Amino acid changes during sunflower infection by the necrotrophic fungusB. cinerea

Abstract

M etabolic changes that occur inhost tissues during a necrotrophic plant/fungal interaction have been poorly investigated. Whereas carbon metabolism reprogramming and photosynthesis disturbances have been studied, 1 data on plant amino acids stores during infection are scarce. Here we report an analysis of sunflower cotyledon amino acid content during infection with the necrotrophic fungus Botrytis cinerea, by using 13 C-NMR spectroscopy. A rapid disappearance of plant amino acids was observed, most probably due to fungal assimilation. In order to explore amino acid changes due to host reaction, we investigated the amino acid content in healthy and invaded region of infected leaves. During the course of infection, glutamate store was affected at distance in the non invaded region. Glutamate depletion was correlated to an enhanced sunflower glutamate dehydrogenase (GDH) transcription level in the area invaded by pathogen. Our data suggest that glutamate could be transferred to the invaded region to supply nitrogen. Such a strategy could delay cell death, and consequently disturb fungal progression in plant tissues.As a necrotrophic fungus, Botrytis cinerea induces host cell death to enable rapid colonization of plants and derive nutrients from sacrificed cells. 2,3 Main pathogenicity factors, toxin and lytic enzyme secretion act synergistically to kill, degrade and macerate host plant tissues. 4 Oxalic acid secretion by Sclerotinia sclerotiorum is now considered as a subtle process to promote plant defence mechanisms that will contribute to host cell death and favor pathogen to progress and feed. 5 We have investigated soluble carbon transfer from host to pathogen using 13 C-NMR spectroscopy during sunflower cotyledon infection by B. cinerea. 6 Plant soluble sugars (glucose, fructose and sucrose) rapidly disappeared and were converted to fungal metabolites (mannitol, trehalose and glycogen), generating a strong carbohydrate capacity. Mannitol pathway plays a central role in B. cinerea carbon metabolism. This pathway allows glucose and fructose conversion into mannitol by independent routes, fructose being essentially converted in mannitol. 6 Soluble carbon metabolite profiling, performed through the course of infection, revealed also the fate of amino acids from plant and fungal origin. Here we present amino acid changes during infection of sunflower cotyledon. PCA extracts obtained from healthy eight-days-old sunflower germlings, infected cotyledons (24, 48, 72, 94 and 120 hpi) and B. cinerea mycelium collected after saprophytic growth, were analyzed by 13 C-NMR spectroscopy (Fig. 1). Glutamine, glutamate, arginine and asparagine (0.7, 0.4, 0.4 and 0.2 mg.g -1 FW) were the main amino acid detected in healthy sunflower cotyledons. In B. cinerea mycelium, the main amino acids detected by NMR spectroscopy were glutamate, glutamine, aspartic acid, arginine and alanine (0.9, 0.4, 0.2, 0.16, 0.08 mg.g -1 FW). In fungal mycelium and cotyledon, glutamate and glutamine were

Common bean varieties demonstrate differential physiological and metabolic responses to the pathogenic fungusSclerotinia sclerotiorum

“…Among the amino acids detected in A195, only asparagine increased in leaf tissue, and all other amino acids did not change or decreased in abundance (Figure a). A decrease in amino acids has been observed in sunflower infected with S. sclerotiorum (Dulermo, Bligny, Gout, & Cotton, ), including asparagine. Asparagine has been associated with plant resistance and/or microbial virulence in pea, pepper, and tomato (Hwang, An, & Hwang, ; Olea et al, ; Z. Yang, Rogers, Song, Guo, & Kolattukudy, ).…”

Transcriptional and Metabolic Changes Associated to the Infection by Fusarium verticillioides in Maize Inbreds with Contrasting Ear Rot Resistance

“…Plant soluble sugars (glucose, fructose and sucrose) could rapidly be metabolized and be converted to fungal metabolites (mannitol, trehalose and glycogen) [42]. Sequestering of host fructose as mannitol, depends on the fact that only a small number of plants have the ability to metabolize mannitol, and the fungus becomes a carbohydrate sink within the host [43].…”

“…Aminoacids could also be consumed during fungal colonization and would act as a nitrogen sink during infection [42]. Decrease in aminoacids levels in kernels of L4674 could be related with the ability of F. verticilliodes to preferentially colonize this line.…”

Elicitor and nitrogen applications to Garnacha, Graciano and Tempranillo vines: effect on grape amino acid composition

“…In Scots pine ( Pinus sylvestris L., Pinaceae) plants, methyl jasmonate induced the synthesis of terpenoid resins; however, growth was decreased significantly with respect to control samples . Thus Dulermo et al . studied the metabolic changes that occur during infection with the necrotrophic fungus Botrytis cinerea on sunflower cotyledon plants, exhibiting a rapid disappearance of amino acids, probably due to fungal assimilation.…”