Inactivation of plant infecting fungal and viral pathogens to achieve biological containment in drainage water using UV treatment

Abstract

Aim: To explore whether ultraviolet (UV) light treatment within a closed circulating and filtered water drainage system can kill plant pathogenic species. Methods and Results: Ultraviolet experiments at 254 nm were conducted to determine the inactivation coefficients for seven plant pathogenic species. At 200 mJ cm−2, the individual species log reductions obtained for six Ascomycete fungi and a cereal virus were as follows: Leptosphaeria maculans (9·9‐log), Leptosphaeria biglobosa (7·1‐log), Barley stripe mosaic virus (BSMV) (4·1‐log), Mycosphaerella graminicola (2·9‐log), Fusarium culmorum (1·2‐log), Fusarium graminearum (0·6‐log) and Magnaporthe oryzae (0·3‐log). Dilution experiments showed that BSMV was rendered noninfectious when diluted to >1/512. Follow‐up large‐scale experiments using up to 400 l of microbiologically contaminated waste water revealed that the filtration of drainage water followed by UV treatment could successfully be used to inactivate several plant pathogens. Conclusions: By combining sedimentation, filtration and UV irradiation within a closed system, plant pathogens can be successfully removed from collected drainage water. Significance and Impact of the Study: Ultraviolet irradiation is a relatively low cost, energy efficient and labour nonintensive method to decontaminate water arising from a suite of higher biological containment level laboratories and plant growth rooms where genetically modified and/or quarantine fungal and viral plant pathogenic organisms are being used for research purposes.

Inhibitory effect of gamma irradiation against Cucumber green mottle mosaic virus

“…So far, only a few studies have investigated the effects of irradiation on plant viruses as a means of viral inactivation. Only UV treatment has been employed to inactivate certain plant viruses including Tomato bushy stunt virus (TBSV), Tobacco necrosis virus (TNV), Cowpea mosaic virus (CPMV), and Barley stripe mosaic virus (BSMV) (Bawden & Kleczkowski 1953;Rae et al 2008;Urban et al 2011). When total UV doses of ≥ 100 mJ/cm 2 were applied, UV-irradiated BSMV did not cause any local lesions in Chenopodium amaranticolor, whereas non-irradiated BSMV produced > 200 local lesions.…”

“…When total UV doses of ≥ 100 mJ/cm 2 were applied, UV-irradiated BSMV did not cause any local lesions in Chenopodium amaranticolor, whereas non-irradiated BSMV produced > 200 local lesions. When the irradiated viral particles were examined by TEM, considerable damage to the viral coat protein was observed together with an increase in the amount of microscopy stain surrounding and penetrating into the virus particles (Urban et al 2011). Another study found that short-wave (254 nm) UV irradiation inactivated CPMV infectivity, inhibited symptoms on inoculated leaves and degraded viral genomic RNA and particles (Rae et al 2008).…”

A guide to the contained use of plant virus infectious clones

“…However, in some cases, dilution alone may serve to render plant viruses noninfectious. For example, >1/512 dilution of Barley stripe mosaic virus inoculum abolishes infectivity of this virus (Urban et al ., ). Screens or filter socks over drains may be used to collect solid material such as plant waste from run‐off water, which can then be autoclaved (Adair and Irwin, ).…”

“…Screens or filter socks over drains may be used to collect solid material such as plant waste from run‐off water, which can then be autoclaved (Adair and Irwin, ). As many facilities house multiple organisms requiring containment, treatment of common aspects such as water must be validated for all contained organisms, not just viruses (Urban et al ., ).…”

Inactivation of tobacco mosaic virus using gamma irradiation and its potential modes of action

“…Th e unit of irradiation dose is the gray (Gy), which is the energy absorbed in J kg -1 of the material. Only UV treatment has been employed so far to inactivate certain plant viruses including tomato bushy stunt virus (BSV), tobacco necrosis virus (TNV), cowpea mosaic virus (CPMV), and barley stripe mosaic virus (BSMV) (4,5). To date, no study has investigated the inactivation of plant viruses by gamma irradiation.…”