Virus-induced deterrence to aphid feeding is believed to promote plant virus transmission by encouraging migration of virus-bearing insects away from infected plants. We investigated the effects of infection by an aphid-transmitted virus, cucumber mosaic virus (CMV), on the interaction of Arabidopsis thaliana, one of the natural hosts for CMV, with Myzus persicae (common names: ‘peach-potato aphid’, ‘green peach aphid’). Infection of Arabidopsis (ecotype Col-0) with CMV strain Fny (Fny-CMV) induced biosynthesis of the aphid feeding-deterrent 4-methoxy-indol-3-yl-methylglucosinolate (4MI3M). 4MI3M inhibited phloem ingestion by aphids and consequently discouraged aphid settling. The CMV 2b protein is a suppressor of antiviral RNA silencing, which has previously been implicated in altering plant-aphid interactions. Its presence in infected hosts enhances the accumulation of CMV and the other four viral proteins. Another viral gene product, the 2a protein (an RNA-dependent RNA polymerase), triggers defensive signaling, leading to increased 4MI3M accumulation. The 2b protein can inhibit ARGONAUTE1 (AGO1), a host factor that both positively-regulates 4MI3M biosynthesis and negatively-regulates accumulation of substance(s) toxic to aphids. However, the 1a replicase protein moderated 2b-mediated inhibition of AGO1, ensuring that aphids were deterred from feeding but not poisoned. The LS strain of CMV did not induce feeding deterrence in Arabidopsis ecotype Col-0. Inhibition of AGO1 by the 2b protein could act as a booby trap since this will trigger antibiosis against aphids. However, for Fny-CMV the interplay of three viral proteins (1a, 2a and 2b) appears to balance the need of the virus to inhibit antiviral silencing, while inducing a mild resistance (antixenosis) that is thought to promote transmission. The strain-specific effects of CMV on Arabidopsis-aphid interactions, and differences between the effects of Fny-CMV on this plant and those seen previously in tobacco (inhibition of resistance to aphids) may have important epidemiological consequences.

This study aimed to isolate and identify bacteria that can produce amylase enzyme from the unexplored Nasinuan Forest, Kantarawichai District, Mahasarakham Province, Thailand. Thirteen bacterial isolates with amylase-producing capacity on 1% starch agar were identified using 16S rRNA sequencing. Twelve bacteria were gram-positive, rod shaped and identified as Bacillus spp. and one bacterium with gram-negative and rod shaped character was Enterobacter cloacae. Their closest relatives were found in India, China, Korea, Indonesia, Argentina, Italy, Israel, USA, Argentina and South Africa. These bacteria were tested for specific amylase activity after 1-3 days enzyme induction with 1% starch at 37°C. The results showed the highest specific activity at day 2 incubation in the order: Bacillus cereus 3.5AL2 > 3.4AL1 > 1.4AL3 and thus 2-day enzyme induction was chosen for further analysis. Bacillus sp. 3.5AL2 was found to exhibit the highest specific amylase enzyme activity of 1.97 ± 0.41 U/mg protein at the optimal conditions of 60°C and pH 7.0 after 30 min incubation with 1% starch in 0.05 M PBS buffer. This amylase–producing bacterial strain offers great potential for applications in food and agricultural industries in Thailand.

Food Science of Animal Resources (Food Sci. Anim. Resour.) is an international, peer-reviewed bimonthly journal publishing original research and reviews on basic and applied aspects of the use of animal resources including the meat, egg, dairy, and edible insect/worm products. Food Sci. Anim. Resour. is published and distributed by the Korean Society for Food Science of Animal Resources.