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Ganoderma produces lignolytic enzymes that can degrade the lignin component of plant cell walls, causing basal stem rot to oil palms. Nitrogen sources may affect plant tolerance to root pathogens while hydrogen peroxide (H2O2), salicylic acid (SA) and jasmonic acid (JA) play important roles in plant defense against pathogens. In this study, we examined the expression of genes encoding manganese peroxidase (MnP) and laccase (Lac) in Ganoderma boninense treated with different nitrogen sources (ammonium nitrate, ammonium sulphate, sodium nitrate and potassium nitrate), JA, SA and H2O2. Transcripts encoding MnP and Lac were cloned from G. boninense. Of the three GbMnP genes, GbMnP_U6011 was up-regulated by all nitrogen sources examined and H2O2 but was down-regulated by JA. The expression of GbMnP_U87 was only up-regulated by JA while GbMnP_35959 was up-regulated by ammonium nitrate but suppressed by sodium nitrate and down-regulated by H2O2. Among the three GbLac genes examined, GbLac_U90667 was up-regulated by ammonium nitrate, JA, SA and H2O2; GbLac_U36023 was up-regulated by JA and H2O2 while GbLac_U30636 was up-regulated by SA but suppressed by ammonium sulphate, sodium nitrate, JA and H2O2. Differential expression of these genes may be required by their different functional roles in G. boninense.

Fungal necrosis and ethylene inducing proteins (NEPs) induce cell death and elicit strong immune responses in many crops. In this study, we report the cloning and characterization of a transcript encoding NEP from Ganoderma boninense which belongs to a family of fungi in Ganodermataceae that cause serious infections of cacao, rubber, tea, coffee and palms. The open reading frame (ORF) encoding NEP inG. boninense(GbNEP) was cloned by 5′and 3’rapid amplification of cDNA ends (RACE) PCR. The transcript abundance of GbNEP increased in fungal culture treated with salicylic acid and jasmonic acid, respectively. The soluble recombinant Gb EP expressed in Escherichia coli BL21(DE3) pLysS was able to induce necrosis in tobacco and tomato but ineffective when applied to oil palm leaves and root tissues. The recombinant GbNEP could induce localized cell death, and production of hydrogen peroxide and superoxide in tobacco leaves. The addition of LaCl3(a calcium channel inhibitor) and EGTA (a Ca2+chelator) to tobacco leaves prior to the challenge with GbNEP significantly reduced the necrosis symptoms indicating that Ca2+is required for the action of GbNEP. In summary, this is the first report of NEP from Ganoderma species which may contribute to further research on the role of GbNEP during disease development.

Basal Stem Rot (BSR) is a serious disease caused by Ganoderma species. Ganoderma boninense produces lignin degrading enzymes (LDEs) that are able to degrade the lignin component of plant cell wall causing oil palms to rot and eventually collapse. The transcripts and expressions of LDEs including manganese peroxidase (MnP) and laccase (Lac) in G. boninense PER71 during oil palm-Ganoderma interaction have not been reported. Likewise, the effect of nitrogen sources in fertilizers, phytohormones and hydrogen peroxide on the growth and gene expression of G. boninense are unknown. Therefore, the objectives of this study were to clone the transcripts encoding these LDEs; to measure their gene expression in G. boninense PER71 treated with different nitrogen sources (ammonium sulphate, ammonium nitrate, sodium nitrate and potassium nitrate), phytohormones (jasmonic acid, JA and salicylic scid, SA) and hydrogen peroxide; and to evaluate the effect of different nitrogen sources on the in vitro growth of G. boninense and oil palm seedlings inoculated with G. boninense. The full-length cDNA of four MnPs and three Lacs were cloned from G. boninense by Rapid Amplification of cDNA Ends (RACE)-PCR and confirmed by sequence analysis. Real-time reverse transcription-PCR (qRT-PCR) analysis showed that only Unigene 6011 (MnP) from G. boninense was upregulated by all nitrogen sources and hydrogen peroxide but down-regulated in JA treatment. Unigene 87 (MnP) showed up-regulation in G. boninense treated with JA. Unigene 35959 (MnP) of G. boninense was up-regulated by ammonium sulphate treatment, down-regulated by hydrogen peroxide and suppressed by sodium nitrate and SA. Meanwhile, Unigene 30636 (Lac) was up-regulated by SA; down-regulated by hydrogen peroxide and suppressed by ammonium sulphate, potassium nitrate and JA. Unigene 36023 (Lac) was up-regulated by JA and hydrogen peroxide while Unigene 90667 (Lac) was up-regulated by ammonium nitrate, JA, SA and hydrogen peroxide. The growth

Herbicides are inevitable inputs to control excessive weed in crop land, particularly where modern agricultural practices such as conservation tillage, are opted. Intensive farming has increased the market value of herbicides among the other pesticides. Although herbicides are effective in controlling weed population, administration of this synthetic chemicals may alter the soil microbial community causing potential increase of plant pathogens. Moreover, herbicides may also have nontarget effects on the cultivated crops making them more susceptible to diseases. Actions of herbicides in soil that either stimulate microbial growth or wipe out some microbial population may create space for the thrivial of opportunistic fungi. Previous studies showed that white rot fungi are more tolerant to herbicides as they produce lignin degrading enzymes that are highly oxidative, non-specific and are able to transform a wide range of herbicides. Besides that, this group of fungi can grow on agricultural waste substrates. Influence of these herbicides on soil microbial ecosystem and interactions of plants and pathogenic white rot fungi modulate disease development in plant hosts.