Open AccessArtificial induction of third-stage dispersal juveniles of Bursaphelenchus xylophilus using newly established inbred lines
Author(s) -
Shino Tanaka,
Takuya Aikawa,
Yuko Takeuchi-Kaneko,
Kenji Fukuda,
Natsumi Kanzaki
Publication year - 2017
Publication title -
plos one
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.99
H-Index - 332
ISSN - 1932-6203
DOI - 10.1371/journal.pone.0187127
Subject(s) - bursaphelenchus xylophilus , biological dispersal , biology , nematode , juvenile , population , monochamus alternatus , inbred strain , zoology , botany , wilt disease , host (biology) , colonization , ecology , genetics , gene , longhorn beetle , medicine , environmental health
The pine wood nematode, Bursaphelenchus xylophilus , is the causal agent of pine wilt disease. This nematode has two developmental forms in its life cycle; i.e., the propagative and dispersal forms. The former is the form that builds up its population inside the host pine. The latter is specialized for transport by the vector. This form is separated into two dispersal stages (third and fourth); the third-stage dispersal juvenile (J III ) is specialized for survival under unfavorable conditions, whereas the fourth-stage juvenile (J IV ), which is induced by a chemical signal from the carrier Monochamus beetle, is transported to new host pines and invades them. Because of its importance in the disease cycle, molecular and chemical aspects of the J IV have been investigated, while the mechanism of J III induction has not been sufficiently investigated. In an effort to clarify the J III induction process, we established inbred lines of B . xylophilus and compared their biological features. We found that the total number of nematodes (propagation proportion) was negatively correlated with the J III emergence proportion, likely because nematode development was arrested at J III ; i.e., they could not develop to adults via the reproductive stage. In addition, J III induction seemed to be regulated by a small number of genes because the J III induction proportion varied among inbred lines despite the high homozygosity of the parental line. We also demonstrated that J III can be artificially induced by the nematode’s secreted substances. This is the first report of artificial induction of J III in B . xylophilus . The dauer (dispersal) juvenile of the model organism Caenorhabditis elegans corresponds functionally to J III of B . xylophilus , and this stage is known to be induced by a chemical signal referred to as daumone, derived from the nematodes’ secretion. The artificial induction of J III suggests the presence of daumone-like material in B . xylophilus .