Germin Gene Research Articles

Altered Activity of Peroxidase and Oxalate Oxidase Influences Lignification in Transgenic Tobacco

Peroxidase and hydrogen peroxide both play important roles in the final stages of the lignification pathway. Peroxidase, in the presence of H2O2 catalyses the oxidation of monolignols to give lignin. In order to examine this process we looked at lignification in transgenic tobacco plants expressing a barley peroxidase gene, HvPrx8, either alone or in combination with a wheat germin gene, g.f 2.8, which encodes oxalate oxidase, thereby providing a source of H2O2. Elevated activity of the antioxidant ascorbate peroxidase was found in plants expressing oxalate peroxidase and was greatly increased by co-expression with the barley peroxidase, although the latter had no effect when expressed alone. An increase was observed in the oxidation of the lignin monomer, syringaldazine in cell lines over-expressing barley peroxidase, while a decrease was observed in double transformants. Plants over-expressing barley peroxidase have elevated levels of lignin deposition compared to that of wild type tobacco plants. Over-expression of the individual enzymes was also shown to enhance heat-induced programmed cell death (PCD) in cell suspension cultures, an effect which was greatly reduced in the double-expressing lines.

Identification and analysis of the germin-like gene family in soybean

BackgroundGermin and germin-like proteins constitute a ubiquitous family of plant proteins. A role of some family members in defense against pathogen attack had been proposed based on gene regulation studies and transgenic approaches. Soybean (G. max L. Merr.) germin genes had not been characterized at the molecular and functional levels.ResultsIn the present study, twenty-one germin gene members in soybean cultivar 'Maple Arrow' (partial resistance to Sclerotinia stem rot of soybean) were identified by in silico identification and RACE method (GmGER 1 to GmGER 21). A genome-wide analyses of these germin-like protein genes using a bioinformatics approach showed that the genes located on chromosomes 8, 1, 15, 20, 16, 19, 7, 3 and 10, on which more disease-resistant genes were located on. Sequence comparison revealed that the genes encoded three germin-like domains. The phylogenetic relationships and functional diversity of the germin gene family of soybean were analyzed among diverse genera. The expression of the GmGER genes treated with exogenous IAA suggested that GmGER genes might be regulated by auxin. Transgenic tobacco that expressed the GmGER 9 gene exhibited high tolerance to the salt stress. In addition, the GmGER mRNA increased transiently at darkness and peaked at a time that corresponded approximately to the critical night length. The mRNA did not accumulate significantly under the constant light condition, and did not change greatly under the SD and LD treatments.ConclusionsThis study provides a complex overview of the GmGER genes in soybean. Phylogenetic analysis suggested that the germin and germin-like genes of the plant species that had been founded might be evolved by independent gene duplication events. The experiment indicated that germin genes exhibited diverse expression patterns during soybean development. The different time courses of the mRNAs accumulation of GmGER genes in soybean leaves appeared to have a regular photoperiodic reaction in darkness. Also the GmGER genes were proved to response to abiotic stress (such as auxin and salt), suggesting that these paralogous genes were likely involved in complex biological processes in soybean.

Salt stress causes a shift in the localization pattern of germin gene expression

The response of plants to biotic and abiotic stress factors involves biochemical, physiological, morphological, and developmental changes. Salt stress has been the subject of extensive studies due to the low salt tolerance of many crop plants. Germin and germin-like gene products are known to be involved in various aspects of plant development, such as defense, embryonic development and response to biotic as well as abiotic stress, including salt. The responses of germin and germin-like genes to salt stress vary in different plants. RT-PCR and in situ RNA hybridization methods were employed to analyze quantitative changes and to detect the localization pattern of germin gene products in salt-stressed and water-grown wheat embryos. Salt stress caused no quantitative changes in the synthesis of germin gene products. However, in situ RNA hybridization revealed changes in the expression site of germin gene products. Coleorhiza cells were found to be the site of germin accumulation in water-grown embryos; however, in salt-stressed embryos, germin mRNA accumulated in coleoptile cells instead of coleorhiza tissue.

Inter-simple sequence repeat (ISSR) loci mapping in the genome of perennial ryegrass

The aim of this study was to identify and characterize new ISSR markers and their loci in the genome of perennial ryegrass. A subsample of the VrnA F2 mapping family of perennial ryegrass comprising 92 individuals was used to develop a linkage map including inter-simple sequence repeat markers (ISSR). Twelve ISSR fragments out of 29 were mapped to the linkage groups (LG) LG1, LG2, LG4, LG6 and LG7. The total map length was 250.7 cM. Selected ISSR fragments were cloned by transformation into plasmid pTZ57R and sequenced. For four ISSRs, BLAST search revealed a significant similarity to coding regions of known sequences within the current DNA databases. An ISSR fragment of 580 bp, produced by the (GACA)4TC primer present on LG6, showed a 95% identity to the Avena sativa L. transposon and repetitive DNA linked to the receptor kinase gene. A 780 bp fragment generated by (TG)8RT primer demonstrated a 70% similarity to the Hordeum vulgare germin gene GerA. Inter-SSR mapping will provide useful information for gene targeting, quantitative trait loci mapping and marker-assisted selection in perennial ryegrass.

The PDI genes of wheat and their syntenic relationship to the esp2 locus of rice

The storage protein polymers in the endosperm, stabilised by disulphide bonds, determine a number of processing qualities of wheat dough. The enzyme protein disulphide isomerase (PDI), involved in the formation of disulphide bonds, is strongly suggested to play a role in the formation of wheat storage protein bodies. Reports of the rice mutant esp2 exhibiting aberrant storage protein deposition in conjunction with a lack of PDI expression provided strong indications of a direct role for PDI in storage protein deposition. The potential significance of wheat PDI prompted the present studies into exploring any orthology between wheat PDI genes and rice PDI and esp2 loci. By designing allele-specific (AS)-polymerase chain reaction (PCR) markers, two of the three wheat PDI genes could be genetically mapped to group 4 chromosomes and showed close association with GERMIN genes. Physical mapping led to localisation of wheat PDI genes to chromosomal "bins" on the proximal section of chromosome 4AL and distal sections of 4BS and 4DS. Identification of the putative PDI gene of rice and its comparison to the esp2 locus revealed that they were present at similar positions on the short arm of chromosome 11. Analysis of a large section of the PDI-containing section of rice chromosome 11S revealed a number of putative orthologues from The Institute for Genomic Research Triticum aestivum Gene Index database, of which five had been mapped, each localising to group 4 chromosomes, many in good agreement with our mapping results. The results strongly suggest a close linkage between the esp2 marker and the PDI gene of rice and an orthology between the PDI loci of rice and wheat and predict quantitative-trait loci involved in storage protein deposition at the PDI loci.

Localization of germin genes and their products in developing wheat coleoptiles.

Germination is a process which characterized with nescient synthesis of genes. Among the genes synthesized during the germination of wheat embryos, germin genes, proteins and their enzymatic activity were defined. Germin is a water soluble homopentameric glycoprotein which is remarkable resistant to degradation by a broad range of proteases including pepsin. Germin proteins found to have strong oxalate oxidase activity which produces hydrogen peroxide by degrading oxalic acid. The current study, aimed to localize the germin genes, proteins and enzymatic activities in developing coleoptiles which is a rapidly growing protective tissue of leaf primordium and shoot apex. Non-radioactively labeled germin riboprobes were employed to localize germin mRNAs in situ. FITC (Fluorescein isothiocyanate) and alkaline phosphatase linked anti-germin antibodies were used to localize germin proteins under the fluorescence and light microscopy and finally germin enzymatic activity was localized by using appropriate enzyme assay. The results revealed that in coleoptiles germin genes, proteins and their enzymatic activity were predominantly associated with the cells of epidermis and vascular bundle sheath cells.

Spatial Localization of Germin-Like Oxalate Oxidase Genes in Developing Wheat Shoots

ABSTRACTWhen quiescent embryos in dry grains of ripened wheat are isolated and provided with ample water and oxygen at an appropriate temperature, they begin to grow very rapidly. The onset of the growth is signaled by nascent synthesis of germin genes which encodes a relatively rare, water-soluble homop entameric glycoprotein. Germin is resistant to pepsin digestion under conditions that lead to hydrolysis of virtually all other proteins in wheat embryos. Germin proteins have oxalate oxidase activity, an activity that degrades oxalic acid to generate hydrogen peroxide which involves in many aspects of plant development.Following 48-hour imbibition on water, wheat embryos give rise to distinguishable shoot and roots. Shoots comprise coleoptile, leaf primordium and shoot apex. In the current study, non-radioactively labeled germin riboprobes were prepared by in vitro transcription. The riboprobes were used to search and localize germin mRNAs in sections taken from throughout of shoots. The results revealed that although leaf primordium and shoot apex did not show any signals of the presence of germin mRNAs, coleoptiles as a whole tissue displayed germin gene expression on epidermal cells and vascular bundle sheath cells. Among the sections taken from different parts of shoots, the sections from middle part gave the strongest signals on coleoptile cells.

Oxalate oxidase: a novel reporter gene for monocot and dicot transformations

A wheat germin gene, with oxalate oxidase (OxO) activity, can be used as a sensitive reporter gene in both monocot and dicot transformations. Detection of H2O2 generated from OxO oxidation of oxalate provides simple, rapid detection of gene expression. Inexpensive substrates are required for both assays. OxO activity, could be detected histochemically in minutes, without chlorophyll clearing procedures. This assay was used to optimize transformation procedures and to track stable transgene expression in breeding populations over many generations. A simple spectrophotometric quantitative enzyme activity assay was used to select lines with various levels of transgene expression and to monitor transgene silencing phenomena. The quantitative OxO assay can also be used as an internal DNA delivery standard with a second reporter gene used in gene expression studies. The simplicity of the assay is ideal for screening large populations to identify primary transgenics, for monitoring transgene segregation in large populations in field studies and for assessing stability of transgene expression over numerous generations.

Partial Resistance to White Mold in a Transgenic Soybean Line

Oxalic acid is an important pathogenic factor for the fungus Sclerotinia sclerotiorum (Lib.) de Bary. An oxalate degrading enzyme, oxalate oxidase (OxO), in transgenic soybean [Glycine max (L.) Merr.] has reduced pathogen growth in indoor seedling studies. The objective of this study was to characterize the response of this OxO transgenic soybean line to white mold under field conditions and also to characterize the agronomic performance of this transgenic line under noninfected conditions. The transgenic line 80(30)-1contains the wheat germin gene gf-2.8 that codes for OxO. This line was compared with 80(30)-9, a sib line which does not contain the gene, as well as resistant and susceptible cultivars. Field tests were conducted at three sites infested with white mold in Ontario and Quebec across 3 yr. The Sainte-Foy site provided the highest infection potential and the transgenic line had a disease severity index (DSI) of 7 compared with 80(30)-9 with a DSI of 46, across 3 yr. Across 2 yr, resistant commercial cultivars had an average DSI of 2 and susceptible cultivars a DSI of 46. Stem inoculations were performed in the field at Elora and the transgenic line was significantly less infected compared with 80(30)-9. In noninfested trials, no significant differences were found between the transgenic, the negative sib, and the parental lines for seed yield, maturity, seed weight, or seed protein and oil content. The transgene provided white mold resistance equivalent to the best commercial cultivars in a white mold susceptible background.

A Novel Application for Determination of Germin Gene Products In Situ

ABSTRACTIn situ nucleic acid hybridization is one of the most powerful techniques developed for localizing the expression site of a particular gene at the cell, tissue and organ levels. This method is especially useful in understanding the function of specific gene products in particular tissues and the relation between tissue function and its localization in the whole structure of an organ. In this system, labeled anti-sense RNA probes were used to hybridize with desired mRNA while labeled sense probes were used as negative control. In general, each of these labeled probes applied to successive sections rather then the same section. That might cause some uncertainty if there are any spatial differences in the expression of gene products. In the current study, in our knowledge for the first time, anti-sense and sense probes were applied to the same sample to overcome any spatial differentiation of gene expression. The technique was successfully used to localize a plant gene product by applying anti-sense probes to the one site of the section while the other site of the same section was reacted with sense probes for control hybridization.

Partial Resistance to White Mold in a Transgenic Soybean Line

Oxalic acid is an important pathogenic factor for the fungus Sclerotinia sclerotiorum (Lib.) de Bary. An oxalate degrading enzyme, oxalate oxidase (OxO), in transgenic soybean [Glycine max (L.) Merr.] has reduced pathogen growth in indoor seedling studies. The objective of this study was to characterize the response of this OxO transgenic soybean line to white mold under field conditions and also to characterize the agronomic performance of this transgenic line under noninfected conditions. The transgenic line 80(30)‐1contains the wheat germin gene gf‐2.8 that codes for OxO. This line was compared with 80(30)‐9, a sib line which does not contain the gene, as well as resistant and susceptible cultivars. Field tests were conducted at three sites infested with white mold in Ontario and Quebec across 3 yr. The Sainte‐Foy site provided the highest infection potential and the transgenic line had a disease severity index (DSI) of 7 compared with 80(30)‐9 with a DSI of 46, across 3 yr. Across 2 yr, resistant commercial cultivars had an average DSI of 2 and susceptible cultivars a DSI of 46. Stem inoculations were performed in the field at Elora and the transgenic line was significantly less infected compared with 80(30)‐9. In noninfested trials, no significant differences were found between the transgenic, the negative sib, and the parental lines for seed yield, maturity, seed weight, or seed protein and oil content. The transgene provided white mold resistance equivalent to the best commercial cultivars in a white mold susceptible background.

Soybean plants expressing an active oligomeric oxalate oxidase from the wheat gf-2.8 (germin) gene are resistant to the oxalate-secreting pathogen Sclerotina sclerotiorum

Sclerotinia stem rot (SSR) caused by Sclerotinia sclerotiorum (Lib.) De Bary is a serious fungal disease of soybean. Senescing petals provide a starting nutrient source for the invasion of healthy tissue by the advancing oxalic acid secreting fungal hyphae. Since oxalic acid is a major pathogenicity factor of SSR, transgenic soybean capable of degrading oxalic acid may be resistant to the pathogen. Transgenic soybean plants were produced byAgrobacterium -mediated transformation with the wheat germin gene (gf-2.8) encoding an oligomeric protein, oxalate oxidase (OxO), which oxidizes oxalic acid to carbon dioxide and hydrogen peroxide (H2O2). Transgenic soybean homozygous for 35S- gf-2.8 produced an approx. 130kDa protein indistinguishable from wheat germin, and with OxO activity. OxO activity was prominent in cell walls proximal to the site of pathogen attack. The transgenics had greatly reduced disease progression and lesion length following cotyledon and stem inoculation with S. sclerotiorum indicating that the germin gene product conferred resistance to SSR. This is the first report of plant resistance to the fungal pathogen S. sclerotiorum in transgenic plants expressing OxO.

Functional characterization of seed coat-specific members of the barley germin gene family

The present project aimed to isolate testa-, pericarp- and epicarp-specific gene promoters for the developing caryopsis of barley ( Hordeum vulgare L.). These might be applied in transgenic plants to express antifungal agents or modify metabolic pathways. A testa-specific 379-nucleotide fragment was cloned by differential amplification and used to screen a bacterial artificial chromosome (BAC) library of 6.3 haploid genome equivalents. Fifty-three clones containing genes encoding for proteins of the germin family were found. Characterization of the clones identified a minimum of six seed coat- and eight leaf-specific germin genes. Four seed coat- and one leaf-specific genes were sequenced. The deduced primary structure of the proteins revealed a remarkable conservation of the manganese(II) binding His and Glu residues and β-barrel secondary structure of oxalate oxidase – also in barley, wheat, rice and Arabidopsis germins, for which an enzymatic activity has not yet been identified. The oxalate oxidase and germins of barley and other species are synthesized with a conserved pre-sequence of 23 or 24 amino acids for targeting into the cell wall. β-Glucuronidase expression with the barley germin F gene promoter occurs specifically in the testa and epicarp of the developing barley caryopsis, while expression with the B gene promoter is restricted to the testa. Oxalate oxidase activity is prominent in the epicarp and the root tips of the developing embryo. A family tree based on primary structure homologies of germins distinguishes three groups: oxalate oxidases, leaf-specific germins and seed coat-specific germins.

Regulation by biotic and abiotic stress of a wheat germin gene encoding oxalate oxidase, a H2O2-producing enzyme.

Germins and germin-like proteins (GLPs) constitute a ubiquitous family of plant proteins that seem to be involved in many developmental and stress-related processes. Wheat germin has been extensively studied at the biochemical level: it is found in the apoplast and the cytoplasm of germinating embryo cells and it has oxalate oxidase activity (EC 1.2.3.4). Germin synthesis can also be induced in adult wheat leaves by auxins and by a fungal pathogen but it remains to be determined whether the same gene is involved in developmental, hormonal and stress response. In this work, we have studied the expression of one of the wheat germin genes, named gf-2.8, in wheat as well as in transgenic tobacco plants transformed with either this intact gene or constructs with GUS driven by its promoter. This has allowed us to demonstrate that expression of this single gene is both developmentally and pathogen-regulated. In addition, we show that expression of the wheat gf-2.8 germin gene is also stimulated by some abiotic stresses, especially the heavy metal ions Cd2+, Cu2+ and Co2+. Several chemicals involved in stress signal transduction pathways were also tested: only polyamines were shown to stimulate expression of this gene. Because regulation of the wheat gf-2.8 germin gene is complex and because its product results in developmental and stress-related release of hydrogen peroxide in the apoplast, it is likely that it plays an important role in several aspects of plant growth and defence mechanisms.

Gene expression and oxalate oxidase activity of two germin isoforms induced by stress

Wheat germin is a homopentameric 125 kD glycoprotein mainly localized in the cell wall of monocots, and is a specific marker of the onset of growth in germinating seeds. The major objective of this study was to examine the expression and oxalate oxidase activity of two wheat germin isoforms: gf-2.8 and gf-3.8 in transgenic tobacco plants. The transgenic tobacco plants were created with different constructs: 1) one entire excision of gf-2.8 germin promoter and two partially deleted promoter sequences were used to generate 3 independent GUS constructs; 2) the whole gf-2.8 gene construct and the fusion with CaMV 35S promoter; 3) one entire excision of gf-3.8 germin gene and one partially deleted gf-3.8 promoter sequences were used to generate 2 independent GUS constructs; 4) the whole gf-3.8 gene and the fusion with CaMV 35S promoter. Hormonal treatment (auxin and gibberellin), salt treatment, heavy metals (Mn, Fe, Co, Ni, Cu, Zn, Cd, Hg, As) and Al induced high GUS activity in tobacco transformed with entire and one partially deleted of the gf-2.8 gene. The immunoblotting confirmed induction of gf-2.8 gene and its product expressed oxalate oxidase activity in tobacco transformed with the entire gf-2.8 construct. Neither nicotinic acid, salicylic acid, heat shock, cold nor UV-C have enhanced significant GUS activity and germin gf-2.8 synhesis and activity.

Presence and organization of an osmotic stress response domain in wild Triticeae species

Sixteen Triticeae species of the genera Aegilops L., Pseudoroegneria (Nevski) Love, Taeniatherum Nevski and Thinopyrum Love were investigated by PCR amplification for the presence of a wheat germin gene internal domain involved in osmotic stress resistance. In all of the species studied a single band of identical or very similar size was detected, After cloning and sequencing of these fragments, different degrees of homology were found with the original wheat domain, which suggested that in these species there are functional differences in the osmotic response involving the germin core.

Regulated expression of a wheat germin gene in tobacco: oxalate oxidase activity and apoplastic localization of the heterologous protein.

Wheat (Triticum aestivum) germin is a homopentameric glycoprotein whose synthesis is allied with seed germination. Germin pentamers show an unusual resistance to dissociation and possess an oxalate oxidase (OxO) activity. In order to increase our knowledge of germin gene expression, the function(s) of germin during development and possible uses in plant genetic engineering, an in vivo expression system is required. To this end, a gene for germin, named gf-2.8, was studied by expressing either promoter-GUS fusions or the intact gene in transgenic tobacco (Nicotiana tabacum) plants. Heterologous gene transcription was monitored in vitro and in vivo by GUS or OxO activity and was found to occur in developing seeds and in seedlings. This transcription was stimulated by auxins, as would be expected because of the presence of putative auxin-responsive elements in the promoter of the gf-2.8 gene. Auxin stimulation also extended to young leaves since OxO activity could be detected in treated but not in untreated leaves. The biochemical characteristics of wheat germin were also conserved in a transgenic host: the OxO activity was present under the form of a doublet co-migrating with germin G and G' isoforms. Also, germin distributed between a soluble and an apoplastic fractions despite the fact that wheat cell wall substantially differs from tobacco cell wall. Therefore, tobacco constitutes a suitable host for in vivo studies of this monocotyledon gene.

Germin Gene Expression Is Induced in Wheat Leaves by Powdery Mildew Infection.

Germin gene expression is induced in wheat (Triticum aestivum L.) leaves by powdery mildew (Erysiphe graminis f. sp. tritici) infection. Germin is a protein marker for early cereal development and is an oxalate oxidase, an enzyme that catalyzes the conversion of oxalate to CO2 and H2O2. The induction of germin gene expression by powdery mildew infection is consistent with the importance of H2O2 to plant defense and identifies a mechanism for the elevation of H2O2 levels in wheat leaves. Germin mRNA levels increased 2 d after inoculation of seedlings with powdery mildew and continued to increase throughout an 8-d time course. The increase in accumulation of germin mRNA was accompanied by an increase in the germin oligomer, which reached maximal levels by d 6. An increase in oxalate oxidase activity paralleled germin oligomer accumulation. Germin gene expression was induced in a relatively resistant cultivar (Bobwhite) as well as in a susceptible cultivar (Cheyenne), suggesting that the induction of germin gene expression is an indicator of powdery mildew infection rather than cultivar resistance.

Effect of Salt Stress on Germin Gene Expression in Barley Roots.

Germin gene expression in barley (Hordeum vulgare L.) seedlings responds to developmental and environmental cues. During seed germination, germin mRNA levels were maximal 2 d after the start of imbibition in control seedlings and declined to low levels by 6 d. When seeds were sown in the presence of 200 mM NaCl, germin mRNA levels were also maximal after 2 d, but NaCl treatment, which slowed seedling growth, prolonged germin gene expression for an additional 1 d. In 4-d-old seedlings, germin mRNA levels were highest in roots and higher in the vascular transition region than in shoots. In roots of 6-d-old seedlings, germin gene expression was regulated by salt shock and plant growth regulators. Induced germin mRNA levels were maximal 8 h after treatment with NaCl, salicylate, methyl salicylate, or methyl jasmonate and 4 h after treatment with abscisic acid and indoleacetic acid. Like germin mRNA, dehydrin mRNA levels were maximal 8 h after NaCl treatment. In contrast, peroxidase mRNA levels declined to less than control levels within 30 min of treatment. Germin gene expression is regulated developmentally by salt stress and by treatments with plant hormones. Since germin is an oxalate oxidase, these result imply that oxalate has important roles in plant development and homeostasis.

Homologies between members of the germin gene family in hexaploid wheat and similarities between these wheat germins and certain Physarum spherulins

By screening approximately 10(6) plaques in a wheat DNA library with a "full-length" germin cDNA probe, two genomic clones were detected. When digested with EcoRI, one clone yielded a 2.8-kilobase pair fragment (gf-2.8) and the other yielded a 3.8-kilobase pair fragment (gf-3.8). By nucleotide sequencing, each of gf-2.8 and gf-3.8 was found to encode a complete sequence for germin and germin mRNA, and to contain appreciable amounts of 5'- and 3'-flanking sequences. The "cap" site in gf-2.8 was determined by primer extension and the corresponding site in gf-3.8 was deduced by analogy. The mRNA coding sequences in gf-2.8 and gf-3.8 are intronless and 87% homologous with one another. The 5'-flanking regions in gf-2.8 and gf-3.8 contain recognizable sites of what are probably cis-acting elements but there is otherwise little if any significant similarity between them. In addition to putative TATA and CAAT boxes in the 5'-flanking regions of gf-2.8 and gf-3.8, there are AT-rich inverted-repeats, GC boxes, long purine-rich sequences, two 19-base pair direct-repeat sequences in gf-2.8, and a remarkably long (200-base pair) inverted-repeat sequence (approximately 90% homology) in gf-3.8. An 8% difference between the mature-protein coding regions in gf-2.8 and gf-3.8 is reflected by a corresponding 7% difference between the corresponding 201-residue proteins. Most significantly, the same 8% difference between the mature-protein coding regions in gf-2.8 and gf-3.8 is allied with no change whatever in a central part (61-151) of the encoded polypeptide sequences. It seems likely that this central, strongly conserved core in the germins is of first importance in the biochemical involvements of the proteins. When an equivalence is assumed between like amino acids, the gf-2.8 and gf-3.8 germins show significant (approximately 44%) similarity to spherulins 1a and 1b of Physarum polycephalum, a similarity that increases to approximately 50% in the conserved core of germin. Near the middle (87-96) of the conserved core in the germins is a rare PH(I/T)HPRATEI decapeptide sequence which is shared by spherulins (1a and 1b) and germins (gf-2.8 and gf-3.8). These similarities are discussed in the context of evidence which can be interpreted to suggest that the biochemistry of germins and spherulins is involved with cellular, perhaps cell-wall responses to desiccation, hydration, and osmotic stress.(ABSTRACT TRUNCATED AT 400 WORDS)