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Douglas-fir (DF) (Pseudotsuga menziesii) is one of the largest and most economically important coniferous species in western North America. Its productivity is greatly affected by the root rot fungus Phellinus sulphurascens Pilát. Evidence of resistance by DF to fungal root pathogens such as P. sulphurascens has been reported but mechanisms of resistance in this compatible pathosystem are not yet known. To better understand the DF–P. sulphurascens interaction, especially at the molecular level, we selected 12 diverse plant genes already identified as defense-related from a cDNA library constructed using root tissues from P. sulphurascens-infected DF seedlings. Using quantitative reverse-transcriptase polymerase chain reaction on infected DF root samples collected at five different time points after inoculation, we found that P. sulphurascens infection significantly elevated expression of the 12 selected genes. In most cases the highest expression level was recorded within 2 to 3 days after inoculation. The constructed cDNA library, which is enriched with defense-related host genes and a number of fungal genes, will continue to serve as a useful resource for future larger-scale gene discovery and functional research on the P. sulphurascens and DF pathosystem.

The PmPR10-1.10 protein from western white pine is known to be associated with frost hardiness, and up-regulated by seasonal cold acclimation and biotic and abiotic stresses. To gain insight into the molecular basis of cold hardiness, we investigated the potential physiological role of PmPR10-1.10 by gene overexpression in transgenic Arabidopsis plants. A binary vector was constructed for PmPR10-1.10 synthesis in higher plants and transgenic Arabidopsis lines were generated by Agrobacterium-mediated transformation. Following Western protein blot analysis confirming target protein production, transgenic Arabidopsis lines were tested for cold tolerance by electrolyte leakage analysis post treatment of different freezing temperatures. Our results demonstrate that accumulation of PmPR10-1.10 protein resulted in significantly greater freezing tolerance in transgenic plants than in wild type plants. This indicates that the transfer and selection of cold acclimation proteins like PmPR10-1.10 may be a breeding strategy for the development of freezing tolerance in conifers.

Canola (Brassica napus), an agriculturally important oilseed crop, can be significantly affected by diseases such as sclerotinia stem rot, blackleg, and alternaria black spot resulting in significant loss of crop productivity and quality. Cysteine-rich antimicrobial peptides isolated from plants have emerged as a potential resource for protection of plants against phytopathogens. Here we report the significance of an antimicrobial peptide, PmAMP1, isolated from western white pine (Pinus monticola), in providing canola with resistance against multiple phytopathogenic fungi. The cDNA encoding PmAMP1 was successfully incorporated into the genome of B. napus, and it's in planta expression conferred greater protection against Alternaria brassicae, Leptosphaeria maculans and Sclerotinia sclerotiorum. In vitro experiments with proteins extracted from transgenic canola expressing Pm-AMP1 demonstrated its inhibitory activity by reducing growth of fungal hyphae. In addition, the in vitro synthesized peptide also inhibited the growth of the fungi. These results demonstrate that generating transgenic crops expressing PmAMP1 may be an effective and versatile method to protect susceptible crops against multiple phytopathogens.

Summary To better understand the molecular basis of interactions between the laminated root rot pathogen Phellinus sulphurascens Pilat and its principal host, Douglas-fir [DF; Pseudotsuga menziesii (Mirb.) Franco.], we constructed a cDNA library from roots of P. sulphurascens-infected DF seedlings. From a total of 3600 random cDNA clones, we identified 56 clones that matched with barley wound induced (barwin)-type pathogenesis-related 4 (PR4) genes that have been reported in planta. At least three PR4 genes comprising 426- to 444-bp full-length open reading frames, Pm PR4a1, Pm PR4a2, and Pm PR4b1, were identified from DF seedlings. Deduced amino acid sequences for the proteins encoded by these genes confirmed that two of them are acidic (Mr, 12.8–13.0 kDa; pI, 4.12–4.53) and one is a basic (Mr, 13.0 kDa; pI, 8.53) PR4 protein. Quantitative reverse transcriptase-PCR analyses of these transcripts showed significantly higher transcription in P. sulphurascens-infected vs. control DF tissues. Upregulation of the transcripts in roots of a P. sulphurascens-resistant DF family was significant. Our results suggest that DF PR4 genes play an important role in the defence mechanism of DF against P. sulphurascens infection and thus could be useful in DF breeding.

Multiple families of pathogenesis-related (PR) proteins are believed to contribute to plant quantitative resistance to various pathogens. Along with other host PR proteins, PR3 chitinase is one protein component participating in genetic resistance of western white pine (Pinus monticola) to the white pine blister rust (WPBR) pathogen (Cronartium ribicola). In the present study, we characterized a novel P. monticola class IV chitinase gene (PmCh4B) and further analyzed its nucleotide variations in the open-pollinated seed families of diverse geographical distribution and variable levels of quantitative resistance to C. ribicola infection. PmCh4B showed high haplotype diversity (Hd = 0.94) and nucleotide diversity (π = 0.00965), similar to those of other conifer genes related to environmental stresses. A low level of intragenic linkage disequilibrium (LD) (but most of the levels with statistical significance) was found within a distance of ≈800 bp. Based on PmCh4B haplotype frequency, moderate to high levels of population structure were observed among P. monticola seed families currently used in breeding programs for WPBR resistance (average FST = 0.163, P < 0.001). Association analysis revealed that allelic variants and multiple single-nucleotide polymorphisms of PmCh4B were significantly associated with quantitative levels of P. monticola resistance against C. ribicola. This work represents the first association study for quantitative resistance in western white pine pathosystem and provides a potential for marker-assisted selection in white pine breeding.

Cronartium ribicola causes white pine blister rust (WPBR) in subgenus Strobus. Various genetic and molecular approaches were used to detect white pine genes contributing to host resistance. The molecular role of the NBS-LRR family is highly related to plant immuno-activity against various pathogens and pests. In the present study, genomic organization of a resistance gene analog (RGA), designated as PmTNL1, and its allelic variants were characterized in Pinus monticola. PmTNL1 showed high identity with TIR-NBS-LRR proteins from other plants. qRT-PCR revealed that the PmTNL1 transcript was expressed at low basal levels in different tissues and exhibited similar patterns during compatible and incompatible interactions of P. monticola with C. ribicola at early stages post inoculation. In comparison, PmTNL1 was up-regulated significantly in diseased P. monticola tissues with WPBR symptoms. Expression of the PmTNL1 promoter::GUS fusion gene in transgenic Arabidopsis demonstrated that GUS signal appeared only inside phloem tissues of young seedlings and at hydathodes and branching and organ-connecting points in mature Arabidopsis plants. Similar to the endogenous expression pattern for this gene in pine, GUS activity was up-regulated significantly around vascular tissues locally at pathogen infection sites, but little or no induction was observed in response to abiotic stresses. A DNA marker was developed based on variation of the LRR-coding region, and PmTNL1 was mapped to one genetic linkage group using a pedigree with major dominant gene (Cr2) conferring HR resistance to C. ribicola. These results suggest that PmTNL1 may play an important role in white pine partial resistance against C. ribicola.

Laminated root rot (LRR) disease, caused by the fungus Phellinus sulphurascens, is a major threat to coastal Douglas-fir (DF) (Pseudotsuga menziesii) forests in western North America. Understanding host–pathogen interactions of this pathosystem is essential to manage this important conifer root disease. Our research objectives were to identify DF pathogenesis-related (PR) genes and analyze their expression patterns over the course of infection. We constructed a cDNA library of Phellinus sulphurascens-infected DF seedling roots and sequenced a total of 3,600 random cDNA clones from this library. One of the largest groups of identified genes (203 cDNA clones) matched with chitinase genes reported in other plant species. We identified at least three class II and six class IV chitinase genes from DF seedlings. Quantitative reverse-transcriptase polymerase chain reaction analyses showed significant differential expression patterns locally in root tissues and systemically in needle tissues after fungal invasion. Nonetheless, there was a common trend in gene expression patterns for most of the chitinase genes: an upregulation within 12 h of pathogen inoculation followed by down-regulation within 2 to 3 days postinoculation (dpi), and then further upregulation within 5 to 7 dpi. Western immunoblot data showed differential accumulation of class IV chitinases in Phellinus sulphurascens-infected DF seedlings. Further detailed functional analyses will help us to understand the specific role of DF chitinases in defense against Phellinus sulphurascens infection.

Thaumatin-like proteins (TLPs) are the products of a large, highly complex gene family involved in host defence and a wide range of developmental processes in fungi, plants, and animals. Despite their dramatic diversification in organisms, TLPs appear to have originated in early eukaryotes and share a well-defined TLP domain. Nonetheless, determination of the roles of individual members of the TLP superfamily remains largely undone. This review summarizes recent advances made in elucidating the varied TLP activities related to host resistance to pathogens and other physiological processes. Also discussed is the current state of knowledge on the origins and types of TLPs, regulation of gene expression, and potential biotechnological applications for TLPs.

Phloem exudate collected from hybrid poplar (Populus trichocarpa x Populus deltoides) was estimated to have more than 100 proteins, of which 48 were identified using LC-MS/MS. Comparative two-dimensional gel electrophoresis demonstrated that two phloem exudate proteins were significantly (P

The WRKY gene family represents an ancient and highly complex group of transcription factors involved in signal transduction pathways of numerous plant developmental processes and host defense response. Up to now, most WRKY proteins have been identified in a few angiosperm species. Identification of WRKY genes in a conifer species would facilitate a comprehensive understanding of the evolutionary and function-adaptive process of this superfamily in plants. We performed PCR on genomic DNA to clone WRKY sequences from western white pine ( Pinus monticola ), one of the most valuable conifer species endangered by white pine blister rust ( Cronartium ribicola ). In total, 83 P. monticola WRKY (PmWRKY) sequences were identified using degenerate primers targeted to the WRKY domain. A phylogenetic analysis revealed that PmWRKY members fell into four major groups (1, 2a+2b, 2c, and 2d+2e) described in Arabidopsis and rice. Because of high genetic diversity of the PmWRKY family, a modified AFLP method was used to detect DNA polymorphism of this gene family. Polymorphic fragments accounted for 17%–35% of total PCR products in the AFLP profiles. Among them, one WRKY AFLP marker was linked to the major resistance gene (Cr2) against C. ribicola. The results of this study provide basic genomic information for a conifer WRKY gene family, which will pave the way for elucidating gene evolutionary mechanisms in plants and unveiling the precise roles of PmWRKY in conifer development and defense response.

Cultures of seven Daphne species: Daphne caucasica, D. cneorum, D. giraldii, D. retusa, D. jasminea, D. laureola and D. tangutica were established in vitro on MS/WPM based media. Five of the species responded best on MS-based media (D. tangutica, D. laureola, D. caucasica, D. retusa and D. giraldii), while the remaining two species performed best on WPM-based media (D. cneorum, and D. jasminea). Shoot proliferation was achieved from both apical and nodal explants. Shoots were sub-cultured from stock cultures, cut into nodal explants 3–5 cm long and place vertically on basal media supplemented with different concentrations and combinations of cytokinins and auxins. Individual species displayed different responses to the various cytokinins and auxins. Among species, D. jasminea produced the greatest proliferation rate with an average of 7.84 + 0.6 shoots per explant on WPM supplemented with 2.32 μM BA + 0.0045 μM TDZ + 0.054 μM NAA, while the best multiplication rate for the same species grown on the same media supplemented with a single cytokinin (BA) and no auxin was 2.60 + 1.3 shoots per explant. Following multiplication, new shoots transferred to the elongation trails and then 50–100 mm Shoots used for rooting experiments. Increased rooting efficiencies were observed on in vitro-generated shoots with the two-layer medium or dipping methods over when PGRs were uniformly incorporated into the medium. Maximum rooting frequencies (average) ranged from 59% in D. tangutica to 85% in D. jasminea. Following in vitro rooting, rooted shoots immersed in 0.01% solution of humates and planted into a standard horticultural substrate composed and watered weekly with a solution containing half-strength MS salts.

White pine blister rust (WPBR), caused by Cronartium ribicola, is a devastating disease in Pinus monticola and other five-needle pines. Pyramiding a major resistance gene (Cr2) with other resistance genes is an important component of integrated strategies to control WPBR in P. monticola. To facilitate this strategy, the objective of the present study was to identify leucine-rich repeat (LRR) polymorphisms, amplified fragment length polymorphisms (AFLPs), and sequence characterized amplified region (SCAR) markers linked to the western white pine Cr2 (BSA) gene for precise gene mapping. Bulked segregant analysis and haploid segregation analysis allowed the identification of 11 LRR polymorphisms and five AFLP markers in the Cr2 linkage. The closest LRR markers were 0.53 Kosambi cM from Cr2 at either end. After marker cloning and sequencing, AFLP marker EacccMccgat-365 and random polymorphic DNA marker U570–843 were converted successfully into SCAR markers. For a potential application in marker-assisted selection (MAS), these two SCAR markers were verified in two western white pine families. This study represents the first report of LRR-related DNA markers linked to C. ribicola resistance in five-needle pines. These findings may help further candidate gene identification for disease resistance in a conifer species.

In Pinus monticola (Dougl. ex D. Don), the class ten pathogenesis-related (PR10) proteins comprise a family of multiple members differentially expressed upon pathogen infection and other environmental stresses. One of them, PmPR10-1.13, is studied here by investigating its transcriptional regulation in transgenic Arabidopsis plants. For functional analyses of the PmPR10-1.13 promoter, a 1,316-bp promoter fragment and three 5' deletions were translationally fused to the ss-glucuronidase (GUS) reporter gene. The 1,316-bp promoter-driven GUS activity first appeared in hypocotyls and cotyledons in 2- to 3-day-old seedlings. As transgenic plants grew, GUS activity was detected strongly in apical meristems, next in stems and leaves. No GUS activity was detected in roots and in reproductive tissues of flower organs. In adult plants, the PmPR10-1.13 promoter-directed GUS expression was upregulated following pathogen infection and by wounding treatment, which generally mimic the endogenous expression pattern in western white pine. Promoter analysis of 5' deletions demonstrated that two regions between -1,316 and -930, and between -309 and -100 were responsible for the wound responsiveness. By structural and functional comparisons with PmPR10-1.14 promoter, putative wound-responsive elements were potentially identified in the PmPR10-1.13 promoter. In conclusion, PmPR10-1.13 showed properties of a defence-responsive gene, being transcriptionally upregulated upon biotic and abiotic stresses.

Four protein bands of 38, 34, 32 and 25 kDa (designated as Picg5a to Picg5d) were detected specifically with an antibody against a putative PR10 protein Picg1 in Picea glauca. The Picg5 proteins accumulated during cold acclimation in foliage and roots and showed polymorphism in the population. Only one Picg5 protein was expressed in each individual seedling. The Picg5 protein levels were positively correlated with freezing tolerance (R 2=0.6, P

Summary PR-10 is a group of pathognesis-related proteins that are induced by biotic and abiotic stresses. In conifers, PR-10 proteins and their genes were isolated and characterized. In some species, there is a multi-gene family encoding PR-10 proteins. These PR-10 proteins were shown to be up-regulated by pathogens in two conifer pathosystems and were associated with overwintering of conifers. In western white pine, the level of PR-10 protein is associated with frost hardines of white pine needles. Ultrastructural localization revealed that western white pine PR-10 protein is an intracellular protein and is found in chloroplasts of mesophyll and endodermis, and in the stroma. In infected pine needles, the PR-10 protein was bound to the cell surface of the blister rust pathogen. PR-10 genes are organized along two exons intervened by an intron. Homology of PR-10 proteins is higher among five-needle pines than in either Douglas-fir or white spruce. Cloning, sequencing, and functional analysis of PR-10 prom...

To understand the molecular defence response of western white pine to the blister rust pathogen Cronartium ribicola, we have endeavoured to isolate and characterise pathogenesis-related (PR) proteins from western white pine. A full-length cDNA (Pin mTLP) was isolated from a cDNA library constructed from inoculated foliage. BLASTX search results indicated that the sequence shared a high degree of identity with the thaumatin-like proteins (TLPs) of the PR-5 family, and in particular with those of the ‘small-TLP’ subgroup mainly identified in monocots. The mature protein predicted from the cDNA sequence has a molecular mass of 16 kDa and pI of 4.1. Southern blot analysis showed that Pin mTLP is a single-copy gene member of a multi-gene family. Two-dimensional Western blot analysis of total western white pine protein extracts probed with a Douglas-fir anti-TLP antibody detected a major and a minor protein spot of 23 and 17 kDa, respectively. Both 23 and 17-kDa proteins were identified as TLPs by Nanospray MS/MS analysis. The 23-kDa protein was shown to accumulate in canker margins in the bark of infected seedlings indicating that it is locally induced in response to fungal invasion. Both local wounding and methyl jasmonate treatments induced expression of the protein, whereas salicylic acid treatment did not. These results suggest that the 23-kDa TLP plays a role in the molecular defence response of western white pine to wounding and pathogen attack.

Summary Extracellular proteins were extracted from Phellinus weirii infected Douglas-fir (Pseudotsuga menziesii var. menziesii) roots and needles to examine endochitinase activity. Chitinases have been associated with the plant's defence response against fungal attack because they hydrolyse chitin, a structural component of fungal cell walls. Protein separation using sodium dodecyl sulphate-polyacrylamide gel electrophoresis (SDS-PAGE) followed by Western immunoblot analysis using a polyclonal antibody specific to an endochitinase-like protein (ECP) resulted in the detection of up to three polypeptides between 27 and 30 kDa in size. Two-dimensional gel electrophoresis (2-D PAGE) followed by Western immunoblot analysis revealed that the apoplastic fluid contained multiple ECP isoforms with isoelectric points (pIs) ranging from 5.3 to 5.8 and molecular masses of 27–30 kDa. Chitinase activity in needle and root tissues was measured spectrophotometrically using a colorimetric assay. A gel overlay technique using glycol chitin as a substrate for endochitinase was applied to confirm that the ECP antibody detected an enzymatically active protein. The apoplastic fluid collected from P. weirii-infected winter Douglas-fir needles showed anti-freeze activity and seasonal analysis of needle tissue showed some evidence of ECP accumulation in winter months. ECP was distributed systemically throughout the tree. Increased levels of endochitinase activity in the region of P. weirii infection supports a physiological role for ECP in the plant defence response. Resume Les proteines extra-cellulaires ont ete extraites des racines et aiguilles de douglas (Pseudotsuga menziesii var menziesii) infectes par Phellinus weirii (Murr.) Gilbn., pour etudier l'activite endochitinase. Les chitinases ont ete associees aux reactions de defense des plantes contre les attaques fongiques parce-qu'elles hydrolysent la chitine, un composant de la paroi des cellules fongiques. La separation des proteines, realisee par electrophorese en gel de polyacrylamide avec sodium dodecyl sulfate (SDS-PAGE), suivie par une analyse par Western immunoblot en utilisant un anticorps polyclonal specifique d'une proteine de type endochitinase (ECP), a permis la detection de 3 polypeptides de taille comprise entre 27 et 30 kDa. Une electrophorese sur gel en 2-dimensions (2-D PAGE) suivie par une analyse par Western immunoblot a revele que le fluide apoplastique contient de multiples isoformes d'ECP avec des pI dans une gamme de 5.3 a 5.8 et des masses moleculaires de 27 a 30 kDa. L'activite chitinase dans les aiguilles et tissus racinaires a ete mesuree par spectrophotometrie par une methode colorimetrique. Une technique d'overlay utilisant de la chitine glycol comme substrat de l'endochitinase a ete appliquee pour confirmer que l'anticorps ECP avait detecte une proteine active du point de vue enzymatique. Le fluide apoplastique d'aiguilles recoltees en hiver sur des douglas infectes par P. weirii a montre une activite antigel et l'analyse saisonniere des tissus foliaires a montre une certaine accumulation d'ECP pendant l'hiver. L'ECP est repartie de facon systemique dans l'ensemble de l'arbre. Les niveaux accrus d'activite endochitinase dans la zone infectee par P. weirii suggere un role physiologique de l'ECP dans les reactions de defense de la plante. Zusammenfassung Aus Wurzeln und Nadeln von mit Phellinus weirii infizierten Douglasien (Pseudotsuga menziesii var. menziesii) wurden extrazellulare Proteine extrahiert, um die Endochitinase-Aktivitat zu bestimmen. Chitinasen werden mit der pflanzlichen Abwehrreaktion auf Pilzinfektionen in Verbindung gebracht, da sie Chitin, eine Strukturkomponente der pilzlichen Zellwand, hydrolysieren. Die Proteine wurden mit Natrium-Dodecyl-Sulfat-Polyacrylamid-Gelelektrophorese (SDS-PAGE) getrennt, gefolgt von einer Western Immunoblot-Analyse mit einem gegen ein Endochitinase-ahnliches Protein (ECP) spezifischen polyklonalen Antikorper. Hiermit liessen sich bis zu drei Polypeptide zwischen 27-30 kDa nachweisen. Eine zweidimensionale Gelelektrophorese (2-D PAGE) mit anschliessender Western Immunoblot-Analyse ergab, dass die Apoplastenflussigkeit multiple ECP-Isoformen enthielt (mit pIs von 5,3 bis 5,8 und Molekularmassen von 27 bis 30 kDa). Die Chitinase-Aktivitat wurde auch im Nadel- und Wurzelgewebe spektrophotometrisch mit einer Farbreaktion gemessen. Um sicher zu stellen, dass der ECP-Antikorper ein enzymatisch aktives Protein nachwies, wurde eine Gel-Overlay-Methode verwendet, mit Glycolchitin als Substrat fur die Endochitinase. Die Apoplastenflussigkeit der Nadeln von mit P. weirii infizierten Douglasien zeigte in Winterzustand eine Antifrost-Aktivitat, ihre Analyse wahrend des gesamten Jahres ergab aber keine Hinweise auf eine ECP-Anreicherung wahrend der Wintermonate. ECP war systemisch im gesamten Baum enthalten. Die erhohte Endochitinase-Aktivitat in Bereichen mit P. weirii-Infektion lasst auf eine physiologische Rolle von ECP in der Pflanzenabwehr schliessen.

White pine blister rust (WPBR) is caused by the fungus Cronartium ribicola which has five spore stages on two unrelated hosts, the five-needle pines and Ribes spp. Recently, during the molecular analysis of the proteins and genes involved in host-pathogen interaction, the WPBR fungal protein Cro rI was identified in infected white pine tissues. To further characterize Cro rI, an expression cDNA library from poly(A)(+) mRNA of C. ribicola axenic mycelial culture was constructed and immunoscreened and the cDNA was cloned. Sequence analysis indicated an open reading frame of 462 bases, which encodes a protein of 153 amino acid residues with a molecular mass of 16.7 kDa and a predicted isoelectric point (pI) of 8.93. Based on the N-terminal amino acid sequences of Cro rI, the secreted portion of Cro rI protein should be 136 amino acids long with several putative posttranslational modification sites and a molecular mass of 14.8 kDa. The predicted pI for the secreted portion was 9.34. The predicted N-terminal signal peptide was 17 amino acids long. The N-terminal 42-amino acid sequence of the predicted mature protein (secreted portion) was identical to the amino terminal sequence of Cro rI that was previously determined. Southern blot hybridizations indicated that the C. ribicola genome contained at least two copies of the cro rI gene. Isolation of the genomic PCR fragment, which was approximately 400 bp longer than the cDNA, and subsequent cloning and sequencing analyses confirmed that there were three introns within the coding regions. Western immunoblot analyses revealed that Cro rI protein accumulated in large amounts only in the infected white pine tissues while no trace was detectable in the alternate Ribes stage or the five different spores, suggesting a critical role of Cro rI in the haploid stage of the fungus (in pine). The translocation of Cro rI was only found to occur in cankered trees, and not in the young infected seedlings. The implications of Cro rI in pathogenesis are discussed.

The production and characterization of monoclonal antibodies (Mab) to the white pine blis- ter rust (WPBR) fungus (Cronartium ribicola) were described by Ekramoddoullah and Taylor (1996). One of the monoclonal antibodies, Mab 7, detected a major mycelial antigen on blister rust. This mono- clonal antibody did not cross-react with proteins from the white pine host or with proteins from other fun

Pollen germination and tube elongation in Pinus monticola are accompanied by RNA and protein synthesis as shown by the effects of inhibitors such as actinomycin D and cycloheximide, respectively. Pollen grains germinate in the presence of actinomycin D, but further tube elongation is inhibited. This suggests that RNAs needed for germination are already available in the mature ungerminated pollen, but continued tube elongation depends on the synthesis of new RNAs. Using cycloheximide, our results indicate that some proteins essential for germination and tube elongation are not yet available in the mature ungerminated pollen. In P. monticola, it appears that these proteins are synthesized at the onset of pollen germination and during tube elongation. The effects of inhibiting transcription and translation in eight other conifers are the same as in P. monticola, suggesting a common trend. In P. monti-cola, profiles of pollen grains and pollen tubes varied in the expression of at least ten proteins. Based on the stages examined, the protein profiles of 2-day-old tubes appear to be the most variable with some proteins increasing or decreasing in intensity only at this stage. In P. monticola, four proteins (26, 27, 38 and 40 kDa) are differentially expressed during pollen tube development. The most notable is a 26-kDa protein which is specifically expressed in pollen tubes. It is possible that this protein controls a function unique to pollen tubes. This report adds to our knowledge of the regulation of pollen tubes development in conifers. It also offers insights on why development of pollen tubes in conifers takes much longer than in flowering plants.

Ultrathin sections of five spore stages of C. ribicola were incubated with wheat germ agglutinin (WGA), which binds to chitin, followed by an ovomucoid-gold complex, which binds to WGA and examined by TEM. Labelling experiments showed the presence of chitin in all five stages of the fungus, although the distribution of chitin varied among spore stages. Competitive inhibition studies with triacetyl chitotriose showed that WGA bound to cell walls of basidiospores much more strongly than other spore types, requiring a 10-fold increase in concentration over that required for the other spore types to achieve complete inhibition.

Previously, a PR-10 protein Pin m III was described in western white pine. In this study, primers based on cDNA of Pin m III were utilized to obtain the genomic sequence of a Pin m III homologue - Pse m I - in Douglas-fir. A comparative analysis of a deduced amino acid sequence of Pin m III and Pse m I genes indicated about 80% similarity between the two protein sequences, and a consensus 20 amino acid sequence located around the p-loop sequence was used to synthesize a peptide of 20 amino acids. An antibody to this synthetic peptide was able to detect the Pse m I protein in Douglas-fir. The anti-Pse m I antibody was used in a western immunoblot to monitor seasonal variation of the Pse m I in Douglas-fir needles and its level was shown to increase with overwintering of Douglas-fir seedlings. However, unlike the Pin m III, there is no indication that the Pse m I is associated with frost hardiness. Analysis of infected Douglas-fir roots showed a possible trend to up-regulation of Pse m I by pathogens such as the laminated root rot fungus, Phellinus weirii. The expression of Pse m I protein in Douglas-fir seedlings is very low compared to the expression of Pin m III protein in western white pine seedlings. In addition, a light-harvesting complex I protein, PSI-F, was identified in Douglas-fir by N-terminal amino acid sequencing.

Maximum accumulation of Pin m III protein in western white pine (Pinus monticola Dougl. ex D. Don) needles occurred during the winter months. To characterize Pin m III, an expression cDNA library from poly(A)+ mRNA of needles was immunoscreened and the full length cDNA was cloned. An open reading frame of 486 bases encodes a protein of 161 amino acid residues with a molecular mass of 18 kD and a predicted isoelectric point of 5.5. The deduced amino acid sequence had some similarities (37%) with an intracellular pathogenesis-related (PR) protein from garden asparagus (Asparagus officinalis L.) and the major pollen allergen from white birch (Betula verrucosa J. F. Ehrh.), which are members of the ribonuclease-like PR-10 family. Phylogenetic analysis provided circumstantial evidence that Pin m III may be grouped with intracellular PRs from asparagus and potato (Solanum tuberosum L.), while the allergens formed another subgroup. Northern analysis showed that the Pin m III gene was preferentially expressed during cold acclimation with the highest expression in the fall and winter months, preceding the peak of Pin m III protein accumulation. Tissue specificity expression analysis indicated that the gene was strongly expressed in roots and twigs. Higher amounts of the homologous protein (Pin l I) and its transcript accumulated in sugar pine (Pinus lambertiana Dougl.) needles infected with blister rust compared with healthy needles.

Previously we showed that a white pine protein Pin m III (a member of PR10 family of pathogenesis-related proteins) is up-regulated by infection in the white pine blister rust pathosystem. In this study, a blister rust fungal protein, Cro r I, which is similar in size to Pin m III (19 kDa), was detected in the infected white pine tissues. The N-terminal amino acid sequence of Cro r I isolated from infected pine foliage and from fungal mycelia was identical. Rabbit antibody was prepared to a synthetic N-terminal peptide and was purified by immunoaffinity. The purified antibody was used in a Western immunoblot to quantify the amount of Cro r I in various tissues. In western white pine seedlings the amount of Cro r I was significantly (p < 0.0001) higher in infected tissues of cankered seedlings than the infected tissues of resistant seedlings. In sugar pine seedlings, the amount of Cro r I was also significantly (p < 0.01) higher in infected tissues of susceptible seedlings than in resistant seedlings. Furthermore, Cro r I is secreted by the blister rust fungus and was found to be translocated to the healthy tissues of cankered white pines. Cro r I is a major protein that could be extracted from infected foliage by vacuum infiltration. The level of Cro r I detected in the mycelium of different isolates varied. The cDNA of Cro r I was isolated by reverse transcription - polymerase chain reaction. Comparison of the DNA sequence and the deduced protein sequence with data bases revealed that it is a previously undescribed protein. The calculated molecular weight from the deduced protein sequence of Cro r I was 16.7 kDa and the calculated isoelectric point was 9.55. Protein sequence analysis showed that Cro r I has two potential N-linked glycosylation sites in its sequence.Key words: translocation, elicitor, antibody, amino acid sequence.

Summary In order to differentiate among Phellinus pini, Inonotus tomentosus and Inonotus circinatus a polyclonal antibody was raised to a N-terminal part of 25-kDa P. pini-specific protein. The specificity of the polyclonal antibody produced against a synthetic N-terminal peptide of this protein was investigated for diagnostic purposes using Western immunoblot, indirect enzyme-linked immunosorbent assay (ELISA), and inhibition ELISA techniques. The N-terminal synthetic peptide, used as the immunogen, was found to be more than 80% pure by reverse-phase high-performance liquid chromatography. Following immunization, antisera were collected at three different time intervals. The antibody molecules were purified from the crude antisera using immunoaffinity gel chromatography. Following one-dimensional sodium dodecylsulfate-polyacrylamide gel electrophoresis, Western immunoblot analysis showed that the P. pini I polyclonal-antibody detected the immunogen, the 25-kDa protein, in all but one of the P. pini isolates examined, but in none of the isolates of the nontarget species I. tomentosus and I. circinatus. Nevertheless, cross-reactivity was a problem because the P. pini I polyclonal-antibody also recognized bands at other molecular weights in nearly all of the isolates of the other species tested. With the indirect ELISA the P. pini isolates tended to have higher affinity for the polyclonal antibody than the nontarget species, but some cross-reactivity did occur. Inhibition ELISAs, performed over a range of soluble antigen concentrations (1.56–400 ng/100 μl), failed to show a clear distinction between P. pini and the two Inonotus spp. The low level of cross-reactivity observed for I. tomentosus isolate 52 (9%) was also apparent in the indirect ELISA analysis. All three assays indicated that P. pini isolate 41 was the most antigenic. Despite cross-reactivity, the antibody is useful in Western immunoblots for the diagnosis of most P. pini isolates.

Proteins were extracted from a Canada- wide collection of Inonotus tomentosus, L circinatus and jR pini isolates grown in liquid culture. One-di- mensional (1-D) and two-dimensional (2-D) protein profiles were made and compared. Phellinus pini ap? peared more closely related to /. tomentosus than did L circinatus. A dendrogram based on average root- mean-square distance between clusters distinctly sep? arated I. circinatus into eastern and western groups. There were only two proteins from 1-D gel analysis that possibly could be used for antibody production to distinguish R pini, and none for I. tomentosus or /. circinatus. For the three species, there were possi? bly 18 proteins which could be eluted from 2-D gels for developing distinguishing antibodies. the three fungi produce macroscopically similar brown mats. Microscopically, /. tomentosus and P pini mycelia differ by a single character, the presence or absence of chlamydospores (Nobles, 1965). Inonotus tomentosus usually can be recognized readily by co- pious production of chlamydospores, but in some iso? lates they are rare. In P. pini chlamydospores are ab? sent or extremely rare (Hunt, unpub data). The P pini isolates used in this study could be classified as P. vorax (Harkness) Cerny. However, even this seg- regate has a large host range (Cerny, 1985), such that one would suspect within-species variability. Methods are needed for forest surveys to distin? guish among the decays produced by these fungi, and to facilitate identification of these species in cul? ture. As a first step to achieving these goals, the ob? jective of this study was to determine if there are unique proteins in each of these species, particularly those derived from Canadian Picea spp., that could have potential for the development of an antibody- based diagnostic method.

Recently, a western white pine protein, Pin m III, was shown to be associated with overwintering and frost hardiness of western white pine foliage. To examine whether Pin m III is directly involved in frost hardiness by functioning as an antifreeze protein, work is underway to clone the gene encoding this protein and to assess the function of this gene in freezing tolerance by incorporating the gene in a test plant, such as tobacco. Here, we examined in more detail, by SDS-PAGE and also by two dimensional gel electrophoresis, the seasonal variation of additional proteins in western pine foliage. SDS-PAGE analysis of three seedlots showed that different proteins reached a maximum level in different months, although most proteins (5 to 11) reached a maximum level in winter months (December, January and February). The 2-D gel analysis of foliage sampled on three harvest dates (October, January and April) of one seedlot revealed a seasonal variation of a large number proteins (76 to 184). Of the seasonally varied proteins, the amino terminal sequence of several proteins including Pin m III was determined. One of the sequences was identified by homology to that of the small subunit of ribulose biphosphate carboxylase, whose level increased substantially from fall to spring. The amino terminal sequence of Pin m III had 89% homology to a sugar pine protein, Pin l I. The anti-photosystem II antibody was used to monitor the annual variation of the extrinsic 23-kDa photosystem II protein. The level of the extrinsic 23-kDa photosystem II protein decreased slowly as fall progressed and reached its lowest level in December and then increased in early spring indicating that this variation is due to photosynthetic activity of the foliage during the season.

A 19-kDa protein of sugar pine (named Pinl I; i.e., protein I of Pinuslambertiana Dougl.) was detected in increasing amounts in the fall. This protein was separated by SDS–PAGE and also by two-dimensional gel electrophoresis. Pinl I was composed of two acidic isoforms. This protein was subjected to N-terminal amino acid sequence analysis. The two isoforms had an identical N-terminal amino acid sequence. The N-terminal peptide was synthesized and purified, and the purity of the synthetic peptide was greater than 95%. The peptide was conjugated to a carrier protein, keyhole limpet hemocyanin (KLH). Rabbits were immunized with peptide–KLH and the antipeptide antibody was purified from the crude antisera by immunoaffinity chromatography. The antibody was shown to bind specifically to PinI I. This anti-Pin I I antibody was used in a Western immunoblot to detect the homologues of Pin1 1 in two other five-needled pines: western white pine (Pinusmonticola Dougl.; named Pinm III) and eastern white pine (Pinusstrobus L.). The antibody was also used to monitor the seasonal variation of Pinm III in western white pine needles. Pinm III was shown to be associated with overwintering of western white pine seedlings. A significant correlation was observed between the frost hardiness of western white pine foliage and the content of Pinm III.

The proteomic profiles of primary needles from Cr2-resistant and cr2-susceptible Pinus monticola seedlings were analysed post Cronartium ribicola inoculation by 2-DE. One hundred-and-five protein spots exhibiting significant differential expression were identified using LC-MS/MS. Functional classification showed that the most numerous proteins are involved in defence signalling, oxidative burst, metabolic pathways, and other physiological processes. Our results revealed that differential expression of proteins in response to C. ribicola inoculation was genotype- and infection-stage dependent. Responsive proteins in resistant seedlings with incompatible white pine blister rust (WPBR) interaction included such well-characterized proteins as heat shock proteins (HSPs), reactive oxygen species (ROS) scavenging enzymes, and intermediate factors functioning in the signal transduction pathways triggered by well-known plant R genes, as well as new candidates in plant defence like sugar epimerase, GTP-binding proteins, and chloroplastic ribonucleoproteins. Fewer proteins were regulated in susceptible seedlings; most of them were in common with resistant seedlings and related to photosynthesis among others. Quantitative RT-PCR analysis confirmed HSP- and ROS-related genes played an important role in host defence in response to C. ribicola infection. To the best of our knowledge, this is the first comparative proteomics study on WPBR interactions at the early stages of host defence, which provides a reference proteomic profile for other five-needle pines as well as resistance candidates for further understanding of host resistance in the WPBR pathosystem.

The protein content in the plant apoplast is believed to change dramatically as a result of host defense response upon infection with various pathogens. In this study, six novel thaumatin-like proteins (TLPs) were identified in western white pine (Pinus monticola) needle apoplast by a proteomic strategy using two-dimensional protein electrophoresis followed by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry. Sequent cDNA cloning found that ten P. monticola TLP genes (PmTLP-L1 to -L6 and -S1 to -S4) were expressed in various tissues. Phylogenetic analysis demonstrated that these PmTLP genes belong to a large, complex, and highly diverse plant TLP family. Quantitative reverse transcription-polymerase chain reaction (RT-qPCR) using gene-specific primer pairs showed that each PmTLP gene exhibited a characteristic pattern of mRNA expression based on their unique organ distribution, seasonal regulation, and response to abiotic and biotic stresses. A time-course analysis at the early stages of infection by white pine blister rust pathogen Cronartium ribicola revealed that a coordinated upregulation of multiple PmTLP genes was involved in P. monticola major gene (Cr2) resistance. The structural and expressional differentiations suggest that the PmTLP family may contribute to host defense as well as other mechanism.

In the present study, in a candidate gene approach, a class IV chitinase gene (PmCh4A) of pathogenesis-related family three was cloned and characterized in western white pine (Pinus monticola). PmCh4A chitinase expression in the different organs of healthy seedlings was below levels detectable by western immunoblot analysis using an antibody raised against PmCh4A protein. However, a 27-kDa isozyme of PmCh4A accu mulated in both susceptible and slow-canker-growth (SCG) resistant seedlings after infection by Cronartium ribicola. As with fungal infection, the application of a signal chemical (methyl jasmonate) and a protein phosphatase 1 and 2A inhibitor (okadaic acid) increased the PmCh4A protein accumulation. Furthermore, another 26-kDa isozyme was expressed specifically in SCG resistant seedlings, providing a potential tool for marker-assisted selection in forest breeding. Wounding treatment also induced expression of the protein. These data suggest that the class IV chitinase PmCh4A is involved in the defense response of western white pine to infection and abiotic stresses.

In western North America, Douglas-fir (Pseudotsuga menziesii) is the most economically important conifer species susceptible to laminated root rot caused by Phellinus weirii. While attempting to internally sequence an endochitinase found to be up-regulated in P. weirii-infected Douglas-fir roots, we obtained overlapping peptide fragments showing 28% similarity with a PR-5 thaumatin-like protein (TLP) designated PmTLP (Pm for Pseudotsuga menziesi). A rabbit polyclonal antibody was reared against a synthetic peptide composed of a 29-amino-acid-long, conserved, internal sequence of PmTLP and purified by immunoaffinity. Western immunoblot analysis of infected roots of 24-year-old coastalfir showed significantly higher amounts of PmTLP (P < 0.01) closest to the point of P. weirii inoculation and infection than in uninfected regions of the same root. The antibody was also used to screen for PmTLP in roots of 25-year-old interior Douglas-firs naturally infected with a related pathogen, Armillaria ostoyae, and results showed significantly higher levels of PmTLP in bark tissues adjacent to infection (P < 0.05) than in uninfected tissue. Using polymerase chain reaction (PCR)-based cloning, the cDNA of PmTLP was shown to have a 702-bp open reading frame with a signal peptide cleavage site at 155 bp corresponding to a 29-amino-acid-long residue prior to the start of the N-terminal. Based on the deduced amino acid sequence, the molecular mass of the putative PmTLP was calculated to be 21.0 kDa with an isoelectric point of 3.71. Alignment analysis of PmTLP cDNA with a representative genomic DNA PCR sequence showed presence of one intron of variable size, within the coding region. The induction of PmTLP at the site of root infection and its presence in needle tissue suggests a general role for this protein in adaptation to stress and may be part of an integrated defense response initiated by the host to impede further pathogen spread.

We have been working on proteins that are involved in the defense response of western white pine (WWP) (Pinus monitcola) to the blister rust fungus Cronartium ribicola. Our objective was to identify candidate genes that could be used for improving resistance of WWP to this rust pathogen. During proteomic analysis of bark proteins extracted from WWP trees exhibiting slow-canker-growth (SCG) resistance, a 10.6-kDa peptide, termed Pm-AMP1, was found to be enriched at the receding canker margin. The cDNA encoding this peptide was cloned and characterized. A BLASTX search revealed that the Pm-AMP1 encoded by its cDNA has a 50% homology with MiAMP1, a broad-spectrum antifungal protein isolated from Macadamia integrifolia. Based on the deduced amino acid sequence, an antibody was produced against the Pm-AMP1. Immunochemical quantification of the Pm-AMP1 in bark samples of susceptible WWP trees revealed this protein to be barely detectable in the cankered tissues, but occurring in higher concentrations in healthy tissues away from canker margins. Foliage of SCG-resistant trees contained higher concentrations of the Pm-AMP1 than foliage from susceptible cankered trees. Both wounding and methyl jasmonate treatment of WWP needles induced the expression of this protein, further supporting its putative role as a defense response protein.

To investigate disease resistance gene analogs (RGAs) encoding coiled-coil-nucelotide-binding site-leucine-rich repeats (CC-NBS-LRR) proteins in western white pine, degenerate primers targeting the conserved motifs in the NBS domain were designed to amplify RGAs from genomic DNA and cDNA. Sixty-one distinct RGAs were identified with identities to well-known R proteins of the CC-NBS-LRR subfamily. These RGAs exhibited variation of putative amino acid sequences from 13% to 98%, representing a complex CC-NBS-LRR subfamily. A phylogenetic tree constructed from the amino acid sequence alignment revealed that these 61 RGAs were grouped with other CC-NBS-LRR members from angiosperms, and could be further divided into six classes with an identity threshold of 68%. To map RGAs, RGA polymorphisms and a modified amplified fragment length polymorphism (AFLP) method with incorporated sequences from the NBS domain were used to reveal NBS or NBS-AFLP markers. RGA polymorphism study revealed that three off the identified RGAs were not linked to the Cr2 gene imparting resistance to white pine blister rust. However, the AFLP strategy, using bulk segregant analysis (BSA) and haploid segregation analysis, identified 11 NBS-AFLP markers localized in the Cr2 linkage, the closest two to the gene being 0.41 cM and 1.22 cM away at either side. Eight of these markers showed significant amino acid sequence homologies with RGAs.

Liu, J.-J., Ekramoddoullah, A. K. M., Hunt, R. S., and Zamani, A. 2006. Identification and characterization of random amplified polymorphic DNA markers linked to a major gene (Cr2) for resistance to Cronartium ribicola in Pinus monticola. Phytopathology 96:395-399. DNA markers tightly linked to resistance (R) genes provide a very powerful tool for both marker-assisted selection in plant breeding and positional cloning of R genes. In the present study, a linkage of random amplified polymorphic DNA (RAPD) markers to the single dominant gene (Cr2) for resistance to white pine blister rust fungus (Cronartium ribicola) was investigated in western white pine (Pinus monticola). A mapping population of 128 individual megagametophytes was generated from seeds of a heterozygous resistant tree (Cr2/cr2), and the corresponding seedlings of each megagametophyte were subjected to the test of phenotype segregation by inoculation with C. ribicola. Bulked segregant analysis and haploid segregation analysis identified eight robust RAPD markers linked to Cr2. This constitutes the first Cr2 genetic linkage map spanning 84.7 cM with four markers only 3.2 cM from Cr2. One sequence (U2561385) of these linked markers was significantly similar to the Ty3/gypsylike long terminal direct repeats retrotransposons. Another marker, U570843, had no significant similarity to any entry in either GenBank or the loblolly genomics data bank. As presumed that the average physical distance per centimorgan is about 10 Mb in P. monticola, it is probably unrealistic to use these DNA markers for positional cloning of the Cr2 gene.

Several aspects of the host–pathogen interaction between Douglas-fir (Pseudotsuga menziesii) and the fungal pathogen Phellinus sulphurascens were investigated in an in vitro inoculation system using young seedlings and fungal mycelia. Light microscopy confirmed that P. sulphurascens mycelia can successfully penetrate host epidermal cells within 3 days postinoculation (dpi). Extensive fungal colonization and cortical cell decay occurred within 14 dpi. Western immunoblot studies showed significant upregulation (five to sixfold) of four specific pathogenesis-related (PR) proteins in infected roots. These proteins were a Douglas-fir thaumatin-like protein (PmTLP), an endochitinase protein (ECP), a Douglas-fir PR10 (DF-PR10) protein (PsemI), and a 10.6-kDa antimicrobial peptide (PmAMP1). The highest accumulation of PmTLP and PmAMP1 occurred at 12 dpi, whereas accumulations of the ECP and DF-PR10 proteins peaked at 7 dpi. For both inoculated and control Douglas-fir seedlings, only one of the four PR proteins, PmAMP1, was clearly detectable in needles. Immunolocalization experiments using fluorescein isothiocyanate-conjugated secondary antibodies confirmed accumulation of all four PR proteins mainly in and around cell walls of root cortical tissues. Overall, the highest immunofluorescence was observed in infected roots at 12 dpi, whereas labeling in control roots was negligible at all sample times. The ECP produced the highest fluorescence; the DF-PR10 the lowest. Upregulation and localization of these PR proteins in cortical tissues of inoculated roots suggest that they play a defensive role in response to infection by P. sulphurascens. This in vitro inoculation system will facilitate further proteomic and genomic studies of this important pathosystem.

Interactions between roots of Douglas-fir (DF; Pseudotsuga menziesii ) seedlings and the laminated root rot fungus Phellinus sulphurascens were investigated using scanning and transmission electron microscopy and immunogold labelling techniques. Scanning electron micrographs revealed that P. sulphurascens hyphae colonize root surfaces and initiate the penetration of root epidermal tissues by developing appressoria within 2 d postinoculation (dpi). During early colonization, intra- and intercellular fungal hyphae were detected. They efficiently disintegrate cellular components of the host including cell walls and membranes. P. sulphurascens hyphae penetrate host cell walls by forming narrow hyphal tips and a variety of haustoria-like structures which may play important roles in pathogenic interactions. Ovomucoid–WGA (wheat germ agglutinin) conjugated gold particles (10 nm) confirmed the occurrence and location of P. sulphurascens hyphae, while four specific host pathogenesis-related (PR) protein antibodies conjugated with protein A–gold complex (20 nm) showed the localization and abundance of these PR proteins in infected root tissues. A thaumatin-like protein and an endochitinase-like protein were both strongly evident and localized in host cell membranes. A DF-PR10 protein was localized in the cell walls and cytoplasm of host cells while an antimicrobial peptide occurred in host cell walls. A close association of some PR proteins with P. sulphurascens hyphae suggests their potential antifungal activities in DF roots.

We carried out a comparative proteomic study to explore the molecular mechanisms that underlie the defense response of Douglas-fir (DF, Pseudotsuga menziesii) to laminated root rot, a disease caused by Phellinus sulphurascens. 2-DE was conducted on proteins extracted from roots of laboratory-grown, young DF seedlings inoculated with P. sulphurascens. A total of 1303 proteins was detected in 7 dpi infected and uninfected root samples. Among these 1303 proteins, 277 showed differential expression that was statistically significant (p0.05). Of these 277 proteins, 74 upregulated and 85 downregulated proteins showed at least a two-fold change from controls. Forty seven upregulated and 23 downregulated proteins were selected to be excised and analyzed using LC-MS/MS followed by peptide matching. Our results indicate that the major proteins differentially expressed in P. sulphurascens-infected DF seedlings include those in the following functional groups: disease/defense (27%), metabolism (16%), transcription factors (11%), signal transduction (10%), secondary metabolism (7%) and energy (4%). A number of additional proteins involved in cell structure (3%) and protein synthesis (3%) were also identified. By providing an initial database of candidate pathogenesis-related proteins for the DF-Phellinus sulphurascens pathosystem the results of this study will enable future detailed investigation of gene expression and function.

Analysis by sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) of crude extracts of disease-free and Didymascella thujina-infected foliage of western red-cedar revealed differences in several protein bands and suggests that distinct proteins of D. thujina origin can be identified by SDS-PAGE.

Proteins of the pathogenesis-related (PR)-10 family are induced in many plants by phytopathogens and environmental stresses. A multi-gene family of PR10 proteins has previously been found in the genome of western white pine (Pinus monticola Dougl. ex D. Don). We isolated two novel subfamilies of PR10 cDNAs (PmPR10-2 and PmPR10-3) from P. monticola that are distinct from other PR10 genes (PmPR10-1.1-1.14) reported from the same species. The PmPR10 proteins are grouped in three subfamilies based on similarity in amino acid sequences. The sequence identities of PmPR10 proteins are much higher among members within a subfamily than among members of different subfamilies (86-99% versus 59-68%). Induction of both PmPR10-2 and PmPR10-3 mRNAs was detected by reverse transcriptase-polymerase chain reaction (RT-PCR) in needles in response to wounding treatment. PmPR10-3 was also expressed in needles during cold acclimation in winter. Transcript levels of both PmPR10-2 and PmPR10-3 were less than the detectable levels of constitutive expression in roots, stems and vegetative shoots, whereas PmPR10-1.10 mRNA of subfamily I was expressed at various levels. Phylogenetic analysis showed that PmPR10 and PR10 proteins from other conifers are grouped within one clade that is distinct from that of angiosperm PR10 proteins. In the conifer monophyletic group, PR10 sequences diversify into three distinct clusters. Among these three clusters, some PR10 proteins from single conifer species showed greater divergence distances than sequences from other conifer species, suggesting that, within the conifers, the multi-gene family underwent great diversification during evolution. Based on ratios of nonsynonymous to synonymous nucleotide substitutions (Ka/Ks), we speculate that positive selection resulted in the divergence of PmPR10 subfamilies I and III. Possible mechanisms and significance of PR10 gene evolution are discussed.

We compared bark proteins from four contrasting (blister rust-resistant versus susceptible) half-sib seedling pairs of western white pine (Pinus monticola D. Don). Pooled proteins from resistant and susceptible groups (four trees per group) were separated by two-dimensional gel electrophoresis, silver stained, and analyzed with the aid of a laser scanner interfaced with a computerized gel documentation system. Qualitative and quantitative protein differences were observed between resistant and susceptible groups. The number of proteins unique to a group was greater in the susceptible category than in the resistant category. Biosynthesis of some common proteins was enhanced near lesioned areas of susceptible seedlings. Many proteins shared similar charge and mass characteristics with those of pathogenesis-related (PR) proteins. Two protein bands were isolated and partially characterized by N-terminal amino acid sequencing: a 10.6-kDa band that was selectively enriched in all resistant individuals, and a 26.0-kDa band that was enriched in some susceptible individuals. The significance of these protein differences and the possible use of selected proteins as disease or resistance markers are discussed.

Isolation of PinmIII cDNA homologues from white spruce tissues required a rigorous RNA extraction protocol developed following assessment of three previously reported conifer RNA extraction protocols. Total RNA was extracted via several purification steps designed to minimize binding of phenolics to nucleic acids and was then subjected to caesium chloride ultra-centrifugation. This procedure produced consistently high-quality, intact RNA from both needles and roots with spectrophotometric ratios of approximately 2.0 for both 260/280 nm and 260/230 nm. Total RNA was obtained from the roots of cold-hardened white spruce seedlings for cDNA library construction. More than 2 million recombinant phage particles were generated from 5 microg of a poly(A)+RNA fraction, and ca. 1.3 million cDNA particles were amplified for storage. Approximately 500,000 primary recombinant clones were screened with an heterologous PinmIII cDNA sequence yielding a unique clone, picgl, that was very similar to members of the PR10 gene family.

We report here the isolation and characterization of a novel PR10 gene, PmPR10-1.14, from western white pine (Pinus monticola Dougl. ex. D. Don). The PmPR10-1.14 gene encodes a polypeptide exhibiting high similarity with other members of the PR10 family and corresponds to one of six isoforms immunodetected in the roots of western white pine. Northern blot and western immunoblot analyses showed that expression of the PR10 gene family, including PmPR10-1.14, was detected in vegetative tissues constitutively, but not in developing reproductive organs. RT-PCR with gene-specific primers showed that the transcript of PmPR10-1.14 gene was found only in lateral roots and needles during growth. To study PR10 gene regulation at the cellular level, PmPR10-1.14 promoter was fused to the beta-glucuronidase (GUS) report gene, and analyzed for transient and stable gene expression. The transient expression assays in agroinfiltrated tobacco leaves indicated that the core promoter of PmPR10-1.14 gene resided in the sequence from -101 to +69 relative to the first nucleotide of PR10 cDNA. Furthermore, the promoter region from -311 to -101 acted as an enhancer, and the region from -506 to -311 as a silencer. Fluorometric GUS assays of transgenic tobacco plants demonstrated that the longest promoter of 1675 bp directed GUS expression constitutively at high levels in the roots of mature plants, but expression levels were too low to be detectable in other organs in histochemical assays. Histochemical localization analysis showed that PmPR10-1.14 promoter directed a tissue-specific expression exclusively during the initiation and development of the lateral roots. The distal 5' deletion of the promoter to -311 did not decrease the expression level significantly in the roots, suggesting that the cis-regulatory elements necessary for a high level of gene expression reside in the proximal fragment from -311 to +69. As one striking feature, PmPR10-1.14 promoter contains two copies of direct repeated sequences as long as 281 bp at its distal 5' region. Deletion of one copy (-1326 to -1045) or both copies (-1675 to -1045) of the repeated sequences increased gene expression significantly in leaves and stems, which was regulated developmentally. Further deletion to -820 erased the increased gene expression in leaves and stems. These experiments revealed that the root-specific expression of PmPR10-1.14 gene is mediated by different promoter regions with both negative and positive regulatory mechanisms in transgenic tobacco plants.

Western white pine ( Pinus monticola Dougl. ex. D. Don., WWP) shows genetic variation in disease resistance to white pine blister rust ( Cronartium ribicola). Most plant disease resistance (R) genes encode proteins that belong to a superfamily with nucleotide-binding site domains (NBS) and C-terminal leucine-rich repeats (LRR). In this work a PCR strategy was used to clone R gene analogs (RGAs) from WWP using oligonucleotide primers based on the conserved sequence motifs in the NBS domain of angiosperm NBS-LRR genes. Sixty-seven NBS sequences were cloned from disease-resistant trees. BLAST searches in GenBank revealed that they shared significant identity to well-characterized R genes from angiosperms, including L and M genes from flax, the tobacco N gene and the soybean gene LM6. Sequence alignments revealed that the RGAs from WWP contained the conserved motifs identified in angiosperm NBS domains, especially those motifs specific for TIR-NBS-LRR proteins. Phylogenic analysis of plant R genes and RGAs indicated that all cloned WWP RGAs can be grouped into one major branch together with well-known R proteins carrying a TIR domain, suggesting they belong to the subfamily of TIR-NBS-LRR genes. In one phylogenic tree, WWP RGAs were further subdivided into fourteen clusters with an amino acid sequence identity threshold of 75%. cDNA cloning and RT-PCR analysis with gene-specific primers demonstrated that members of 10 of the 14 RGA classes were expressed in foliage tissues, suggesting that a large and diverse NBS-LRR gene family may be functional in conifers. These results provide evidence for the hypothesis that conifer RGAs share a common origin with R genes from angiosperms, and some of them may play important roles in defense mechanisms that confer disease resistance in western white pine. Ratios of non-synonymous to synonymous nucleotide substitutions (Ka/Ks) in the WWP NBS domains were greater than 1 or close to 1, indicating that diversifying selection and/or neutral selection operate on the NBS domains of the WWP RGA family.

Protein was extracted from root bark of 11- and 25-year-old interior Douglas-fir (Pseudotsuga menziesii (Mirb.) Franco) trees that were naturally infected with Armillaria ostoyae (Romagnesi) Herink. The proteins were separated by sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE). Root bark tissue adjacent to infected areas had a significantly higher protein concentration than healthy tissue (P < 0.05), whereas the protein concentration of infected tissue was consistently lower (P < 0.05) than that of healthy tissue. The SDS-PAGE profiles of healthy, infected, and adjacent-to-infected root bark tissues revealed significant differences in concentrations of a 29.3-kDa protein. The N-terminal amino acid sequence of the 29.3-kDa protein displayed significant homology (P = 0.013) to a basic endochitinase. Use of a polyclonal antibody raised against the 29.3-kDa putative endochitinase-like protein (ECP) indicated differences in the quantities of ECP in healthy roots compared with roots infected with A. ostoyae in 11- and 25-year-old interior Douglas-fir trees. The antibody was also used to screen for the presence of the 29.3-kDa protein in roots of 24-year-old coastal Douglas-fir (Pseudotsuga menziesii var. menziesii) trees that were artificially inoculated with and colonized by Phellinus weirii (Murr.) Gilbn. The amount of ECP was elevated in root bark of coastal Douglas-fir in response to P. weirii infection, although in lower quantities relative to those found in the A. ostoyae-interior Douglas-fir pathosystem. The sequence homology of the ECP with a basic chitinase, together with its increased synthesis in response to two fungal pathogens, indicate a possible role for this protein in the defense of Douglas-fir against fungal pathogens.

Pb2+ and Zn2+ inhibition of photosystem II (PSII) activity was reported to be mediated via displacement of native inorganic cofactors (Cl−, Ca2+ and Mn2+) from the oxygen evolving complex, OEC [Rashid and Popovic (1990) FEBS Lett. 271, 181–184; Rashid et al. (1991) Photosynth. Res. 30, 123–130]. Since the binding sites of these cofactors are protected by a shield of three extrinsic polypeptides (17, 23 and 33 kDa), we investigated whether these metal ions affect the extrinsic polypeptide shield of OEC. By immunoblotting with antibodies recognizing the 23 and 33 kDa polypeptides, we showed that both the metal ions significantly dissociated the 23 kDa (+17 kDa) polypeptide, and partially dissociated the 33 kDa. Ca2+, one of the important inorganic cofactors of oxygen evolution, strongly prevented the dissociating action of Pb2+ but did not prevent the action of Zn2+. The probable molecular mechanism of action of Pb2+ and Zn2+ on PSII OEC is discussed.

A method is described for extracting needle proteins from mature western white pine (Pinus monticola D. Don) trees. Extracted proteins were separated into 26 components by sodium dodecyl sulfate polyacrylamide gel electrophoresis. The predominant protein component (32-39%) had a molecular weight of 57 kDa. The second most predominant protein component (14-25%) had a molecular weight of 16 kDa. The amino acid composition of the twenty-six protein components was determined and a few selected proteins were subjected to further amino acid sequence analysis. Of these, two proteins, designated as Pin m I and Pin m II, were identified by sequence homology with other Photosystem II proteins. The Pin m I and Pin m II proteins had molecular weights of 22.6 kDa and 23.4 kDa, respectively. Pin m I had a much higher proline content than Pin m II.

Background Phellinus sulphurascens is a fungal pathogen that causes laminar root rot in conifers, one of the most damaging root diseases in western North America. Despite its importance as a forest pathogen, this fungus is still poorly studied at the genomic level. An understanding of the molecular events involved in establishment of the disease should help to develop new methods for control of this disease. Results We generated over 4600 expressed sequence tags from two cDNA libraries constructed using either mycelia grown on cellophane sheets and exposed to Douglas-fir roots or tissues from P. sulphurascens-infected Douglas-fir roots. A total of 890 unique genes were identified from the two libraries, and functional classification of 636 of these genes was possible using the Functional Catalogue (FunCat) annotation scheme. cDNAs were identified that encoded 79 potential virulence factors, including numerous genes implicated in virulence in a variety of phytopathogenic fungi. Many of these putative virulence factors were also among 82 genes identified as encoding putatively secreted proteins. The expression patterns of 86 selected fungal genes over 7 days of infection of Douglas-fir were examined using real-time PCR, and those significantly up-regulated included rhamnogalacturonan acetylesterase, 1,4-benzoquinone reductase, a cyclophilin, a glucoamylase, 3 hydrophobins, a lipase, a serine carboxypeptidase, a putative Ran-binding protein, and two unknown putatively secreted proteins called 1 J04 and 2 J12. Significantly down-regulated genes included a manganese-superoxide dismutase, two metalloproteases, and an unknown putatively secreted protein called Ps0058. Conclusions This first collection of Phellinus sulphurascens EST sequences and its annotation provide an important resource for future research aimed at understanding key virulence factors of this forest pathogen. We examined the expression patterns of numerous fungal genes with potential roles in virulence, and found a collection of functionally diverse genes that are significantly up- or down-regulated during infection of Douglas-fir seedling roots by P. sulphurascens. Electronic supplementary material The online version of this article (doi:10.1186/1471-2164-15-603) contains supplementary material, which is available to authorized users.