Differentially Accumulated Proteins in Coffea arabica Seeds during Perisperm Tissue Development and Their Relationship to Coffee Grain Size

Coffee is one of the most important crops for developing countries. Coffee classification for trading is related to several factors, including grain size. Larger grains have higher market value then smaller ones. Coffee grain size is determined by the development of the perisperm, a transient tissue with a higly active metabolism, which is replaced by the endosperm during seed development. In this study, a proteomics approach was used to identify differentially accumulated proteins during perisperm development in two genotypes with regular (IPR59) and large grain sizes (IPR59-Graudo) in three developmental stages. Twenty-four spots were identified by MALDI-TOF/TOF-MS, corresponding to 15 proteins. We grouped them into categories as follows: storage (11S), methionine metabolism, cell division and elongation, metabolic processes (mainly redox), and energy. Our data enabled us to show that perisperm metabolism in IPR59 occurs at a higher rate than in IPR59-Graudo, which is supported by the accumulation of energy and detoxification-related proteins. We hypothesized that grain and fruit size divergences between the two coffee genotypes may be due to the comparatively earlier triggering of seed development processes in IPR59. We also demonstrated for the first time that the 11S protein is accumulated in the coffee perisperm

Label-Free Quantitative Proteomic Analysis of <i>Puccinia psidii</i> Uredospores Reveals Differences of Fungal Populations Infecting Eucalyptus and Guava

<div><p><i>Puccinia psidii</i> sensu lato (s.l.) is the causal agent of eucalyptus and guava rust, but it also attacks a wide range of plant species from the myrtle family, resulting in a significant genetic and physiological variability among populations accessed from different hosts. The uredospores are crucial to <i>P</i>. <i>psidii</i> dissemination in the field. Although they are important for the fungal pathogenesis, their molecular characterization has been poorly studied. In this work, we report the first in-depth proteomic analysis of <i>P</i>. <i>psidii</i> s.l. uredospores from two contrasting populations: guava fruits (PpGuava) and eucalyptus leaves (PpEucalyptus). NanoUPLC-MS^E was used to generate peptide spectra that were matched to the UniProt <i>Puccinia</i> genera sequences (UniProt database) resulting in the first proteomic analysis of the phytopathogenic fungus <i>P</i>. <i>psidii</i>. Three hundred and fourty proteins were detected and quantified using Label free proteomics. A significant number of unique proteins were found for each sample, others were significantly more or less abundant, according to the fungal populations. In PpGuava population, many proteins correlated with fungal virulence, such as malate dehydrogenase, proteossomes subunits, enolases and others were increased. On the other hand, PpEucalyptus proteins involved in biogenesis, protein folding and translocation were increased, supporting the physiological variability of the fungal populations according to their protein reservoirs and specific host interaction strategies.</p></div

Proteins identified from <i>P</i>. <i>psidii</i> uredospore populations.

<p>The proteins exclusively found in PpGuava (right) and PpEucalyptus (left) and common to both populations (center). Of the common proteins, 25 and 120 whose abundance were increased in PpEucalyptus and PpGuava, respectively.</p

Gene ontology of biological process terms in the proteomic analysis.

<p>Bar graph represents the ratio of % composition of term in the proteomic data.</p

Morphological and viability analysis of <i>Puccinia psidii</i> uredospores.

<p><i>P</i>. <i>psidii</i> uredospores from <i>E</i>. <i>grandis</i><b>(A)</b> and <i>P</i>. <i>guajava</i><b>(B)</b> exhibit similar morphology and germination viability, respectively <b>(C and D)</b>.The arrows indicate the fungal germ tube in both uredospore populations, 24 hours after inoculation in water-agar medium. Light microscopy images of PpEucalyptus and PpGuava uredospores are shown at 100 X (A and B) and 200 X (C and D) magnification. Scale bar: 20 μm in A and B, 50 μm in C and D.</p

Eucalyptus infection by guava and eucalyptus rust.

<p>Symptoms induced by inoculation of <i>P</i>. <i>psidii</i> uredospores from PpEucalyptus <b>(A)</b> on <i>E</i>. <i>grandis</i> variety D901. This clone is rust susceptible when grown under field conditions. The white arrows indicate the fungal pustules. The leaves are shown 15 days after inoculation.The PpGuava populations <b>(B)</b> and control <b>(C)</b> did not show typical rust symptoms.</p

Protein profiles in PpGuava and PpEucalyptus and the correlation with their physiological variability.

<p>While proteins correlated to fungal virulence and stress response had the abundance increased in PpGuava, proteins related to biogenesis, protein folding and translation had the abundance increased in PpEucalyptus.</p