Pochonia chlamydosporia (Pc123) is a fungal\ud
parasite of nematode eggs which can colonize endophytically\ud
barley and tomato roots. In this paper we use culturing\ud
as well as quantitative PCR (qPCR) methods and a stable\ud
GFP transformant (Pc123gfp) to analyze the endophytic\ud
behavior of the fungus in tomato roots. WPostprint (published version
Chitosan is a natural polymer with applications in agriculture, which causes plasma membrane permeabilisation and induction of intracellular reactive oxygen species (ROS) in plants. Chitosan has been mostly applied in the phylloplane to control plant diseases and to enhance plant defences, but has also been considered for controlling root pests. However, the effect of chitosan on roots is virtually unknown. In this work, we show that chitosan interfered with auxin homeostasis in Arabidopsis roots, promoting a 2–3 fold accumulation of indole acetic acid (IAA). We observed chitosan dose-dependent alterations of auxin synthesis, transport and signalling in Arabidopsis roots. As a consequence, high doses of chitosan reduce WOX5 expression in the root apical meristem and arrest root growth. Chitosan also propitiates accumulation of salicylic (SA) and jasmonic (JA) acids in Arabidopsis roots by induction of genes involved in their biosynthesis and signalling. In addition, high-dose chitosan irrigation of tomato and barley plants also arrests root development. Tomato root apices treated with chitosan showed isodiametric cells respect to rectangular cells in the controls. We found that chitosan causes strong alterations in root cell morphology. Our results highlight the importance of considering chitosan dose during agronomical applications to the rhizosphere.
Meloidogyne
spp. are the most damaging plant parasitic nematodes for horticultural crops worldwide.
Pochonia chlamydosporia
is a fungal egg parasite of root-knot and cyst nematodes able to colonize the roots of several plant species and shown to induce plant defense mechanisms in fungal-plant interaction studies, and local resistance in fungal-nematode-plant interactions. This work demonstrates the differential ability of two out of five
P. chlamydosporia
isolates, M10.43.21 and M10.55.6, to induce systemic resistance against
M. incognita
in tomato but not in cucumber in split-root experiments. The M10.43.21 isolate reduced infection (32–43%), reproduction (44–59%), and female fecundity (14.7–27.6%), while the isolate M10.55.6 only reduced consistently nematode reproduction (35–47.5%) in the two experiments carried out. The isolate M10.43.21 induced the expression of the salicylic acid pathway (
PR-1
gene) in tomato roots 7 days after being inoculated with the fungal isolate and just after nematode inoculation, and at 7 and 42 days after nematode inoculation too. The jasmonate signaling pathway (
Lox D
gene) was also upregulated at 7 days after nematode inoculation. Thus, some isolates of
P. chlamydosporia
can induce systemic resistance against root-knot nematodes but this is plant species dependent.
SummaryPochonia chlamydosporia has been intensively studied in nematode control of different crops. We have investigated the interaction between P. chlamydosporia and the model system Arabidopsis thaliana under laboratory conditions in the absence of nematodes.This study demonstrates that P. chlamydosporia colonizes A. thaliana. Root colonization monitored with green fluorescent protein-tagged P. chlamydosporia and quantitative PCR (qPCR) quantitation methods revealed root cell invasion. Fungal inoculation reduced flowering time and stimulated plant growth, as determined by total FW increase, faster development of inflorescences and siliques, and a higher yield in terms of seed production per plant.Precocious flowering was associated with significant expression changes in key floweringtime genes. In addition, we also provided molecular and genetic evidence that point towards jasmonate signaling as an important factor to modulate progression of plant colonization by the fungus.Our results indicate that P. chlamydosporia provides benefits to the plant in addition to its nematophagous activity. This report highlights the potential of P. chlamydosporia to improve yield in economically important crops.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.