Developmental, hormone- and stress-modulated expression profiles of four members of the Arabidopsis copper-amine oxidase gene family

Copper-containing amine oxidases (CuAOs) catalyze polyamines (PAs) terminal oxidation producing ammonium, an aminoaldehyde and hydrogen peroxide (H2O2). Plant CuAOs are induced by stress-related hormones, methyl-jasmonate (MeJA), abscisic acid (ABA) and salicylic acid (SA). In the Arabidopsis genome, eight genes encoding CuAOs have been identified. Here, a comprehensive investigation of the expression pattern of four genes encoding AtCuAOs from the α and γ phylogenetic subfamilies, the two peroxisomal AtCuAOα2 (At1g31690) and AtCuAOα3 (At1g31710) and the two apoplastic AtCuAOγ1 (At1g62810) and AtCuAOγ2 (At3g43670), has been carried out by RT-qPCR and promoter::green fluorescent protein-β-glucuronidase fusion (GFP-GUS). Expression in hydathodes of new emerging leaves (AtCuAOγ1 and AtCuAOγ2) and/or cotyledons (AtCuAOα2, AtCuAOγ1 and AtCuAOγ2) as well as in vascular tissues of new emerging leaves and in cortical root cells at the division/elongation transition zone (AtCuAOγ1), columella cells (AtCuAOγ2) or hypocotyl and root (AtCuAOα3) was identified. Quantitative and tissue-specific gene expression analysis performed by RT-qPCR and GUS-staining in 5- and 7-day-old seedlings under stress conditions or after treatments with hormones or PAs, revealed that all four AtCuAOs were induced during dehydration recovery, wounding, treatment with indoleacetic acid (IAA) and putrescine (Put). AtCuAOα2, AtCuAOα3, AtCuAOγ1 and AtCuAOγ2 expression in vascular tissues and hydathodes involved in water supply and/or loss, along with a dehydration-recovery dependent gene expression, would suggest a role in water balance homeostasis. Moreover, occurrence in zones where an auxin maximum has been observed along with an IAA-induced alteration of expression profiles, support a role in tissue maturation and xylem differentiation events

ANALYSIS OF THE DIURNAL EXPRESSION PATTERNS OF THE TOMATO CHLOROPHYLL alb BINDING PROTEIN GENES. INFLUENCE OF LIGHT and CHARACTERIZATION OF THE GENE FAMILY *

Steady-state mRNA levels of the chlorophyll alb binding ( cab ) proteins oscillate substantially during a diurnal cycle in tomato leaves. This accumulation pattern is also observed in complete darkness, supporting the hypothesis that the expression of cab genes is at least partially regulated by an endogenous rhythm (“biological clock”). The amplitude of the cab mRNA accumulation is dependent on the duration of illumination and the circadian phase in which light was applied to the tomato plants. These results at the molecular level correlate well with the photoperiodic phenomenon. The characterization of the expression pattern of individual members of the cab gene family was attempted. Distinct primer extension products were detected using specific oligonucleotides homologous to the cab 1, cab 4, cab 5 and cab 8 genes. Based on this analysis the transcription start sites of these genes were determined to be between position -70 and -9 upstream of the ATG codon. During the diurnal cycle the cab 1 and cab 4 genes exhibit the same expression pattern; no transcripts detected at 3 and 6 a.m., maximum mRNA levels were measured at noon and decreasing levels in the afternoon.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/74852/1/j.1751-1097.1990.tb01752.x.pd

The importance of the urea cycle and its relationships to polyamine metabolism during ammonium stress in Medicago truncatula

The ornithine–urea cycle (urea cycle) makes a signifcant contribution to the metabolic responses of lower photosynthetic eukaryotes to episodes of high nitrogen availability. In this study, we compared the role of the plant urea cycle and its relationships to polyamine metabolism in ammonium-fed and nitrate-fed Medicago truncatula plants. High ammonium resulted in the accumulation of ammonium and pathway intermediates, particularly glutamine, arginine, ornithine, and putrescine. Arginine decarboxylase activity was decreased in roots, suggesting that the ornithine decarboxylase-dependent production of putrescine was important in situations of ammonium stress. The activity of copper amine oxidase, which releases ammonium from putrescine, was signifcantly decreased in both shoots and roots. In addition, physiological concentrations of ammonium inhibited copper amine oxidase activity in in vitro assays, supporting the conclusion that high ammonium accumulation favors putrescine synthesis. Moreover, early supplementation of plants with putrescine avoided ammonium toxicity. The levels of transcripts encoding urea-cyclerelated proteins were increased and transcripts involved in polyamine catabolism were decreased under high ammonium concentrations. We conclude that the urea cycle and associated polyamine metabolism function as important protective mechanisms limiting ammonium toxicity in M. truncatula. These fndings demonstrate the relevance of the urea cycle to polyamine metabolism in higher plants.This work was supported by the grants from the Spanish Government AGL2014-52396-P (MICINN) and AGL2017-86293-P (MINECO/ FEDER) to JFM, and the Basque Government, Spain, IT-1018-16 (UPV/EHU-GV) to RE. MU is a recipient of a pre-doctoral fellowship from the Government of Navarre, Spain. JB and PLG have received pre-doctoral fellowships from the Public University of Navarre, Spain. PT has received funding from the Italian Ministry of Education, University and Research (Grant to Department of Science, University ‘Roma Tre’-‘Dipartimenti di Eccellenza’, ARTICOLO 1, COMMI 314– 337. LEGGE 423 232/2016; PRIN 2017—CUP F84I19000730005). Partial support was obtained from the Spanish State Research Agency AGL2017-83358-R (AEI/FEDER) and the Government of Aragon, Spain, Group A09-20R to YG. Open Access funding was provided by the Public University of Navarra

Antibody-mediated Prevention of Fusarium Mycotoxins in the Field

Fusarium mycotoxins directly accumulated in grains during the infection of wheat and other cereal crops by Fusarium head blight (FHB) pathogens are detrimental to humans and domesticated animals. Prevention of the mycotoxins via the development of FHB-resistant varieties has been a challenge due to the scarcity of natural resistance against FHB pathogens. Various antibodies specific to Fusarium fungi and mycotoxins are widely used in immunoassays and antibody-mediated resistance in planta against Fusarium pathogens has been demonstrated. Antibodies fused to antifungal proteins have been shown to confer a very significantly enhanced Fusarium resistance in transgenic plants. Thus, antibody fusions hold great promise as an effective tool for the prevention of mycotoxin contaminations in cereal grains. This review highlights the utilization of protective antibodies derived from phage display to increase endogenous resistance of wheat to FHB pathogens and consequently to reduce mycotoxins in field. The role played by Fusarium-specific antibody in the resistance is also discussed

The tree of life of polyamine oxidases

Abstract Polyamine oxidases (PAOs) are characterized by a broad variability in catalytic properties and subcellular localization, and impact key cellular processes in diverse organisms. In the present study, a comprehensive phylogenetic analysis was performed to understand the evolution of PAOs across the three domains of life and particularly within eukaryotes. Phylogenetic trees show that PAO-like sequences of bacteria, archaea, and eukaryotes form three distinct clades, with the exception of a few procaryotes that probably acquired a PAO gene through horizontal transfer from a eukaryotic donor. Results strongly support a common origin for archaeal PAO-like proteins and eukaryotic PAOs, as well as a shared origin between PAOs and monoamine oxidases. Within eukaryotes, four main lineages were identified that likely originated from an ancestral eukaryotic PAO before the split of the main superphyla, followed by specific gene losses in each superphylum. Plant PAOs show the highest diversity within eukaryotes and belong to three distinct clades that underwent to multiple events of gene duplication and gene loss. Peptide deletion along the evolution of plant PAOs of Clade I accounted for further diversification of function and subcellular localization. This study provides a reference for future structure–function studies and emphasizes the importance of extending comparisons among PAO subfamilies across multiple eukaryotic superphyla

Immunotherapy of plant viral diseases

The stable expression of antibodies in plants is one recent strategy for the unconventional control of plant viruses that is undergoing development. The advantages of this approach are its wide applicability and intrinsic safety; however, to be successful, the 'genetic immunization' of plants requires careful antibody design, efficient expression and targeting to appropriate cell compartments