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Maintenance of ion homeostasis in plant cells is an essential physiological requirement for sustainable growth, development, and yield of crops. Plants respond to high levels of heavy metals such as copper (Cu) and cadmium (Cd) to avoid irreversible damage at the structural, physiological and molecular levels. Our previous study found that rice germin-like proteins (OsGLPs) are a type of Cu-responsive proteins. The deletion of 10 tandem OsGLP genes on chromosome 8 led to more severe heavy metal toxicity in rice. In this study, we show that rice WRKY transcription factor OsWRKY72 negatively regulates OsGLP8-7 transcription. Overexpression of OsWRKY72 weakens the Cu/Cd tolerance of rice when exposed to Cu and Cd. OsWRKY72 suppressed expression of OsGLP8-7 and lignin synthesis genes, resulting in reduced lignin polymerization and consequently lower lignin accumulation in cell walls, thereby increasing the Cu and Cd accumulation. In addition, OsWRKY53 bound to OsWRKY72 to alleviate the transcriptional inhibition of OsGLP8-7. These results revealed that OsWRKY72-OsGLP8-7 is an important module response of rice to heavy metal stress, and that transcription factor OsWRKY72 acts upstream of OsGLP8-7 to regulate Cu/Cd toxicity.

Germin-like proteins (GLPs) play crucial roles in disease resistance, stress tolerance, and plant defense responses in various crop species. This review explores the intricate role of GLP gene expression and its modulation by cis-acting regulatory elements (CAREs) under biotic and abiotic stress in major crops. In rice, OsGLP2-1 and OsGLP3-7 have been identified as positive regulators of disease resistance. Similarly, TaGLP genes in wheat and VvGLP3 in grapes have been associated with powdery mildew resistance. Additionally, ZmGLP1 in maize and StGLP5 in potato contribute to defense against Bipolaris maydis and salt stress, respectively. AhGLPs in peanuts respond to drought stress, while GmGLP10 in soybean demonstrates a response to Sclerotinia sclerotiorum infection. Research in cotton has unveiled GhABP19 and GhGLP2 as GLPs involved in plant defense responses to wilt disease. Analysis of GLP gene promoters has revealed the presence of stress-responsive CAREs that modulate gene expression under biotic and abiotic stresses. Transgenic overexpression of GLP genes in different plant species, such as potato, tobacco, and Arabidopsis, has resulted in enhanced resistance to fungal pathogens, oxidative stress, and abiotic stresses. CRISPR/Cas9 genome editing has provided insights into UV-B stress response mechanisms. Promising outcomes from transgenic studies and CRISPR genome editing present exciting opportunities to improve disease resistance and stress tolerance in crops. These findings significantly enhance our understanding of the critical roles played by GLPs in crop resilience, paving the way for the development of stress-resistant crops to ensure sustainable global food security. [ABSTRACT FROM AUTHOR]

DNA methylation at cytosine residues governs the regulation of stress responsive genes in plant for self-protection against various environmental abiotic stresses. Here, we analyzed the epigenetic consequences of drought and salinity on cytosine methylation dynamics of promoter regions of stress responsive Germin-like protein genes in rice (Oryza sativa). The bisulfite sequencing technique was employed to identify differential methylation status at cytosine residues in selected promoter regions of three OsGLP genes (OsGLP4-1, OsGLP8-10 and OsGLP8-12) in leaves and roots of two elite Indica rice cultivars (tolerant KS282 and sensitive Super Basmati) under drought and salt stress. Our results identified cultivar, tissue and stress-dependent differentially methylated cytosine residues, however, the extent of methylation was found to be different depending upon CGN, CHG and CHH sequence contexts. Among all three OsGLP genes, the promoter region of OsGLP8-12 was detected with the most heavily methylated and significantly differential methylated sites depending upon types of variety, tissue or stress conditions. However, no methylated site was detected in the promoter region of OsGLP4-1. Moreover, in the promoter regions of OsGLP8-10 and OsGLP8-12, several differentially methylated sites in response to stress treatments were identified either near or within cis-regulatory elements (CREs) related to abiotic stress. This indicated the association between methylation in the promoter regions and regulation of OsGLP genes which might be a key mechanism associated with their regulation under abiotic stresses in contrasting rice cultivars. [ABSTRACT FROM AUTHOR]

Copper (Cu) and cadmium (Cd) are common heavy metal pollutants. When Cd and excessive Cu accumulate in plants, plant growth is reduced. Our previous study showed that Germin-like proteins (GLPs), which exist in tandem on chromosomes, are a class of soluble glycoproteins that respond to Cu stress. In this study, hydroponic cultures were carried out to investigate the effect of GLP on Cd and Cu tolerance and accumulation in rice. The results showed that knockout of a single OsGLP8-2 gene or ten OsGLP genes (OsGLP8-2 to OsGLP8-11) resulted in a similar sensitivity to Cd and Cu toxicity. When subjected to Cu and Cd stress, the glp8-2 and glp8-(2-11) mutants displayed a more sensitive phenotype based on the plant height, root length, and dry biomass of the rice seedlings. Correspondingly, Cu and Cd concentrations in the glp8-2 and glp8-(2-11) mutants were significantly higher than those in the wild-type (WT) and OsGLP8-2-overexpressing line. However, Cu and Cd accumulation in the cell wall was the opposite. Furthermore, we determined lignin accumulation. The overexpressing-OsGLP8-2 line had a higher lignin accumulation in the shoot and root cell walls than those of the WT, glp8-2, and glp8-(2-11). The expression of lignin synthesis genes in the OsGLP8-2-overexpressing line was significantly higher than that in the WT, glp8-2, and glp8-(2-11). The SOD activity of OsGLP8-2, Diaminobe-nzidine (DAB), propidium iodide (PI) staining, and Malondialdehyde (MDA) content determination suggested that OsGLP8-2 is involved in heavy metal-induced antioxidant defense in rice. Our findings clearly suggest that OsGLPs participate in responses to heavy metal stress by lignin deposition and antioxidant defense capacity in rice, and OsGLP8-2 may play a major role in the tandem repeat gene clusters of chromosome 8 under heavy metal stress conditions. [ABSTRACT FROM AUTHOR]

The resurrection plant Ramonda serbica Panc. survives long desiccation periods and fully recovers metabolic functions within one day upon watering. This study aimed to identify key candidates and pathways involved in desiccation tolerance in R. serbica. We combined differential transcriptomics and proteomics, phenolic and sugar analysis, FTIR analysis of the cell wall polymers, and detailed analysis of the photosynthetic electron transport (PET) chain. The proteomic analysis allowed the relative quantification of 1192 different protein groups, of which 408 were differentially abundant between hydrated (HL) and desiccated leaves (DL). Almost all differentially abundant proteins related to photosynthetic processes were less abundant, while chlorophyll fluorescence measurements implied shifting from linear PET to cyclic electron transport (CET). The levels of H2O2 scavenging enzymes, ascorbate-glutathione cycle components, catalases, peroxiredoxins, Fe-, and Mn superoxide dismutase (SOD) were reduced in DL. However, six germin-like proteins (GLPs), four Cu/ZnSOD isoforms, three polyphenol oxidases, and 22 late embryogenesis abundant proteins (LEAPs; mainly LEA4 and dehydrins), were desiccation-inducible. Desiccation provoked cell wall remodeling related to GLP-derived H2O2/HO● activity and pectin demethylesterification. This comprehensive study contributes to understanding the role and regulation of the main metabolic pathways during desiccation aiming at crop drought tolerance improvement. [ABSTRACT FROM AUTHOR]

Background: Germin-like proteins (GLPs) are ubiquitous plant proteins, which play significant role in plant responses against various abiotic stresses. However, the potential functions of GLPs in rice (Oryza sativa) against salt and drought stress are still unclear. Methods and results: In this study, transcriptional variation of eight OsGLP genes (OsGLP3-6, OsGLP4-1, OsGLP8-4, OsGLP8-7, OsGLP8-10, OsGLP8-11 and OsGLP8-12) was analyzed in leaves and roots of two economically important Indica rice cultivars, KS282 and Super Basmati, under salt and drought stress at early seedling stage. The relative expression analysis from qRT-PCR indicated the highest increase in expression of OsGLP3-6 in leaves and roots of both rice varieties with a significantly higher expression in KS282. Moreover, relative change in expression of OsGLP8-7, OsGLP8-10 and OsGLP8-11 under salt stress and OsGLP8-7 under drought stress was also commonly higher in leaves and roots of KS282 as compared to Super Basmati. Whereas, OsGLP3-7 and OsGLP8-12 after salt stress and OsGLP8-4 and OsGLP8-12 after drought stress were observed with higher relative expression in roots of Super Basmati than KS282. Importantly, the OsGLP3-6 and OsGLP4-1 from chromosome 3 and 4 respectively showed higher expression in leaves whereas most of the OsGLP genes from chromosome 8 exhibited higher expression in roots. Conclusion: Overall, as a result of this comparative analysis, OsGLP genes showed both general and specific expression profiles depending upon a specific rice variety, stress condition as well as tissue type. These results will increase our understanding of role of OsGLP genes in rice crop and provide useful information for the further in-depth research on their regulatory mechanisms in response to these stress conditions. [ABSTRACT FROM AUTHOR]

Germins and germin-like proteins (GLPs) known as germination markers are encoded by multigene families in several plant species, including barley. To date, functional analysis has revealed germins and GLPs are involved in diverse processes such as embryonic development and stress responses. The aim of this study was the analysis of barley germins and GLPs. In this study, 80 putative germins and GLPs have been identified in barley by using known 17 germins and GLP sequences. Analysis of germins and GLPs showed all germins and GLPs are distributed on all seven chromosomes that most of them spread through chromosome 3, 4 and 7 with 16, 18 and 12 proteins on each, respectively. The protein sizes varied between 185 and 335 amino acids, with an average length of 225 aa. Twelve conserved motifs were found. While germin motifs 1 and 3 were detected in all germins and GLPs, some motifs were found to be related to signalization. Interestingly, protein–protein interaction analysis demonstrated some GLPs are associated with RAB6-interacting golgin, oligopeptide transmembrane transporter activity, beta-glucuronidase activity, protein N-linked glycosylation, multi-pass membrane protein, and proteins containing zinc finger (Znf) domain and RING (really interesting new gene)-type zinc finger domains. Our findings suggest that barley germins and GLPs may have diverse functions that make them important candidates for crop improvement. [ABSTRACT FROM AUTHOR]

Symbiotic strains of fungi in the genus Trichoderma affect growth and pathogen resistance of many plant species, but the interaction is not known in molecular detail. Here we describe the transcriptomic response of two cultivars of the crop Chenopodium quinoa to axenic co-cultivation with Trichoderma harzianum BOL-12 and Trichoderma afroharzianum T22. The response of C. quinoa roots to BOL-12 and T22 in the early phases of interaction was studied by RNA sequencing and RT-qPCR verification. Interaction with the two fungal strains induced partially overlapping gene expression responses. Comparing the two plant genotypes, a broad spectrum of putative quinoa defense genes were found activated in the cultivar Kurmi but not in the Real cultivar. In cultivar Kurmi, relatively small effects were observed for classical pathogen response pathways but instead a C. quinoa-specific clade of germin-like genes were activated. Germin-like genes were found to be more rapidly induced in cultivar Kurmi as compared to Real. The same germin-like genes were found to also be upregulated systemically in the leaves. No strong correlation was observed between any of the known hormone-mediated defense response pathways and any of the quinoa-Trichoderma interactions. The differences in responses are relevant for the capabilities of applying Trichoderma agents for crop protection of different cultivars of C. quinoa.

Germins and germin-like proteins (GLPs) were reported to participate in plant response to biotic and abiotic stresses involving hydrogen peroxide (H 2 O 2) production, but their role in mitigating heat stress is poorly understood. Here, we investigated the ability of a Solanum tuberosum L. GLP (StGLP) gene isolated from the yeast cDNA library generated from heat-stressed potato plants and characterized its role in generating innate and/or acquired thermo-tolerance to potato via genetic transformation. The transgenic plants exhibited enhanced tolerance to gradual heat stress (GHS) compared with sudden heat shock (SHS) in terms of maximal cell viability, minimal ion leakage and reduced chlorophyll breakdown. Further, three StGLP transgenic lines (G9, G12 and G15) exhibited enhanced production of H 2 O 2 , which was either reduced or blocked by inhibitors of H 2 O 2 under normal and heat stress conditions. This tolerance was mediated by up-regulation of antioxidant enzymes (catalase, ascorbate peroxidase and glutathione reductase) and other heat stress-responsive genes (StHSP70 , StHSP20 and StHSP90) in transgenic potato plants. These results demonstrate that H 2 O 2 produced by over-expression of StGLP in transgenic potato plants triggered the reactive oxygen species (ROS) scavenging signaling pathways controlling antioxidant and heat stress-responsive genes in these plants imparting tolerance to heat stress. • GLPs participating in plant response to biotic and abiotic stresses involving H 2 O 2 production. • Solanum tuberosum GLP gene isolated from the yeast cDNA library from heat-stressed plants. • Transgenic plants exhibited enhanced tolerance to gradual heat stress compared with sudden heat shock. • H 2 O 2 produced by over-expression of StGLP potato plants triggered the reactive oxygen species. [ABSTRACT FROM AUTHOR]

The resurrection plant Ramonda serbica Panc. survives long desiccation periods and fully recovers metabolic functions within one day upon watering. This study aimed to identify key candidates and pathways involved in desiccation tolerance in R. serbica. We combined differential transcriptomics and proteomics, phenolic and sugar analysis, FTIR analysis of the cell wall polymers, and detailed analysis of the photosynthetic electron transport (PET) chain. The proteomic analysis allowed the relative quantification of 1192 different protein groups, of which 408 were differentially abundant between hydrated (HL) and desiccated leaves (DL). Almost all differentially abundant proteins related to photosynthetic processes were less abundant, while chlorophyll fluorescence measurements implied shifting from linear PET to cyclic electron transport (CET). The levels of H2O2 scavenging enzymes, ascorbate-glutathione cycle components, catalases, peroxiredoxins, Fe-, and Mn superoxide dismutase (SOD) were reduced in DL. However, six germin-like proteins (GLPs), four Cu/ZnSOD isoforms, three polyphenol oxidases, and 22 late embryogenesis abundant proteins (LEAPs; mainly LEA4 and dehydrins), were desiccation-inducible. Desiccation provoked cell wall remodeling related to GLP-derived H2O2/HO● activity and pectin demethylesterification. This comprehensive study contributes to understanding the role and regulation of the main metabolic pathways during desiccation aiming at crop drought tolerance improvement.

Germin-like proteins (GLPs) are encoded by a family of genes found in all plants, and in terms of function, the GLPs are implicated in the response of plants to biotic and abiotic stresses. CchGLP is a gene encoding a GLP identified in a geminivirus-resistant Capsicum chinense Jacq accession named BG-3821, and it is important in geminivirus resistance when transferred to susceptible tobacco in transgenic experiments. To characterize the role of this GLP in geminivirus resistance in the original accession from which this gene was identified, this work aimed at demonstrating the possible role of CchGLP in resistance to geminiviruses in Capsicum chinense Jacq. BG-3821. Virus-induced gene silencing studies using a geminiviral vector based in PHYVV component A, displaying that silencing of CchGLP in accession BG-3821, increased susceptibility to geminivirus single and mixed infections. These results suggested that CchGLP is an important factor for geminivirus resistance in C. chinense BG-3821 accession.

Germins and germin-like proteins are ubiquitous, expressed at various developmental stages and in response to various abiotic and biotic stresses. In this study, to functionally validate the OsRGLP2 promoter, 5′ deletion analysis of the promoter sequences was performed and the deletion fragments fused with the β-glucuronidase (GUS) and green fluorescent protein reporter genes were used for transient expression in tobacco as well as for generating stable transgenic Arabidopsis plants. Very high level of GUS activity was observed in agroinfiltrated tobacco leaves by the construct carrying the P-1063 and P-565 when subjected to abiotic stresses. Histochemical analysis of transgenic Arabidopsis plants revealed expression of reporter gene in root, leaf and stem sections of plants harboring P-1063 and P-565. Real-time qPCR analysis of transiently expressed tobacco leaves and transgenic Arabidopsis plants subjected to several abiotic stresses supported histochemical data and showed that P-565 responded to all the stresses to which the full-length promoter was responsive. The data suggest that P-565 may be a good alternative to full-length promoter region that harbors the necessary cis-elements in providing stable and high level of expression in response to wound, salt and temperature stresses. [ABSTRACT FROM AUTHOR]

In transgenic plants, for many applications it is important that the inserted genes are expressed in a tissue-specific manner. This in turn could help better understanding their roles in plant development. Germin-like proteins (GLPs) play diverse roles in plant development and defense responses. In order to understand the functions and regulation of the GLP13 gene, its promoter (762 bp) was cloned and fused with a β-glucuronidase (GUS) reporter gene for transient expression in Arabidopsis thaliana and tobacco (Nicotiana tabacum cv. K326). Histochemical analysis of the transgenic plants showed that GUS was specifically expressed in vascular bundles predominantly in phloem tissue of all organs in Arabidopsis. Further analyses in transgenic tobacco also identified similar GUS expression in the vascular bundles.

To evaluate the effectiveness of a germin-like protein (GLP) in legumes against the serious soil-borne pathogen Fusarium oxysporum f. sp. lentis, an Oryza sativa root-expressed GLP ( OsRGLP1) was expressed in the model legume Medicago truncatula using the recombinant vector pC OsRGLP1. The transgene was highly expressed in M. truncatula transformed lines as assessed by RT-qPCR. Consistent with the active status of the transgene there was an elevated accumulation of HO in transformed progeny. Enzymatic characterization of T transgenic progeny showed increased superoxide dismutase (SOD) activity. The additional SOD activity in transgenic lines was insensitive to potassium cyanide and sensitive to HO indicating its resemblance to FeSOD. The effectiveness of the OsRGLP1 gene was tested by monitoring the root disease after infection of wild-type and transgenic lines. Wild-type plants were greatly affected by the pathogen infection showing a percent disease index value of 50 compared to 10-18 for the transgenic lines. The tolerance of the transgenic lines leads to recovery in fresh weight and pod production to an almost normal level. Analysis of defense-related genes downstream of hydrogen peroxide (HO) in transgenic plants showed induction of salicylic acid and jasmonate signaling pathways and increased expression of some pathogenesis-related-1 ( PR- 1) genes and a plant defensin gene. Overall, the findings suggest that OsRGLP1 provides protection against the fungal pathogen F. oxysporum that may involve the direct influence of HO on signaling pathways leading to the activation of defense-related genes. [ABSTRACT FROM AUTHOR]

Germin-like proteins (GLPs) are encoded by a family of genes found in all plants, and in terms of function, the GLPs are implicated in the response of plants to biotic and abiotic stresses. CchGLP is a gene encoding a GLP identified in a geminivirus-resistant Capsicum chineuse Jacq. accession named BG-3821, and it is important in geminivirus resistance when transferred to susceptible tobacco in transgenic experiments. To characterize the role of this GLP in geminivirus resistance in the original accession from which this gene was identified, this work aimed at demonstrating the possible role of CchGLP in resistance to geminiviruses in Capsicum chinense Jacq. BG-3821. Virus-induced gene silencing studies using a geminiviral vector based in PHYVV component A, displaying that silencing of CchGLP in accession BG-3821, increased susceptibility to geminivirus single and mixed infections. These results suggested that CchGLP is an important factor for geminivirus resistance in C. chineuse BG-3821 accession. [ABSTRACT FROM AUTHOR]

Copper (Cu) and cadmium (Cd) are common heavy metal pollutants. When Cd and excessive Cu accumulate in plants, plant growth is reduced. Our previous study showed that Germin-like proteins (GLPs), which exist in tandem on chromosomes, are a class of soluble glycoproteins that respond to Cu stress. In this study, hydroponic cultures were carried out to investigate the effect of GLP on Cd and Cu tolerance and accumulation in rice. The results showed that knockout of a single OsGLP8 - 2 gene or ten OsGLP genes ( OsGLP8 - 2 to OsGLP8 - 11 ) resulted in a similar sensitivity to Cd and Cu toxicity. When subjected to Cu and Cd stress, the glp8 - 2 and glp8 - (2 - 11) mutants displayed a more sensitive phenotype based on the plant height, root length, and dry biomass of the rice seedlings. Correspondingly, Cu and Cd concentrations in the glp8 - 2 and glp8 - (2 - 11) mutants were significantly higher than those in the wild-type (WT) and OsGLP8 - 2 -overexpressing line. However, Cu and Cd accumulation in the cell wall was the opposite. Furthermore, we determined lignin accumulation. The overexpressing- OsGLP8 - 2 line had a higher lignin accumulation in the shoot and root cell walls than those of the WT, glp8 - 2 , and glp8 - (2 - 11) . The expression of lignin synthesis genes in the OsGLP8 - 2 -overexpressing line was significantly higher than that in the WT, glp8 - 2 , and glp8 - (2 - 11) . The SOD activity of OsGLP8 - 2 , Diaminobe-nzidine (DAB), propidium iodide (PI) staining, and Malondialdehyde (MDA) content determination suggested that OsGLP8 - 2 is involved in heavy metal-induced antioxidant defense in rice. Our findings clearly suggest that OsGLPs participate in responses to heavy metal stress by lignin deposition and antioxidant defense capacity in rice, and OsGLP8-2 may play a major role in the tandem repeat gene clusters of chromosome 8 under heavy metal stress conditions., Competing Interests: Author AW was employed by the company CNTC. The remaining authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2023 ShangGuan, Qi, Wang, Ren, Wang, Xiao, Shen, Wang and Xia.)

In transgenic plants, for many applications it is important that the inserted genes are expressed in a tissue-specific manner. This in turn could help better understanding their roles in plant development. Germin-like proteins (GLPs) play diverse roles in plant development and defense responses. In order to understand the functions and regulation of the GLP13 gene, its promoter (762 bp) was cloned and fused with a β-glucuronidase ( GUS) reporter gene for transient expression in Arabidopsis thaliana and tobacco ( Nicotiana tabacum cv. K326). Histochemical analysis of the transgenic plants showed that GUS was specifically expressed in vascular bundles predominantly in phloem tissue of all organs in Arabidopsis. Further analyses in transgenic tobacco also identified similar GUS expression in the vascular bundles. [ABSTRACT FROM AUTHOR]

Emission and plant uptake of atmospheric nitrogen oxides (NO + NO) significantly influence regional climate change by regulating the oxidative chemistry of the lower atmosphere, species composition and the recycling of carbon and nutrients, etc. Plant uptake of nitrogen dioxide (NO) is concentration-dependent and species-specific, and covaries with environmental factors. An important factor determining NO influx into leaves is the replenishment of the substomatal cavity. The apoplastic chemistry of the substomatal cavity plays crucial roles in NO deposition rates and the tolerance to NO, involving the reactions between NO and apoplastic antioxidants, NO-responsive germin-like proteins, apoplastic acidification, and nitrite-dependent NO synthesis, etc. Moreover, leaf apoplast is a favorable site for the colonization by microbes, which disturbs nitrogen metabolism of host plants. For most plant species, NO assimilation in a leaf primarily depends on the nitrate (NO) assimilation pathway. NO–N assimilation is coupled with carbon and sulfur (sulfate and SO) assimilation as indicated by the mutual needs for metabolic intermediates (or metabolites) and the NO-caused changes of key metabolic enzymes such as phosphoenolpyruvate carboxylase (PEPc) and adenosine 5′-phosphosulfate sulfotransferase, organic acids, and photorespiration. Moreover, arbuscular mycorrhizal (AM) colonization improves the tolerance of host plants to NO by enhancing the efficiency of nutrient absorption and translocation and influencing foliar chemistry. Further progress is proposed to gain a better understanding of the coordination between NO–N, S and C assimilation, especially the investigation of metabolic checkpoints, and the effects of photorespiratory nitrogen cycle, diverse PEPc and the metabolites such as cysteine, O-acetylserine (OAS) and glutathione. [ABSTRACT FROM AUTHOR]

Rice oxalate oxidase genes (OXO) may play a role in resistance to Magnaporthe oryzae. Genome analyses showed four tandemly duplicated OXO genes, OsOXO1– OsOXO4, which mapped to a blast resistance QTL in chromosome 3. These genes have >90% nucleotide and amino acid identity, but they have unique gene structures, conserved motifs, and phylogeny compared to the 70 other members of the cupin superfamily in the Nipponbare genome, which were divided into several classes. In resistant and susceptible Vandana/Moroberekan advanced backcross lines, only OsOXO4 was expressed during rice– M. oryzae interactions, and its expression increased earlier in resistant than susceptible lines. The earlier expression of OsOXO4 in resistant lines correlated with a 26-bp promoter insertion containing an additional copy of the bacterial responsive nodulation cis-element. Our results showed that OsOXO1– 4 are in a separate class of rice cupin genes and supports a role for the promoter variant of OsOXO4 in resistance to M. oryzae. [ABSTRACT FROM AUTHOR]

A proteome approach based on 2-D gel electrophoresis (2-DE) was used to compare the protein patterns of the Arabidopsis ecotypes Col-0 and Ws-2. In leaf extracts a pair of protein spots were found to be diagnostic for each of the lines. Both pairs of spots were identified as closely related germin-like proteins differing in only one amino acid by using peptide mass finger printing of tryptic digests and by gaining additional data from post-source decay spectra in the MALDI-TOF analysis. Western blot analysis after separation of protein extracts by 2-DE confirmed results from Coomassie blue-stained gels and revealed additional immunoreactive spots for both ecotypes most likely representing dimers of the spots first identified. Western blot analysis and mass spectrometrical identification of the corresponding weakly stained protein in Coomassie blue-stained gels of the ecotype Col-0 also demonstrated for the first time the occurrence of AtGER3 protein in root extracts. Our results demonstrate the capacity of proteome analysis to analyse and distinguish closely related members of large protein families. [Copyright &y& Elsevier]

ABP19 and ABP20 (ABP19/20) have been isolated from the shoot apices of peach (Prunus persica L.) as proteins specifically bound to auxins. Sequence analysis has revealed that ABP19/20 are related to families of germin and germin-like proteins. Here, I showed that ABP19/20 were most abundant in young leaves and that their expression fluctuated during the light–dark cycle. These patterns of expression coincided with those of SaGLP and PnGLP, sequence homologues of ABP19/20. Both SaGLP and PnGLP have been isolated as transcripts that are specifically up-regulated in leaves during photoperiodic induction of flowering. In contrast, ABP19/20 expression in leaves was not correlated with the timing of flower bud initiation. In buds, ABP20 was expressed throughout development, whereas the expression of ABP19 mRNA was extremely low. ABP20 may have some role in the differentiation and development of both floral and vegetative buds. I also showed that the ABP19/20 protein has superoxide dismutase (SOD) activity. Several GLPs of different clades of the phylogenetic tree have SOD activity, suggesting that SOD may be widespread throughout proteins of the GLP family. Analysis of the 5′-flanking region of ABP19 revealed putative regulatory elements, including those that were auxin-responsive, light-regulated, and clock-responsive. [Copyright &y& Elsevier]

We have identified a limited number of proteins secreted into the nectar of tobacco plants. Nectarin I is the most highly expressed nectar protein and has a monomer molecular mass of 29 kDa. The other major nectar proteins are expressed at lower levels and have monomer molecular masses of 41, 54, and 65 kDa respectively. Nectarin I was purified and antiserum was raised against the protein. Under nondenaturing conditions, Nectarin I has an apparent molecular mass of >120 kDa. The expression of Nectarin I was restricted to nectary tissues and to a much lower level in the ovary. No Nectarin I was found in petals, stems, leaves, or roots or other floral tissues. The expression of Nectarin I was also developmentally regulated. It is expressed in nectary tissues only while nectar is being actively secreted. Subsequently, the N-terminus of purified Nectarin I was sequenced. Sequence identity showed Nectarin I is related to wheat germin. Although hydrogen peroxide is readily detectable in tobacco floral nectar, we were unable to demonstrate any oxalate oxidase activity for Nectarin I. A partial cDNA encoding the mature Nectarin I N-terminus was isolated and used to probe a Nicotiana plumbaginifolia genomic library. The Nectarin I gene was isolated and the translated sequence was consistent with both N-terminal and internal cyanogen bromide-derived amino acid sequence. The gene contains a single 386 nt intron and encodes a mature protein of 197 amino acids. [ABSTRACT FROM AUTHOR]

We have identified 39 Arabidopsis thaliana ESTs encoding germin-like proteins (GLPs) and have completely sequenced 25 of these cDNAs. Our analysis demonstrates that the Arabidopsis genome contains a gene family with at least 12 GLP genes. Comparisons with other known germins and germin-like proteins indicate that these Arabidopsis GLP subfamilies are unique from wheat germin. All other known GLPs fall into one of these subfamilies. The translated GLPs show approximately 35% amino acid identity with other GLPs outside of their subfamily and significantly higher levels of identity within their respective subfamily. The 3′ ends of many of the GLP cDNAs are heterogeneous and several sites of polyadenylation are used. Ten of the GLPs have N-terminal signal sequences and most appear to be exported from the cell. Structurally, the GLPs are predicted to have a high content of β-pleated sheet. Seven conserved regions of β-sheet were found in each of the GLP proteins along with α-helices located at both N- and C-termini. These same structural elements are also conserved in wheat germin. With one exception, all GLP family members contain at least one N-glycosylation site. All of these sites are conserved in an unstructured loop between β-1 and β-2. Genes for two of these GLPs were identified in genomic sequences previously deposited in the GenBank. The GLP3b gene is physically linked to the polyubiquitin 4 gene. The 3′ end of the GLP3b mRNA is only 0.5 kb from the ubq4 start of transcription. Analysis of the GLP3b promoter shows the presence of a single putative auxin-response sequence located at −124 to −111 upstream from the 5′ end of the GLP3b mRNA. The GLP9 gene was identified in an Arabidopsis contig from Chromosome 4.p> [ABSTRACT FROM AUTHOR]

Germin-like proteins (GLPs) ionically bound to the walls of preglobular somatic embryos of Pinus caribaea Morelet are markers of this early developmental stage. In order to reveal the physiological implications of such markers during early embryo development, we isolated a cDNA clone from somatic embryos predicted to encode a protein with sequence similarity to GLPs. PcGER1 has an open reading frame corresponding to a 220 amino acid polypeptide with a putative N-glycosylation site on Asn-69. The presence of a 24 amino acid putative signal peptide supports the hypothesis of an apoplastic location. The N-terminal 20 amino acid sequence of the predicted mature protein is identical to the amino terminal sequence of GP111, one of the extracellular pine GLPs previously identified. Southern blot hybridizations indicate that PcGER1 is probably unique in the pine genome. Transcripts homologous to PcGER1 are abundant in all embryogenic lines, absent from nonembryogenic lines, and present in quiescent zygotic embryos but not in the female gametophyte, the haploid storage tissue of conifers. Their abundance sharply decreases during germination. Isolation of gf-0.8, a genomic fragment identical to PcGER1 cDNA sequence, confirms that no introns disrupt the coding region as it has been already described for wheat gf-2.8 and gf-3.8 genomic clones. Recombinant PcGER1, produced in Escherichia coli, is recognized by antibodies raised against the GP111 N-terminal nonapeptide and the unglycosylated wheat germin monomer. The implications of GLPs in pine embryogenesis are discussed. [ABSTRACT FROM AUTHOR]

Symbiotic strains of fungi in the genus Trichoderma affect growth and pathogen resistance of many plant species, but the interaction is not known in molecular detail. Here we describe the transcriptomic response of two cultivars of the crop Chenopodium quinoa to axenic co-cultivation with Trichoderma harzianum BOL-12 and Trichoderma afroharzianum T22. The response of C. quinoa roots to BOL-12 and T22 in the early phases of interaction was studied by RNA sequencing and RT-qPCR verification. Interaction with the two fungal strains induced partially overlapping gene expression responses. Comparing the two plant genotypes, a broad spectrum of putative quinoa defense genes were found activated in the cultivar Kurmi but not in the Real cultivar. In cultivar Kurmi, relatively small effects were observed for classical pathogen response pathways but instead a C. quinoa -specific clade of germin-like genes were activated. Germin-like genes were found to be more rapidly induced in cultivar Kurmi as compared to Real. The same germin-like genes were found to also be upregulated systemically in the leaves. No strong correlation was observed between any of the known hormone-mediated defense response pathways and any of the quinoa- Trichoderma interactions. The differences in responses are relevant for the capabilities of applying Trichoderma agents for crop protection of different cultivars of C. quinoa ., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2021 Rollano-Peñaloza, Mollinedo, Widell and Rasmusson.)