Nanomaterials for management of Plant Diseases

              Plant pathologists made a late start in harnessing the benefits of nanomaterials for management of plant pathogens. There have been some exciting results obtained especially in plant disease management aspects concerning fungi, bacteria and flowering plant parasite by developing nanoparticles of different metals, pesticides and growth promoter

Nanosized silver:

              Silver (Ag) is known to have antimicrobial activity both in ionic or nanoparticle forms. The powerful antimicrobial effect of silver especially in unicellular microorganisms is believed to be brought about by enzyme inactivation (Kim et al., 1998). Antifungal effect of nano silver colloids (average diameter of 1.5 nm) was studied against the powdery mildew pathogen of rose caused by Sphaerotheca pannosa var. rosae. Silver is now an accepted agrochemical replacement’ and maximum no. of patents are filed for ‘nano silver’ for preservation and treatment of diseases in agriculture field (Sharon et al., 2010).

Nanosized silica-silver:

              Silica is well known to enhance stress resistance to plants including plant diseases through promotion of plant physiological activity and growth (Kanto et al., 2004) but it has no direct antimicrobial effect. It was found that smaller size of silver nanoparticles was more effective against fungi. Most of the bacteria tested were inhibited completely with only 100 ppm of silica-silver nanoparticles. When nanosized silica-silver particles were applied in field condition to control powdery mildew diseases of cucurbits, 100% control was achieved after 3 weeks (Park et al., 2006). Nanosized silica silver inhibited the growth and development of both Gram-positive and Gram-negative bacteria.

Mesoporous silica nanoparticles:

              These are silica (SiO₂) nanoparticles with regularly arranged pores which increase the surface area of the nanoparticles. Targeted delivery of chemicals and DNA can be made by mesoporous silica nanoparticles (Wang et al., 2002). It offers the possibility of genetic manipulation of plants, delivery of chemicals at targeted site in plant, improve efficiency of used chemical and reduce the chemical residue problem to the minimum. Nano-copper: Nano-copper was reported to be highly effective in controlling bacterial diseases viz. bacterial blight of rice (Xanthomonas oryzae pv. oryzae) and leaf spot of mung (X. campestris pv. phaseoli) (Gogoi et al., 2009).

Nano-iron:

              Movement and behaviour of nanoparticles and their curative affect is being studied more extensively involving humans. Similar study to deliver the nanoparticles in the targeted site of a diseased plant has been done by Corredor et al. (2009). They applied iron nanoparticles coated with carbon to pumpkin plants for treating specific plant part that is infected.

Carbon nanotubes:

              Carbon nanotubes have shown growth enhancing effect on tomato when grown in soil containing carbon nanotubes (Khodakovsky et al., 2000). It is believed that carbon nanotubes entered the germinating tomato seeds thus facilitating water uptake and plant growth.

Pesticide nanoformulations

Manufacturers are developing nanoformulations of existing fungicidal compounds by reducing the size of active ingredients to nanoscale and also by nanoencapsulating them.

Syngenta have developed fungicide formulation containing nanoparticles for example Banner MAXX Fungicide (active ingredient propiconazole), Apron MAXX (active ingredient fludioxonil) RFC for seed treatments. Similarly, cyclopropyl derivative of cyclohexenone (Primo MAXX) has been developed as plant growth regulator but it helps the plant in withstanding abiotic as well as biotic stresses including plant pathogens (Gogoi et al., 2009)

              A product of nanotechnology research in agriculture with the name of ‘Nano-Gro’ has been launched (Agro Nanotechnology Corp., Florida, http://www.agronano.com). Plants treated with ‘Nano-Gro’ show an average yield increase of 20% with maximum of 50% in case of grain yield of sunflower; increase in protein and sugar content by about 10% and plants can fight various diseases. The product is certified to be an organic one and harmless to plants and soil. ‘Nano Green’ a product prepared by mixing several bio-based chemicals was reported to eliminate blast disease (Magnaporthe grisea) from infected rice plant. The test was conducted in University of Georgia and the product was found to outperform any other pesticide or fungicides currently in use in agriculture (Gogoi et al., 2009).

Conclusion:

1. By using Nanotechnology and Genetic engineering techniques on hard core basis we can arrest the loses caused due to plant diseases.

2. Transfer of desirable genes for disease resistance can achieved through Nanobiotechnology.

REFERENCES:

Banik, S. and P. Sharma, 2011. Plant Pathology in era of nanotechnology. Indian           Phytopathol, 64(2) :120-127.

M. R. Khan and T. F Rizvi, 2014.  Nanotechnology: Scope and application in Plant Disease           Management, Pl. Pathol. J. 13(3) : 214-231

Article compiled by Mr. Amol Vijay Shitole (Ph.D. Scholar)

Dr. Panjabrao Deshmukh Krishi Vidyapeeth, Akola (M.S.)