Effects of earthworm on tomato resistance under different drought levels

Abstract

Aims: Soil invertebrates have the potential to modify plant responses to drought stress. For example, some functional groups improve soil conditions via resource provision and water retention, potentially alleviating drought stress. This study was designed in order to mechanistically understand the functional roles of soil fauna in ecosystem services. Methods: A pot experiment using tomatoes (Lycopersicon esculentum) was conducted in a greenhouse. This study adopted a complete factorial design that manipulated earthworm (Metaphire guillelmi) abundance and drought stress level. Results: Our results indicate that earthworms promote plant drought resistance under high drought stress, which significantly up-regulated gene expression (NCED, NSY, OPR, AOS and LOX) of abscisic acid and jasmonic acid biosynthesis, promoted the accumulation of abscisic acid and jasmonic acid by 43.2% and 33.6%, up-regulated transcription factor expression, and increased the activities of catalase, peroxidase and superoxide dismutase by 12.9%, 8.4% and 47.3% in tomato shoots, respectively. However, under low drought stress, earthworms up-regulated jasmonic acid synthesis pathway gene expression, but reduced abscisic acid content, and had no significant effect on the expression of transcription factors ABF4 and MYC2 genes or plant antioxidant capacity. Conclusion:The effects of earthworms on plant resistance depends on drought level. This study confirms the importance of soil invertebrates in plant drought resistance including the potential impact of earthworms on plant hormone synthesis, signal transduction, and antioxidant capacity.