no differences were detected. When transplanted to soil under greenhouse conditions, TC09-exposed tobacco plants retained higher rates of growth. Comparative transcriptome analyses using tobacco seedlings exposed to TC09 for 10 days uncovered differentially expressed genes (DEGs) associated with diverse biological processes including cell expansion and cell cycle, photosynthesis, phytohormone homeostasis and defense responses. To test the potential efficacy of TC09-mediated growth promotion on agricultural productivity, pepper plants (Capsicum annuum L.) of two different varieties, Cayenne and Minisweet, were pre-exposed to TC09 and planted in the greenhouse to monitor growth, flowering, and fruit production. Results showed that treated pepper plants flowered 20 days earlier and yielded up to 213% more fruit than untreated controls. Altogether the data suggest that exposure of young plants to C. sphaerospermum produced VOCs may provide a useful tool to improve crop productivity.

Keywords: Microbial volatile organic compounds, Cladosporium sphaerospermum, plant growth promotion, biostimulant, Nicotiana tabacum (L.), Capsicum annuum L., expression profiling

Received: 26 Sep 2018; Accepted: 17 Dec 2018.

Edited by:

Giuseppe Colla, Università degli Studi della Tuscia, Italy

Reviewed by:

Antonio Ferrante, University of Milan, Italy
Philipp Franken, Leibniz-Institut für Gemüse- und Zierpflanzenbau (IGZ), Germany
Paolo Bonini, Ngalab (Spain), Spain  

Copyright: © 2018 Li, Janisiewicz, Liu, Callahan, Evans, Jurick and Dardick. This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) and the copyright owner(s) are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms.

* Correspondence: Dr. Chris Dardick, Appalachian Fruit Research Station (ARS-USDA), Kearneysville, West Virginia, United States, chris.dardick@ars.usda.gov