Paenibacillus polymyxa is a plant growth‐promoting rhizobacterium that has immense potential to be used as an environmentally friendly replacement of chemical fertilizers and pesticides. In the present study, Paenibacillus polymyxa SK1 was isolated from bulbs of Lilium lancifolium. The isolated endophytic strain showed antifungal activities against important plant pathogens like Botryosphaeria dothidea, Fusarium oxysporum, Botrytis cinerea, and Fusarium fujikuroi. The highest percentage of growth inhibition, i.e., 66.67 ± 2.23%, was observed for SK1 against Botryosphaeria dothidea followed by 61.19 ± 3.12%, 60.71 ± 3.53%, and 55.54 ± 2.89% against Botrytis cinerea, Fusarium fujikuroi, and Fusarium oxysporum, respectively. The metabolite profiling of ethyl acetate fraction was assessed through the UHPLC‐LTQ‐IT‐MS/MS analysis, and putative identification was done with the aid of the GNPS molecular networking workflow. A total of 29 compounds were putatively identified which included dipeptides, tripeptides, cyclopeptides (cyclo‐(Leu‐Leu), cyclo(Pro‐Phe)), 2‐heptyl‐3‐hydroxy 4‐quinolone, 6‐oxocativic acid, anhydrobrazilic acid, 1‐(5‐methoxy‐1H‐indol‐3‐yl)‐2‐piperidin‐1‐ylethane‐1,2‐dione, octadecenoic acid, pyochelin, 15‐hydroxy‐5Z,8Z,11Z, 13E‐eicosatetraenoic acid, (Z)‐7‐[(2R,3S)‐3‐[(2Z,5E)‐Undeca‐2,5‐dienyl]oxiran‐2‐yl]hept‐5‐enoic acid, arginylasparagine, cholic acid, sphinganine, elaidic acid, gossypin, L‐carnosine, tetrodotoxin, and ursodiol. The high antifungal activity of SK1 might be attributed to the presence of these bioactive compounds. The isolated strain SK1 showed plant growth‐promoting traits such as the production of organic acids, ACC deaminase, indole‐3‐acetic acid (IAA), siderophores, nitrogen fixation, and phosphate solubilization. IAA production was strongly correlated with the application of exogenous tryptophan concentrations in the medium. Furthermore, inoculation of SK1 enhanced plant growth of two Lilium varieties, Tresor and White Heaven, under greenhouse condition. In the light of these findings, the P. polymyxa SK1 may be utilized as a source of plant growth promotion and disease control in sustainable agriculture.

The present study was aimed at isolating endophytic fungi from the Asian culinary and medicinal plant Lilium davidii and analyzing its antifungal and plant growth‐promoting effects. In this study, the fungal endophyte Acremonium sp. Ld‐03 was isolated from the bulbs of L. davidii and identified through morphological and molecular analysis. The molecular and morphological analysis confirmed the endophytic fungal strain as Acremonium sp. Ld‐03. Antifungal effects of Ld‐03 were observed against Fusarium oxysporum, Botrytis cinerea, Botryosphaeria dothidea, and Fusarium fujikuroi. The highest growth inhibition, i.e., 78.39 ± 4.21%, was observed for B. dothidea followed by 56.68 ± 4.38%, 43.62 ± 3.81%, and 20.12 ± 2.45% for B. cinerea, F. fujikuroi, and F. oxysporum, respectively. Analysis of the ethyl acetate fraction through UHPLC‐LTQ‐IT‐MS/MS revealed putative secondary metabolites which included xanthurenic acid, valyl aspartic acid, gancidin W, peptides, and cyclic dipeptides such as valylarginine, cyclo‐[L‐(4‐hydroxy‐Pro)‐L‐leu], cyclo(Pro‐Phe), and (3S,6S)‐3‐benzyl‐6‐(4‐hydroxybenzyl)piperazine‐2,5‐dione. Other metabolites included (S)‐3‐(4‐hydroxyphenyl)‐2‐((S)‐pyrrolidine‐2‐carboxamido)propanoic acid, dibutyl phthalate (DBP), 9‐octadecenamide, D‐erythro‐C18‐Sphingosine, N‐palmitoyl sphinganine, and hydroxypalmitoyl sphinganine. The strain Ld‐03 showed indole acetic acid (IAA) production with or without the application of exogenous tryptophan. The IAA ranged from 53.12 ± 3.20 μg ml^-1 to 167.71 ± 7.12 μg ml^-1 under different tryptophan concentrations. The strain was able to produce siderophore, and its production was significantly decreased with increasing Fe(III) citrate concentrations in the medium. The endophytic fungal strain also showed production of organic acids and phosphate solubilization activity. Plant growth‐promoting effects of the strain were evaluated on in vitro seedling growth of Allium tuberosum. Application of 40% culture dilution resulted in a significant increase in root and shoot length, i.e., 24.03 ± 2.71 mm and 37.27 ± 1.86 mm, respectively, compared to nontreated control plants. The fungal endophyte Ld‐03 demonstrated the potential of conferring disease resistance and plant growth promotion. Therefore, we conclude that the isolated Acremonium sp. Ld‐03 should be further investigated before utilization as a biocontrol agent and plant growth stimulator.

Mohammad Sayyar Khan , Junlian Gao , Xuqing Chen , Mingfang Zhang , Fengping Yang , Yunfeng Du , The Su Moe , Iqbal Munir , Jing Xue and Xiuhai Zhang . J. Microbiol. Biotechnol. 2020;30:668-80. https://doi.org/10.4014/jmb.1910.10021

Microbial inoculants are an important tool for increasing arable land productivity and decreasing mineral fertilizer application. This study was aimed at isolating and identifying endophytic antagonistic bacteria from lily (Lilium davidii var. unicolor) roots grown in Northwestern China and at evaluating their antifungal activity and plant growth‐promoting characteristics. For this purpose, endophytic bacteria were isolated from plant roots, and plant growth‐promoting strains were identified. One bacterial strain, isolated from the root part, was identified as Bacillus halotolerans based on 16S rRNA gene sequence analysis and was designated as LBG‐1‐13. The strain showed antagonistic activities against important plant pathogens of lily including Botrytis cinerea, Botryosphaeria dothidea, and Fusarium oxysporum. The highest percentage of growth inhibition, i.e., 71.65 ± 2.39%, was observed for LBG‐1‐13 against Botryosphaeria dothidea followed by 68.33 ± 4.70% and 48.22 ± 4.11% against Botrytis cinerea and Fusarium oxysporum, respectively. Meanwhile, the isolated strain also showed plant growth‐promoting traits such as the production of indole‐3‐acetic acid (IAA), siderophore, ACC deaminase, and phosphate solubilization activity. The strain showed ACC deaminase activity and was able to cleave 58.41 ± 2.62 nmol α‐ketobutyrate (mg protein)^-1 min^-1. The strain exhibited tolerance to salt and drought stress in an in vitro experiment. The strain LBG‐1‐13 was able to grow in the presence of 10% NaCl and 20% polyethylene glycol (PEG) in the growth medium. Inoculation of Lilium varieties, Tresor and Bright Diamond, with LBG‐1‐13 enhanced plant growth under greenhouse and field conditions, respectively. All these results demonstrated that Bacillus halotolerans LBG‐1‐13 could be utilized as a good candidate in the biocontrol of lily disease and plant growth promotion in sustainable agriculture.

Lily (Lilium spp.) is a popular ornamental plant. Traditional genetic transformation methods have low efficiency in lily, thus development of a high-efficiency genetic transformation system is important. In this study, a novel transient transformation method involving pollen magnetofection was established and optimized pollen viability, and exogenous gene expression in magnetofected pollen and that of different germplasm were assessed. The highest germination percentage of Lilium regale pollen was 85.73% in medium containing 100 g/L sucrose, 61.5 mg/L H₃BO₃, and 91.5 mg/L CaCl₂. A 1:4 ratio of nanomagnetic beads to DNA plasmid and transformation time of 0.5 h realized the highest transformation efficiency (88.32%). The GFP activity in transformed pollen averaged 69.66%, while that of the control pollen was 0.00%. In contrast to the control, transgenic seedlings obtained by pollination with magnetofected pollen showed strong positive GUS activity with 56.34% transformation efficiency. Among the lily germplasm tested, ‘Sweet Surrender’ and L. leucanthum had the highest transformation efficiency (85.80% and 54.47%), whereas L. davidii var. willmottiae was not successfully transformed. Transformation efficiency was positively correlated with pollen equatorial diameter and negatively correlated with polar axis/equatorial diameter ratio. The results suggest that pollen magnetofection-mediated transformation can be applied in Lilium but might have species or cultivar specificity.