PDF(Pubmed)
Abstract：
Food security has become one of the greatest challenges of the millennium and it is predicted to be exacerbated by climate change due to the adverse effects of soil temperature on crop productivity. Although plant-parasitic nematodes are one of the most important limiting factors of agricultural production, the fate of soil temperature in their biology is not fully understood. Here we present the effects of soil temperature on survival, reproduction, virulence, and disease severity from the perspective of two nematode species Rotylenchulus reniformis and Meloidogyne floridensis. The two nematode species were purposefully selected to represent a significant threat to annual and perennial crops. We employed novel approaches of direct as well as indirect heat exposure to evaluate nematode biology. The direct heat exposure assay involved the exposure of nematodes to hot water in a heating block at 32, 33, and 34 °C for 7 h, and subsequent evaluation of their survival after 18 h. The indirect exposure assay employed a commercial heat mat to raise soil temperatures to 32, 33, and 34 °C for 7 h during the daytime, and subsequent evaluation of nematode reproduction, virulence, and/or disease severity over the period of 6 weeks after inoculation. When directly exposed to hot water at 34 °C, the survival of R. reniformis increased by 10% while the survival of M. floridensis decreased by 12% relative to that at 32 °C. Upon increasing soil temperatures from 32 to 34 °C, the reproduction of R. reniformis and M. floridensis decreased by 49% and 53%, respectively. A significant reduction in the reproduction of M. floridensis occurred when soil temperature was increased from 33 to 34 °C, however, the same condition did not significantly affect R. reniformis reproduction suggesting the latter species has a greater ability to adapt to increasing soil temperature. Additionally, the virulence of R. reniformis was greater at 33 and 34 °C relative to that at 30 °C indicating increased aggressiveness of the nematode at higher soil temperatures. The virulence of M. floridensis appeared to be decreased as evident from increased root biomass when soil temperature was increased from 32 to 34 °C, however, the greater root biomass may have resulted from increased root galling at the higher temperatures. Results of the current study suggest that while higher soil temperatures due to climate change may lead to reduced nematode reproduction, crop losses will likely increase due to increased nematode virulence. Through the current study, we report practical evidence of the quantitative impact of climate change on the biology of plant-parasitic nematodes. Further studies involving a wider range of temperature and exposure time are needed to better understand nematode biology under climate change.
摘要：
粮食安全已成为千年的最大挑战之一，由于土壤温度对作物生产力的不利影响，气候变化预计将加剧粮食安全。虽然植物寄生线虫是农业生产的重要限制因素之一,土壤温度在其生物学中的命运尚未完全了解。这里我们介绍了土壤温度对生存的影响，繁殖，毒力,从两种线虫的角度来看，以及疾病的严重程度。有目的地选择这两种线虫物种，以对一年生和多年生作物构成重大威胁。我们采用了直接和间接热暴露的新方法来评估线虫生物学。直接热暴露测定涉及线虫在32、33和34°C的加热块中暴露于热水中7小时，并在18小时后对其存活率进行后续评估。间接暴露试验采用商业加热垫在白天将土壤温度提高到32、33和34°C，持续7小时，以及随后对线虫繁殖的评估，毒力,和/或接种后6周期间的疾病严重程度。当直接暴露在34°C的热水中时，与32°C相比，肾形R.的存活率增加了10％，而Floridensis的存活率降低了12％。当土壤温度从32°C升高到34°C时，肾形R.Floridensis和M.Floridensis的繁殖减少了49％和53％，分别。当土壤温度从33°C升高到34°C时，Floridensis的繁殖显着减少，然而,相同的条件并未显着影响R.reniformis的繁殖，表明后者具有更大的适应土壤温度升高的能力。此外,与30°C相比，肾形R.reniformis在33和34°C的毒力更大，表明在较高的土壤温度下线虫的侵袭性增加。当土壤温度从32°C升高到34°C时，从根部生物量的增加可以明显看出，花草菌的毒力似乎降低了。然而,较高的根生物量可能是由于在较高温度下根的磨损增加所致。目前的研究结果表明，虽然由于气候变化导致的土壤温度升高可能导致线虫繁殖减少，由于线虫毒力的增加，作物损失可能会增加。通过目前的研究,我们报告了气候变化对植物寄生线虫生物学的定量影响的实际证据。需要进行更广泛的温度和暴露时间范围的进一步研究，以更好地了解气候变化下的线虫生物学。
