Black pepper (Piper nigrum L.), a tropical spice crop of global acclaim, is susceptible to Phytophthora capsici, an oomycete pathogen which causes the highly destructive foot rot disease. A systematic understanding of this phytopathosystem has not been possible owing to lack of genome or proteome information. In this study, we explain an integrated transcriptome-assisted label-free quantitative proteomics pipeline to study the basal immune components of black pepper when challenged with P. capsici. We report a global identification of 532 novel leaf proteins from black pepper, of which 518 proteins were functionally annotated using BLAST2GO tool. A label-free quantitation of the protein datasets revealed 194 proteins common to diseased and control protein datasets of which 22 proteins showed significant up-regulation and 134 showed significant down-regulation. Ninety-three proteins were identified exclusively on P. capsici infected leaf tissues and 245 were expressed only in mock (control) infected samples. In-depth analysis of our data gives novel insights into the regulatory pathways of black pepper which are compromised during the infection. Differential down-regulation was observed in a number of critical pathways like carbon fixation in photosynthetic organism, cyano-amino acid metabolism, fructose, and mannose metabolism, glutathione metabolism, and phenylpropanoid biosynthesis. The proteomics results were validated with real-time qRT-PCR analysis. We were also able to identify the complete coding sequences for all the proteins of which few selected genes were cloned and sequence characterized for further confirmation. Our study is the first report of a quantitative proteomics dataset in black pepper which provides convincing evidence on the effectiveness of a transcriptome-based label-free proteomics approach for elucidating the host response to biotic stress in a non-model spice crop like P. nigrum, for which genome information is unavailable. Our dataset will serve as a useful resource for future studies in this plant. Data are available via ProteomeXchange with identifier PXD003887.
SUMMARYNutmeg (Myristica fragrans Houtt.) is an evergreen tree and popular spice. In the present study, Random Amplified Polymorphic DNA (RAPD) analysis was performed to assess the genetic diversity among the 19 superior accessions of nutmeg collected from different geographic locations and maintained in the germplasm collections of Regional Agricultural Research Station, Kumarakom, Kerala. This included one released variety IISR Viswasree. Out of 28 RAPD primers tested, 20 were amplified. Out of the 109 loci amplified, 82 were polymorphic with an average polymorphism rate of 72.74 per cent. The number of bands for each primer ranged from 2 to 8. The markers which produced maximum number of polymorphic bands were BB-18 and PO-5. PIC value of the markers ranging from 0.09 (OPA 11) to 0.48 (W-15) with an average of 0.31. The marker index (MI) varied between 0.09 and 2.08 with an average of 1.25. Jaccard's similarity coefficient of the genotypes ranged between 0.34 -0.93. Dendrogram constructed based on UPGMA analysis grouped the 19 selected genotypes into two major clusters. The knowledge on genetic diversity of nutmeg can be used for further breeding programmes for getting higher nut and mace yield.
<p class="Default"><em>Trichoderma</em> spp. are long been recognized as efficient fungal biocontrol agents for the control of plant disease and for their ability to increase plant growth and development. Management of soil borne diseases has become very much important since it causes high crop yield losses. The present study was carried out to isolate <em>Trichoderma</em> spp. from soil samples collected from different locations of Kerala and to test their in vitro efficacy against soil borne pathogens viz., <em>Pythium aphanidermatum</em> and <em>Rhizoctonia solani</em>. The <em>Trichoderma</em> spp. was isolated on Trichoderma Selective Medium (TSM) and observed that the isolates differed in radial growth and colony characters such as colony colour, texture and sporulation. In vitro studies revealed the potential of <em>Trichoderma</em> isolates against soil borne pathogens. Isolates TRPN3 and TRPN7 exhibited no sporulation and white mycelial colour. Isolates which completed their growth at four days after inoculation include TRKR1, TRPN3, TRPN7, TRPN10 and TRPN18. Biocontrol activities against different pathogens resulted in inhibition of pathogens. Maximum inhibition percentage was observed by the isolates TRPN7, TRPN15 and TRKR2 against both the pathogens. The maximum inhibition exhibited against both the pathogens is due to the antagonistic property displayed by the isolates.</p>
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