ABIOTIC ENVIRONMENTAL FACTORS: EFFECTS ON EPIDEMIOLOGY OF PLANT VIRUS INFECTIONS

摘要

In this work we analyzed possible "crosstalk" between negative effect of abiotic environmental stress factors, radioactivity and heavy metals, on plants, and development of virus infection in these hosts. We have been particularly concerned with two main aspects: (ⅰ) virus infection progress in a single plant and (ⅱ) distribution of virus infections in plants at the population level. Here we have demonstrated that abiotic stressors can induce changes in the appearance of virus-specific symptoms on the plants. Following the results of a set of laboratory and small-scale field experiments with two model systems it is clear that chemical contamination of soil may and do favor an enhanced accumulation of viruses in host plants. Sometimes heavy metals invoked more than a 2.5-fold increment in virus content, comparing to virus-infected plants grown in non-polluted soil. The principal moment is that this elevation of virus content has not been temporary; it remained high for long time. Another side of the story was revealed at the population level. We showed that both the abiotic stressors we studied potentially inflicted broader harm from viruses on a given territory. Viruses have been detected in their respective hosts more frequently. As this has been shown for five different viruses isolated from different plant species, and for two different stress factors separately, we suggest it is indeed the case. Our results and comments are summarized in Figure 8. However, it still remains elusive what exactly is happening to the plants (undergoing stresses of abiotic nature), making possible easier/faster/more efficient development, and further spreading of virus infection. Furthermore, more work is needed to determine if there is any influence of radioactivity/chemical pollution on virus vectors which would, in turn, affect plant virus epidemics. Generally, we propose that virus infections behave quite differently when their hosts undergoing additional stresses of abiotic nature. Viruses tend to accumulate to higher levels in plant tissues; virus infections tend to spread more successfully. Speculating, we believe this may pose a significant risk in the context of uncontrollable distribution of these pathogens, proving a need for careful monitoring of virus circulation in (radioactively/chemically) contaminated environments to avoid their spreading to the neighboring agrocenoses.