Biopriming of seed with plant growth-promoting bacteria for improved germination and seedling growth

Abstract

Several seed priming methods can be used to improve seed germination, seedling vigor, and to overcome abiotic stress. In addition to these benefits, only the biopriming method provides the additional benefit of biotic stress management, earning it special attention. Seed biopriming is useful in almost all crops around the world and is an environmentally friendly alternative to chemical fungicides. Biopriming usually refers to use of beneficial microorganisms, in particular plant growth-promoting bacteria (PGPB) able to survive under various harsh environmental conditions. In this study, various bacterial strains were isolated from samples of different origins, i.e., rhizospheric soil, desert sand, and sea mud. Preliminary screening of 156 bacterial isolates was conducted on the basis of their potassium (K), phosphorus (P) solubilization ability, and production of plant growth hormone, i.e., indole acetic acid (IAA). The most efficient bacteria were identified by 16S rRNA gene nucleotide sequences and further examined for their ACC deaminase activity, ammonia production, and biocontrol activity (defined via chitinolytic activity, HCN, and siderophores production). Finally, carrot seed germination assay was conducted with 10 shortlisted most potent isolates. 68.6, 58.3, and 66.7% of tested bacterial isolates were capable of P, K, and Zn solubilization, respectively. Klebsiella aerogenes AF3II1 showed the highest P and K solubilization, while isolate AF4II5, AF7II3, and PC3 showed the highest IAA synthesis ability. Serratia plymuthica EDC15 and Pseudomonas putida AF1I1 showed the strongest chitinolytic and siderophore production activity, respectively. Seven isolates demonstrated strong HCN production ability. Five isolates improved carrot seed germination. Only selected isolates with plant growth-promoting properties can improve carrot germination. The results of this study demonstrate that mainly auxins are involved in seed germination. Furthermore, the data suggest that phosphate solubilization ability may play an additional role in seed germination.

Potential of Bacillus stercoris B.PNR2 to stimulate growth of rice and waxy corn under atrazine-contaminated soil

“…Even though plant growth-promoting activity, especially auxin production by bacteria, is usually related to seed germination (Fiodor et al, 2023), this effect did not occur in our study. For example, plant growth-promoting bacteria, including Serratia marcescens AF8I1, P. fluorescens AF8I4, P. putida AF1I1, Klebsiella aerogenes AF3II, and B. cereus AF8II1, could increase relative seed germination in carrots (Fiodor et al, 2023). Plant growth-promoting bacteria isolate T22 also increased germination in maize seeds (Rudolph et al, 2015).…”

Biocontrol potential of Pseudomonas protegens ML15 against Botrytis cinerea causing gray mold on postharvest tomato (Solanum lycopersicum var. cerasiforme)

“…A total of 8 plant growth promoting bacteria (PGPB) isolates from our previous study were used in this study ( Fiodor et al., 2023 ). Two ( Bacillus thuringiensis EDC1 and Serratia plymuthica EEPC5) bacterial isolates were previously isolated from carrot and parsley root samples, one ( Pseudomonas protegens ML15) from Błędowska Desert and five ( Burkholderia ambifaria AF8II10, Bacillus cereus AF8II13, Klebsiella aerogenes AF3II1, Pseudomonas putida AF1I1, Serratia marcescens AF8I1) from rhizospheric soil samples of cereal crops from Hołodolina, Niewodnica Nargilewska, and Hermanówka.…”

Plant Growth-Promoting Soil Bacteria: Nitrogen Fixation, Phosphate Solubilization, Siderophore Production, and Other Biological Activities

“…The ability of bacteria to solubilize potassium is assessed with agar containing mica powder (0.2%) as the single source of potassium. Bacterial cultures that form a clear zone are considered K solubilizers [ 97 , 98 ].…”

“…The ability of isolates to dissolve phosphorus is assessed by measuring the translucent halo around the colony. The phosphate solubilization index (PSI) and potassium solubilization index (KSI) are determined by calculation, using the equation in which the diameter of the clear zone is added to the colony diameter and the sum is divided by the colony diameter [ 98 , 99 ].…”