Salivary DNase II from Laodelphax striatellus acts as an effector that suppresses plant defence

Abstract

Summary Extracellular DNA, released by damaged plant cells, acts as a damage‐associated molecular pattern (DAMP). We demonstrated previously that the small brown planthopper (Laodelphax striatellus, SBPH) secreted DNase II when feeding on artificial diets. However, the function of DNase II in insect feeding remained elusive. The influences of DNase II on SBPHs and rice plants were investigated by suppressing expression of DNase II or by application of heterogeneously expressed DNase II. We demonstrated that DNase II is mainly expressed in the salivary gland and is responsible for DNA‐degrading activity of saliva. Knocking down the expression of DNase II resulted in decreased performance of SBPH reared on rice plants. The dsDNase II‐treated SBPH did not influenced jasmonic acid (JA), salicylic acid (SA), ethylene (ET) pathways, but elicited a higher level of H2O2 and callose accumulation. Application of heterogeneously expressed DNase II in DNase II‐deficient saliva slightly reduced the wound‐induced defence response. We propose a DNase II‐based invading model for SBPH feeding on host plants, and provide a potential target for pest management.

Herbivore‐specific plant volatiles prime neighboring plants for nonspecific defense responses

“…Therefore, this difference in volatile emissions could also, in part, be explained by the amount and type of salivary secretions and degraded plant molecules deposited on the feeding site. Some herbivore salivary secretions elicit defenses, while others suppress it (Huang et al, ; Tian et al, ). Similarly, extracellular plant molecules released or deposited at the wounded site act as damage‐associated molecular patterns (DAMPs) and could differentially trigger defense responses (Duran‐Flores & Heil, , ).…”

Current understanding of the molecular players involved in resistance to rice planthoppers

“…Present data show that some BPH salivary proteins function as effectors. These include an endo‐ β ‐1,4‐glucanase, salivary DNase II and salivary EF‐hand calcium‐binding protein, which all inhibit the rice defense response to planthoppers. Conversely, some salivary proteins function as elicitors, such as the BPH‐secreted mucin‐like protein, which induces rice defense response against planthoppers.…”

“…The BPH secreted salivary DNase II participates in extracellular DNA degradation. By degrading the released DNA fragments in rice, the BPH secreted salivary DNase II prevents the intact cells of rice from detecting the ‘wound signal’ and thus suppress the rice plant's defense . Calcium ions (Ca 2+ ) influx in rice can induce occlusion of rice phloem to prevent insect feeding.…”

“…By degrading the released DNA fragments in rice, the BPH secreted salivary DNase II prevents the intact cells of rice from detecting the 'wound signal' and thus suppress the rice plant's defense. 12 Calcium ions (Ca 2+ ) influx in rice can induce occlusion of rice phloem to prevent insect feeding. Some salivary proteins are able to sequester Ca 2+ ions in rice and thereby prevent rice phloem from plugging.…”

Plant immunity and sustainable control of pests in China: Advances, opportunities and challenges

“…. 南京农业大学团队发现, 灰飞虱唾 液中的DNase Ⅱ抑制植物胼胝质形成和过氧化氢积 累 [251] . 这些研究揭示了植物与昆虫互作的分子机制, 为农作物抗虫育种提供了重要理论依据与新颖的 思路.…”