Identification of metabolic pathways influenced by the G-protein coupled receptors GprB and GprD in Aspergillus nidulans

Heterotrimeric G-protein-mediated signaling pathways play a pivotal role in transmembrane signaling in eukaryotes. Our main aim was to identify signaling pathways regulated by A. nidulans GprB and GprD G-protein coupled receptors (GPCRs). When these two null mutant strains were compared to the wild-type strain, the DeltagprB mutant showed an increased protein kinase A (PKA) activity while growing in glucose 1% and during starvation. In contrast, the DeltagprD has a much lower PKA activity upon starvation. Transcriptomics and (1)H NMR-based metabolomics were performed on two single null mutants grown on glucose. We noted modulation in the expression of 11 secondary metabolism gene clusters when the DeltagprB and DeltagprD mutant strains were grown in 1% glucose. Several members of the sterigmatocystin-aflatoxin gene cluster presented down-regulation in both mutant strains. The genes of the NR-PKS monodictyphenone biosynthesis cluster had overall increased mRNA accumulation in DeltagprB, while in the DeltagprD mutant strain the genes had decreased mRNA accumulation. Principal component analysis of the metabolomic data demonstrated that there was a significant metabolite shift in the DeltagprD strain. The (1)H NMR analysis revealed significant expression of essential amino acids with elevated levels in the DeltagprD strain, compared to the wild-type and DeltagprB strains. With the results, we demonstrated the differential expression of a variety of genes related mainly to secondary metabolism, sexual development, stress signaling, and amino acid metabolism. We propose that the absence of GPCRs triggered stress responses at the genetic level. The data suggested an intimate relationship among different G-protein coupled receptors, fine-tune regulation of secondary and amino acid metabolisms, and fungal development

Analysis of polarity establishment during megagametogenesis and early zygotic embryogenesis in Zea mays

Asymmetric cell division is one of the mechanisms to generate cellular diversity in multicellular organisms including flowering plants. Two major pathways have been reported by which plants perform asymmetric cell division, namely, (i) the “one mother-two different daughters” and (ii) the “coenocytes-cellularization” pathway. In the “one mother-two different daughters” pathway, a mother cell divides to generate two daughter cells which are either different in size and fate or which are initially comparable in size but subsequently get different fates (Ranganath, 2007). This pathway is exemplified by the asymmetric division of the zygote in maize, giving rise to the small apical cell and the large basal cell. Microarray hybridizations were performed comparing the egg cell, the apical cell and the basal cell to identify candidate transcripts that are polarly localized in the egg cell and which segregated either to the apical or basal cell of the two-celled proembryo after zygotic division. Several interesting candidate genes were identified to be expressed in the maize egg cell and differentially expressed in the apical or basal cell. The majority of differentially expressed genes encode for proteins involved in gene regulation, metabolism and proteins with unknown function. Furthermore, other classes of transcripts encode for proteins involved in signaling, vesicle trafficking, cytoskeleton, RNA metabolism, protein/protein interaction, cell wall biogenesis/structure, transport, targeting proteins for degradation and protein folding. The “coenocytes-cellularization” pathway is based on the formation of a coenocyte, involving nuclear migration to specific locations and cellularization, which occurs during megagametogenesis in maize. The role of two proteins, namely, ZmEAL1 (Zea mays EA1 Like1) and ZmDSUL (Zea mays DiSUMO-Like), was analyzed during female gametophyte development. ZmEAL1 is a small secreted peptide expressed specifically in the egg cell in the embryo sac. After fertilization, ZmEAL1 is expressed in the embryo proper until seven days after pollination. ZmEAL1 is involved in cell fate maintenance during female gametophyte development. On the other hand, ZmDSUL transcripts were detected exclusively in the egg apparatus and zygote of maize. ZmDSUL appears to be essential for nuclei segregation and positioning, the prerequisite for cell specification during FG maturation

A enxertia na cultura do maracujazeiro: aspectos anatômicos, bioquímicos e fisiológicos

Due to the expansion of orchards, problems with soil pathogens are frequent and cause injury and/or make passion fruit cultivation impossible in Brazil. Thus, studies with potential species for rootstocks become indispensable to assist in the technological development of the culture. It is necessary to take into account several aspects of grafting, for the adoption of appropriate techniques, among them we can highlight the anatomy, physiology and also biochemistry. This study aimed to review the existing papers related to grafting of passion fruit and also to understand the operation of grafting itself. It was observed that several publications are related to the topic of the present review and that grafting is a viable alternative to the cultivation of passion fruit, however additional studies about grafting and production are needed.Por conta da expansão dos pomares, problemas com patógenos de solo são frequentes e causam prejuízos e/ou inviabilizam a cultura do maracujá no Brasil. Assim, estudos com espécies potenciais para porta-enxertos se tornam imprescindíveis para auxiliar no desenvolvimento tecnológico dessa cultura. Para a adoção de técnicas adequadas faz-se necessário levar em consideração diversos aspectos da enxertia, dentre eles podemos destacar a anatomia, a fisiologia e, também, a bioquímica. O presente trabalho teve como objetivo fazer uma revisão dos trabalhos existentes relacionados à enxertia de maracujazeiros e, também, entender o funcionamento da enxertia, propriamente dita. Observou-se a existência de grande numero de pesquisas relacionadas ao tema e que, a enxertia se apresenta como alternativa viável ao cultivo de maracujá, sendo necessários novos estudos relacionando enxertia e produção

Germinação de sementes de maracujazeiros: água, luz, temperatura e reguladores vegetais

The production of seedlings of passion fruit is done mainly with the use of seeds by most producers. It can also be propagated by cuttings, layering and in vitro tissue culture. However, even when grafting is used, it is necessary to use seeds to produce the rootstock. Nevertheless, most Passifloracea species have germination problems, making it difficult to obtain seedlings. Although several studies have been developed in an attempt to increase seed germination of passion fruit there are still difficulties in understanding the germination process and also disagreement about seed dormancy. Thus, the present study aimed to review papers related to seed germination of passion fruit emphasizing aspects such as mechanical resistance to water ingress, the need for adequate light and temperature and the use of plant growth regulators in overcoming seed dormancy. It was noticed that, in general, the passion fruit seeds are photoblastic negative and exhibit physiological dormancy, being no need of seed scarification to stimulate its germination.A produção de mudas de maracujá é feita principalmente com o uso de sementes pela grande maioria dos produtores. Também pode ser propagado por estaquia, alporquia e cultura de tecidos in vitro. Porém, mesmo quando utilizado a enxertia, faz-se necessário o uso de sementes para a produção do porta enxerto. No entanto, a maioria das Passifloráceas apresentam problemas de germinação, o que dificulta a obtenção de mudas. Embora diversos estudos tenham sido desenvolvidos na tentativa de aumentar a germinação das sementes de maracujazeiros ainda há dificuldades na compreensão do processo germinativo e, também, divergências quanto à causa da dormência. Assim, o presente trabalho teve como objetivo fazer um levantamento dos estudos relacionados à germinação de sementes de maracujazeiros enfatizando alguns aspectos como a resistência à entrada de água, a necessidade de luz e temperatura adequadas e o uso de reguladores vegetais na superação da dormência. Observou-se que, de maneira geral, as sementes são fotoblásticas negativas e apresentam dormência do tipo fisiológica, não sendo necessária a escarificação das sementes para a germinação das mesmas

Sub-cellular location of GprB and–D.

<p>(A) GprB::GFP, (B) GprD::mRFP (grown in MM+0% glucose), (C) GprD::mRFP (grown in MM+0.1% glucose), and (D) GprD::mRFP (grown in MM+1.0% glucose) at 30°C (Bars, 10 µm).</p

The metabolome of <i>A. nidulans ΔgprB</i> and <i>ΔgprB</i> strains grown on glucose.

<p>(A) PCA plot illustrating the variance of the integrals from NMR spectral data for all strains collected at 24 or 48 hours. (B–D) Column charts for identified metabolites expressed in Relative Metabolite Levels (Calculated taking Log2 of molar ratios from integrated spectral data). Metabolite levels were measured and averaged for each strain after 24 hours of growth (<i>black</i>) and 48 hours of growth (<i>light grey</i>). Using a two-way ANOVA, at 24 hours P<0.001 was determined for leucine/isoleucine, valine, isoleucine, β-hydroxybutyrate, acetate, malate, and aspartate, P<0.05 was determined for glucose. At 48 hours, P<0.001 was determined for valine and glucose, P<0.01 was determined for isoleucine and lactate, P<0.05 was determined for leucine/isoleucine and β-hydroxybutyrate. The columns not sharing the same letter are significantly different from strains within their time of collection (Tukey HSD, <i>p</i><0.05).</p