scholarly journals Evidence for Induced Systemic Protection to Fusiform Rust in Loblolly Pine by Plant Growth-Promoting Rhizobacteria

Plant Disease ◽  
2000 ◽  
Vol 84 (3) ◽  
pp. 306-308 ◽  
Author(s):  
S. A. Enebak ◽  
W. A. Carey

Trials conducted in 1997 and 1998 tested eight strains of plant growth-promoting rhizobacteria (PGPR) for their capacity to induce systemic protection in loblolly pine to the causal agent of fusiform rust. Pine seeds were treated with bacteria at time of sowing, and seedlings were artificially inoculated with basidiospores of Cronartium quercuum f. sp. fusiforme 1 month later. Six months after basidiospore inoculation, seedlings were evaluated for the fusoid swelling or galls characteristic of rust infection. Compared with seedlings from seed not treated with bacteria, two bacterial isolates, Bacillus pumilus (SE34) and Serratia marcescens (90–166), significantly (P = 0.05) reduced the number of galls in 1997 and 1998. Combined data from 1997 and 1998 resulted in two additional isolates, B. pumilus (INR7) and B. pumilus (SE52), significantly (P = 0.05) reducing the number of galls. Averaged over both years, 31% of control seedlings were infected with fusiform rust, while those seedlings treated with bacterial strains SE34, 90–166, INR7, and SE52 had 13, 14, 15, and 16% infection, respectively. These four PGPR strains appear to have induced systemic resistance to fusiform rust in loblolly pine, resulting in less infection over nontreated control seedlings.

2004 ◽  
Vol 28 (4) ◽  
pp. 185-188 ◽  
Author(s):  
S.A. Enebak ◽  
W.A. Carey

Abstract Fusiform rust caused by Cronartium quercuum f.sp. fusiforme (Hedg. & Hunt ex Cumm.) is the most damaging stem disease of Pinus spp. in the southern United States. Plant-growth-promoting rhizobacteria (PGPR) have induced systemic resistance in many host-pathogen systems. To determine whether rhizobacteria could induce systemic resistance to fusiform rust infection, loblolly pine (Pinus taeda L.) seedlings were evaluated for rust resistance following preemergence seed and post emergence foliar sprays with three bacterial strains. Treated seed was sown in one bare root nursery in Alabama and one in Georgia, and seedlings were examined for size differences and rust galls at the end of one season. Treatment with bacteria at the time of sowing did not affect rust galls or seedling growth at the Alabama nursery but reduced galls and increased seedling growth at the Georgia nursery. Bacterial treatment T4 resulted in significantly fewer galls and strains T4 and SE34 resulted in larger seedlings compared to nontreated controls. This is the first report of a reduction in fusiform rust by plant growth-promoting rhizobacteria and although nursery × treatment interactions exist, the current findings suggest that induced systemic resistance is possible. South. J. Appl. For. 28(4):185–188.


2017 ◽  
Vol 9 (1) ◽  
pp. 121-128
Author(s):  
S. Kumar ◽  
M. Singh ◽  
Sushil Sharma

The root rot disease in Jatropha curcas L. caused by Rhizoctonia. bataticola (Taub.) Butler has been recorded in causing 10-12 per cent mortality of 20-30 days old seedlings of Jatropha curcasin southern Haryana. The incidence of this disease has also been observed from other parts of Haryana too. Induction of systemic resistance in host plants through microbes and their bioactive metabolites are attaining popularity in modern agricultural practices. Studies on the plant growth-promoting rhizobacteria induced resistance in Jatropha curcas through phenyl propanoid metabolism against Rhizoctoniabataticola were undertaken at Chaudhary Charan Singh, Haryana Agricultural University, Regional Research Station, Bawal. Three plant growth-promoting rhizobacteria (PGPRs) viz., Pseudomonas maltophila, Pseudomonas fluorescens and Bacillus subtilis were evaluated for their potential to induce systemic resistance in Jatropha against root rot. The maximum increase of 97 per cent in total phenols, 120 per cent in peroxidase, 123 per cent in polyphenol oxidase, 101 per cent in phenylalanine ammonia lyase and 298 per cent in tyrosine ammonia lyase was detected in plants raised with Pseudomonas fluorescens+ Rhizoctoniaba-taticola inoculation in Jatropha curcas at 10 days post inoculation against control except total phenols where it was maximum (99%) at 30 DPI. There was slight or sharp decline in these parameters with age irrespective of inoculations. The pathogen challenged plants showed lower levels of total phenols and enzymes. The observations revealed that seed bacterization with Pseudomonas fluorescens results in accumulation of phenolics and battery of enzymes in response to pathogen infection and thereby induce resistance systemically.


2020 ◽  
pp. 1186-1194
Author(s):  
Roberta Mendes dos Santos ◽  
Everlon Cid Rigobelo

The search for plant growth-promoting rhizobacteria is an ongoing need for the development of new bioinoculants for use in various crops, including sugarcane. Bacterial strains with various plant growth-promoting properties can contribute to sustainable agricultural production. The present study aimed to isolate, characterize and select sugarcane rhizobacteria from six different varieties through principal components analysis. This study selected 167 bacterial strains with the ability to fix nitrogen, produce indolacetic acid, exhibit cellulolytic activity, and solubilize phosphate and potassium were isolated. Of these 167 bacterial strains, seven were selected by principal component analysis and identified as belonging to the genera Staphylococcus, Enterobacter, Bacillus and Achromobacter. Bacillus thuringiensis IP21 presented higher potential for nitrogen fixation and CaPO4 and AlPO4 solubilization and a lower potential for K solubilization in sugarcane. Enterobacter asburiae IP24 was efficient in indolacetic acid production and CaPO4 and FePO4 solubilization and inefficient for Araxá apatite solubilization.


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