Abstract
Cold stress decreases the growth and productivity of agricultural crops. Psychrotolerant plant growth-promoting bacteria (PGPB) may protect and promote plant growth at low temperatures. The aims of this study were to isolate and characterize psychrotolerant PGPB from wild flora of Andes Mountains and Patagonia of Chile and to formulate PGPB consortia. Psychrotolerant strains were isolated from 11 wild plants (rhizosphere and phyllosphere) during winter of 2015. For the first time, bacteria associated with Calycera, Orites, and Chusquea plant genera were reported. More than 50% of the 130 isolates showed ≥33% bacterial cell survival at temperatures below zero. Seventy strains of Pseudomonas, Curtobacterium, Janthinobacterium, Stenotrophomonas, Serratia, Brevundimonas, Xanthomonas, Frondihabitans, Arthrobacter, Pseudarthrobacter, Paenarthrobacter, Brachybacterium, Clavibacter, Sporosarcina, Bacillus, Solibacillus, Flavobacterium, and Pedobacter genera were identified by 16S rRNA gene sequence analyses. Ten strains were selected based on psychrotolerance, auxin production, phosphate solubilization, presence of nifH (nitrogenase reductase) and acdS (1-aminocyclopropane-1-carboxylate (ACC) deaminase) genes, and anti-phytopathogenic activities. Two of the three bacterial consortia formulated promoted tomato plant growth under normal and cold stress conditions. The bacterial consortium composed of Pseudomonas sp. TmR5a & Curtobacterium sp. BmP22c that possesses ACC deaminase and ice recrystallization inhibition activities is a promising candidate for future cold stress studies.
Highlights
The production and quality of agricultural crops are decreased by a wide range of abiotic stresses, including cold and high temperatures, drought, and salinity
One hundred three strains were isolated from the rhizosphere, whereas twenty-seven strains belong to the phyllosphere of plants (Table 2)
106 cells g−to therichness number and of bacteria in the rhizosphere reach up than to 108the cells g−1 losphere of plants. This bacterial diversity is correlated with the total commudry weight [65]. This is the first study of bacteria associated with Calycera, Orites, nity
Summary
The production and quality of agricultural crops are decreased by a wide range of abiotic stresses, including cold and high temperatures, drought, and salinity. Every year agriculture worldwide is affected by low temperatures, which are Microorganisms 2021, 9, 538. Climate change affects the natural systems, human health, and agricultural production [4], and with the increase in temperature, the cold acclimatization of plants occurs later in autumn or early winter [5]. This disorganized cold acclimatization causes a higher susceptibility of plants to erratic temperature events [5]. Cold stress is an important challenge for agriculture [3,6,7]
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