Endophytes Crop Productivity and Protection Volume 2 (Sustainable Development and Biodiversity)

(Tina Meador) #1

7.7.5 Downy Mildew


Sixty different endophytic bacterial isolates belonging to different genera were iso-


lated from root and stem tissues offive medicinal plants (Cymbopogon citratus,


Azadirachta indica, Phyllanthus emblica, Boerhaavia diffusa and Boerhaavia


repens) and two agricultural crops (Pisum sativumandSorghum bicolor) and one


weed plant (Parthenium hysterophorus) and were tested against pearl millet downy
mildew disease. The peral millet seeds were treated with endophytic bacteria;


P.fluorescensISR 34 andBacillussp. ISR 37 recorded greater control of downy


mildew disease, by 68 and 63%, respectively. From the above results it is concluded


that the endophytic bacterial strains not only reduces the disease incidence but also


increased the plant growth by way of induced systemic resistance (Chandrashekhara


et al. 2007 ). Endophytic bacterial isolates obtained from cucumber leaves and tested


againstPseudoperonospora cubensiscausing downy mildew disease. The results


revealed that the strain CE8 recorded high level of inhibition againstP. cubensis.In


thefield test, the same strain showed high level of control efficacy (42.1%) and


disease reduction in cucumber. Further, the phylogenetic analysis based on 16S


rDNA identified the strains asBacillussp. (Sun et al. 2013 ).


7.7.6 Basal Stem Rot/Ganoderma Wilt/Thanjavur Wilt


An endophytic bacteriumPseudomonas cepacia(B3) andPseudomonas aerugi-


nosa(P3) isolated from root tissues of oil palm exhibited strong inhibition on the


growth ofG. boninensecausing ganoderma wilt (Dikin et al. 2003 ). Histological


studies revealed that bacteria endophytes confined to the vascular bundles of the


roots taken from symptomless palms (Zaiton et al. 2006 ). Total of 581 endophytic


bacteria were isolated from root tissues of oil palm and tested againstGanoderma
lucidumcause of wilt pathogen. Among these, three endophytic bacteria namely


Pseudomonas aeruginosa GanoEB1, Burkholderia cepacia GanoEB2, and


Pseudomonas syringaeGanoEB3 were highly effective in inhibiting the mycelia


growth of test pathogen. All the three isolates were underfield condition. The


results revealed that the only isolateP. aeruginosaGanoEB1 was highly effective


in controlling disease incidence of 13.3–26.7% compared to control (60%) (Ramli


et al. 2016 ).


7.7.7 Post Harvest Fungal Diseases


Finite efforts were made by using endophytic bacteria for the control of storage


diseases. Endophytic bacteria were tested to control stone fruit rot pathogens


Monilinia laxaandRhizopus stolonifer(Pratella et al. 1993 ). One hundred and


146 A. Muthukumar et al.


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