Improved germination efficiency of Salicornia ramosissima seeds inoculated with Bacillus aryabhattai SP1016‐20

Abstract

Funding information CESAMSaline agriculture and the crop cultivation of halophytes represent an alternative for the reclamation of salinized soils and for the management of irrigation water. Halotolerant plant growth promoting bacteria with biocontrol effect, as an alternative to commercial fungicides, may contribute to improve crop productivity while mitigating saline stress effects. The objective of this work was to isolate autochthonous rhizobacteria with biocontrol features, to be used as germination enhancers and plant-growth promoting agents in the crop cultivation of Salicornia ramosissima. A set of isolates obtained from the rhizosphere of S. ramosissima was characterised in terms of Gram, motility, salt tolerance and biocontrol traits (hydrogen cyanide production, antifungal activity and production of extracellular lipases and proteases). One Gram-positive motile isolate that tested positive for all biocontrol traits was identified by 16S rRNA gene sequencing as Bacillus aryabhattai. The inoculation of S. ramosissima seeds with B. aryabhattai SP1016-20 reduced the negative effect of salinity on the germination efficiency. At the highest tested salinity (30 g/L NaCl) the final germination efficiency of inoculated seeds doubled in relation to noninoculated controls. Although the mechanisms involved in the biocontrol effect were not defined in the current work, the results highlight the potential of Bacillus aryabhattai SP1016-20 as a plant-growth promoting agent for the crop cultivation of Salicornia and contribute to the strengthening of the scientific basis of biosaline agriculture and plant growth promoting rhizobacteria-assisted crop cultivation of halophytes in saline soils and estuarine sediments. K E Y W O R D S

Experimental evidence of strong relationships between soil microbial communities and plant germination

“…Our microcosm experiment provides experimental evidence to support the importance of soil biodiversity as a driver of the germination of plants in our study. Moreover, findings from this experiment provide support for research that strengthens work on microbially assisted plant cultivation (Figueira et al., 2019) or development towards greater resistant to unfavourable environmental conditions. For example, inoculating barley plants with the root‐colonizing fungus Piriformospora indica has been shown to increase its tolerance to both fungal disease and salt tolerance (Waller et al., 2005).…”

The Root Microbiome of Salicornia ramosissima as a Seedbank for Plant-Growth Promoting Halotolerant Bacteria

“…B. aryabhattai expressed all the tested extracellular enzymes. It also produces HCN, inhibits the phytopathogenic fungus Alternaria and increases the germination of S. ramosissima seeds at high salinities [26]. These isolates are promising candidates in the consortia of PGPB to be used as inoculants for saline or traditional agriculture.…”

“…Culture-dependent approaches directed to Salicornia species provide PGPR that effectively attenuates saline stress effects in halophytes [24][25][26][27] and non-halophyte crops [28,29]. Halotolerant Proteobacteria (Pseudomonas, Variovorax, Xanthomonas), Firmicutes (Bacillus, Planococcus, Staphylococcus) and Actinobacteria (Arthrobacter, Curtobacterium, Microbacterium) exhibiting plant-growth promoting traits have been retrieved from the endosphere or rhizosphere of S. ramosissima (or S. europaea) [24,25,[28][29][30].…”

Halotolerant Marine Rhizosphere-Competent Actinobacteria Promote Salicornia bigelovii Growth and Seed Production Using Seawater Irrigation

“…Mapelli et al (2013) have reported that the marine bacteria are capable of colonizing Salicornia roots in vitro. Many reports have focused on isolating bacterial strains from Salicornia rhizosphere (Rueda-Puente et al, 2004;Ozawa et al, 2007;Jha et al, 2012;Figueira et al, 2019).…”