Phytophthora captiosa sp. nov. and P. fallax sp. nov. causing crown dieback of Eucalyptus in New Zealand

A locally severe crown disease of exotic plantation Eucalyptus trees has been recorded periodically in New Zealand since 1986. Symptoms include leaf spots, petiole infection and twig and small branch lesions. Outbreaks of disease are episodic and individual trees may show marked variation in crown symptoms ranging from unaffected to total defoliation. Two previously unknown species of Phytophthora are associated with the disease. These are described and formally designated here as P. captiosa, from Eucalyptus botryoides and E. saligna; and P. fallax, from E. delegatensis, E. fastigata, E. nitens and E. regnans. Both P. captiosa and P. fallax have non-papillate, non-caducous sporangia and both are self-fertile. Phylogenetic analysis on the basis of ITS rDNA sequence data indicates they are closely related to each other but evolutionarily distant from the majority of described Phytophthora taxa. They share a common ancestor with another assemblage of Phytophthora lineages that includes P. insolita, P. macrochlamydospora and P. richardiae. Sporulation of P. captiosa and P. fallax has not been observed in the field. The mode of infection and spread of these non-caducous Phytophthora species in the eucalypt tree canopy remains unknown. This issue, and the possible geographic origins of these two Phytophthora species are discussed.     

A J E Smith,M.A., D.Phil., D.Sc. (1935–2012)

Abstract

Based on morphology and phylogenetical analyses of nrITS sequences, the Andean endemic Plagiochila (Jamesoniella) dependula is placed in Plagiochila sect. Fuscoluteae. Perianths, oil bodies and sporophytes are described for the first time. Morphologically, P. dependula is characterized by entire, dorsally mostly shortly decurrent, laterally appressed, reniform leaves which are covered by irregular papillae and membranous wax platelets, papillose oil bodies, intercalary androecia with opposite bracts that overlap dorsally, a plagiochilid perianth with an entire mouth, a 250 μm thick capsule wall with thickenings in all layers, large 1–4 celled spores, and bispiral elaters. Morphotypes of Plagiochila fuscolutea with laterally appressed leaves differ from P. dependula by an at least moderately decurrent, broad dorsal leaf base, a ±smooth upper leaf surface, and by its often toothed leaf apices. Plagiochila wolframii is placed in the synonymy of P. fuscolutea. Maximum likelihood and parsimony analyses of 29 Plagiochila ITS sequences resolve P. dependula in a well-supported clade with several other representatives of P. sect. Fuscoluteae. Branch lengths within sect. Fuscoluteae point to a sudden diversification. Accessions of P. heterophylla s.str. from Great Britain (formerly known as P. atlantica) and Costa Rica form an unsupported monophyletic lineage.     

Systematic revision of the genus Phycodrys (Delesseriaceae,Rhodophyta) from New Zealand,with the descriptions of three new species,P. novae-zelandiae sp. nov., P. franiae sp. nov. and P. adamsiae sp. nov.

Two species of Phycodrys, Phycodrys quercifolia (Bory) Skottsberg and Phycodrys profunda E.Y.Dawson were previously recorded from New Zealand. However, an examination of Phycodrys collections from the New Zealand region showed that all were morphologically different from P. quercifolia (Type locality: the Falkland Islands) and P. profunda (Type locality: CA, USA). RbcL sequence analyses established that the New Zealand Phycodrys species formed a natural assemblage within the genus, consisting of three new species: P. novae-zelandiae sp. nov., P. franiae sp. nov. and P. adamsiae sp. nov. Phycodrys novae-zelandiae is the largest of the three, up to 20 cm in height, with a distinct midrib and multicellular, opposite to subopposite lateral macroscopic veins. It has entirely monostromatic blades except near the midrib and veins, and its procarp contains a three-celled sterile group one (st1) and a one-celled sterile group two (st2). Phycodrys franiae was previously treated as a cryptic species among herbarium collections of P. ‘quercifolia’. It is smaller (4–11 cm high) with weakly developed midribs and veins, the blade is tristromatic throughout, except at the growing margins, and the procarp consists of a four-celled st1 and a two–three-celled st2. Phycodrys adamsiae, previously reported as P. profunda, is a small decumbent or prostrate plant, 1–8 cm long, with a midrib and inconspicuous lateral veins. The blades are tristromatic with serrated margins, two–four-celled surface spines and multicellular marginal holdfasts that differ from those of Californian specimens. The tetrasporangia are borne on marginal bladelets. Phylogenetic analyses place the New Zealand species in a separate group that is distantly removed from most other Phycodrys species.     

Characterization of P1argF derivatives from Escherichia coli K12 transduction. I. IS1 elements flank the argF gene segment

Summary Specialized transducing derivatives of the temperate bacteriophage P1 (P1std) are selected by transduction into recipients with deletions in the corresponding genes (Stodolsky 1973). When Escherichia coli K12 strains are used as donors in such transduction experiments, P1argF derivatives can be selected. The argF gene is unique to these strains (Glansdorff et al. 1967). Under these experimental conditions P1argF are formed with frequencies 10,000 times greater than other P1std. The majority of the P1argF derivatives that have been analyzed are indistinguishable by cleavage analyses. One such derivative, P1argF5 has been characterized in detail. Heteroduplex analysis against P1, P7, and P1CmO identified an 11 kb insertion of DNA precisely at the naturally occurring IS1 locus of P1. Cleavage analysis with EcoRI, BamHI and PstI confirmed this finding. To further define the argF insertion, a P1Cm13argF derivative was constructed having the IS1 sequences of Cm13 and argF in opposite orientation. Intrastrand annealing of P1Cm13argF5 DNA established that the argF segment is flanked by directly repeated IS1 sequences. The IS1-argF-IS1 segment is desigmated Tn2901. The assignment of the map position of the argF gene within the 11 kb insert of P1argF5 is discussed. The evolutionary significance of this finding and a model for P1argF formation is also presented.     

Observations on gymnoascaceae. IX. A new species of pseudoarachniotus from soil-burial beds

Summary A new species ofPseudoarachniotus P. marginosporus, is described and illustrated. The developmental morphology of this new ascomycete is discussed. On a standard medium such as YpSs,P. marginosporus can be distinguished from other species of the genus by colonial coloration which varies from ochre-rust to very pale yellow at different stages of maturation. The colony ofP. roseus is red, red-orange or orange-yellow;P. citrinus is lemon yellow to brownish yellow in age;P. reticulatus is red orange andP. hyalinosporus is yellowish and usually with a great deal of green pigmentation in the mycelium and in the medium. Furthermore ascospores ofP. marginosporus are oblate, small and thin-walled, measuring 2.2–3.0×4.0–4.4 µ, with a minute elevated rim around the long axis, while ascospores ofP. reticulatus are globose and reticulate, and those ofP. roseus andP. citrinus are large and thick-walled, measuring about 4.4×7.7 µ. Ascospores ofP. hyalinosporus are similar in size and shape to those ofP. marginosporus, but lack a rim or other markings.     

Chloroplast DNA variation in Populus. II. Interspecific restriction fragment polymorphisms and genetic relationships among Populus deltoides,P. nigra,P. maximowiczii,and P. x canadensis

Restriction fragment analysis was conducted to determine interspecific chloroplast DNA (cpDNA) variation and genetic relationships among Populus deltoides, P. nigra, P. x canadensis (P. deltoides x P. nigra), and P. maximowiczii. Total cellular DNAs of these poplars were digested with 16 restriction endonucleases, and Southern blots of the restriction digests were probed with six different cloned cpDNA fragments from Petunia. P. deltoides, P. nigra, and P. maximowiczii each had a distinct chloroplast genome, separated by many restriction-site and restriction-fragment-length mutations, predominantly in the large single-copy region of the genome. P. x canadensis shared the same cpDNA restriction fragment patterns as P. deltoides var. deltoides. P. nigra was most diverged from P. deltoides, and P. deltoides showed close cpDNA relationships to P. maximowiczii. Nucleotide substitutions per site in cpDNA were 0.0036 between P. deltoides and P. maximowiczii, 0.0071 between P. nigra and P. maximowiczii, and 0.0077 between P. deltoides and P. nigra. We suggest that P. nigra should be classified in a new separate section, the Nigrae.     

Reproductive Biology of two Species of Phrynichus, P. exophthalmus Whittick, 1940 and P. deflersi arabicus nov. ssp. (Chelicerata: Amblypygi)

Courtship, mating and spermatophores of Phrynichus exophthalmus and P. deflersi arabicus nov. ssp. are described. Courtship of P. exophthalmus is more complex than in other amblypygids, with close contact between mates nearly throughout the mating dance. After spermatophore formation, the female is lured to the spermatophore and then firmly pressed onto it. Mating behaviour and spermatophore confirm the placement of this species in the Phrynichus ceylonicus group and show that the similarities with Euphrynichus, like long and thin pedipalps with bacilliform apophyses instead of spines, are the result of convergent evolution. Courtship of P. d. arabicus is conservative, similar to that of P. dhofarensis and many other amblypygids. After spermatophore formation, the female is lured to the spermatophore, then pulled over and pressed onto it. The results suggest that the P. ceylonicus group and the P. deflersi group and sister groups, but the low number of investigated species precludes a definite conclusion.     

Pleurosigma hinzianum sp. nov. and P. frenguellianum sp. nov. (Pleurosigmataceae,Bacillariophyta) from Argentinean coastal waters,in comparison with P. amara Stidolph and P. elongatum W. Smith

Two new marine diatom species from Argentinean coastal waters, Pleurosigma hinzianum Sterrenburg, Sunesen & Sar, sp. nov. and P. frenguellianum Sunesen, Sterrenburg & Sar, sp. nov., are described. The characters permitting their identification are specified, based on comparison with type material of the morphologically similar species P. amara Stidolph and P. elongatum W. Smith in the light (LM) and scanning electron microscope (SEM). New information on the type material of P. elongatum is presented and its taxonomic concept is emended. The main criteria for separation of the species discussed here are: valve outline, path of the raphe-sternum, raphe angle and angle of intersection of the oblique striae in LM; and external central and terminal raphe fissures, internal details of the central area, external and internal apical structure, and morphology of the hymen-occluded internal pores in SEM. The occurrence of these (and probably other) species in the genus Pleurosigma in net samples is adventitious and not indicative of a true planktonic mode of life.     

Variation in Potentilla sect. Aureae (Rosaceae) in the Baltic states

The morphological variation of four Baltic representatives of the genus Potentilla section Aurea–P. neumanniana, P. arenaria, P. subarenaria and P. crantzii was studied with multivariate methods. Altogether 41 characters were used. The most important characters for the phenetical classification are those of the epidermis: characters of stellate and glandular hairs and numbers of cells. Macromorphological characters are less important, the most useful of these being the length of sepals and stipules and the number of teeth of the central leaflet. All four species are significantly distinct. Even P. subarenaria, a putative hybrid of P. arenaria and P. neumanniana, is clearly separated. At the same time, the species are morphologically quite variable, and it is possible to distinguish subclusters (morphotypes) within P. neumanniana, P. subarenaria and P. crantzii, which are also statistically distinct. The varieties described by Wolf (1908) under the name P. verna (P. neumanniana) do not agree well with the morphs in our material. However, it can be admitted that var. typica and var. neumanniana axe prevalent, var. pseudo-incis? and var. incis? occur occasionally; only var. longifoli? can be quite clearly delimited.     

Evaluation of the ability of C. albicans to form biofilm in the presence of phage-resistant phenotypes of P. aeruginosa

Pseudomonas aeruginosa and Candida albicans are disparate microbial species, but both are known to be opportunistic pathogens frequently associated with nosocomial infections. The aim of this study was to provide a better understanding of the interactions between these microorganisms in dual-species biofilms. Several bacteriophage-resistant P. aeruginosa phenotypes have been isolated and were used in dual-species mixed-biofilm studies. Twenty-four and 48 h mixed-biofilms were formed using the isolated phenotypes of phage-resistant P. aeruginosa and these were compared with similar experiments using other P. aeruginosa strains with a defined lipopolysaccharide (LPS) deficiency based on chromosomal knockout of specific LPS biosynthetic genes. Overall, the results showed that the variants of phage-resistant P. aeruginosa and LPS mutants were both less effective in inhibiting the growth of C. albicans in mixed-biofilms compared to the wild-type strains of P. aeruginosa. Conversely, the proliferation of P. aeruginosa was not influenced by the presence of C. albicans. In conclusion, the ability of strains of P. aeruginosa to inhibit the formation of a biofilm of C. albicans appears to be correlated with the LPS chain lengths of phenotypes of P. aeruginosa, suggesting that LPS has a suppressive effect on the growth of C. albicans.     

Pohlia muyldermansii Wilcz. & Dem. var. pseudomuyldermansii var. nov., a new name for P. muyldermansii Wilcz. & Dem. sensu Lewis & Smith

Abstract

The results of a comparative study of Pohlia muyldermansii from Continental Europe and the British Isles are presented. Two varieties are recognized, var. muyldermansii from Belgium and the Netherlands and var. pseudomuyldermansii var. nov. from Great Britain, Ireland, Austria and Switzerland. P. camptotrachela is reported from Belgium and differences between this species and P. muyldermansii discussed.     

A Comparative Study of the Infraciliature and Silverline System of the Fresh-Water Scuticociliates Pseudocohnilembus putrinus (Kahl, 1928) nov. comb., P. pusillus (Quennerstedt, 1869) nov. comb., and the Marine Form P. marinus Thompson, 19661

Three species of Pseudocohnilembus were examined with respect to infraciliature and the silverline system. The freshwater species P. putrinus and P. pusillus exhibited no differences in general organization of the argyrophilic structures when compared with the marine P. marinus. A review of the Pseudocohnilembus species that have been described on the basis of silver preparations shows that at present four species have been well characterized: P. pusillus (Quennerstedt, 1869) nov. comb., P. putrinus (Kahl, 1928) nov. comb., P. hargisi Evans & Thompson, 1964, and P. marinus Thompson, 1966, P. persalinus Evans & Thompson, 1964 and P. longiseta Evans & Thompson, 1964 are regarded as identical with the older known P. pusillus, because with respect to morphology and argyrophilic structures they are within the range of variability of that species; and their names thus fall as synonyms of P. pusillus.     

On the identity of Pohlia flexuosa Harv. with P. muyldermansii Wilcz. & Dem.

Abstract

The identity of Pohlia flexuosa Harv. with P. muyldermansii Wilcz. & Dem. is established. Recent gatherings from several Asiatic countries demonstrate that material of P. flexuosa occurs with propagula identical with those of P. muyldermansii var. muyldermansii, of var. pseudomuyldermansii Arts, Nordhorn-Richter and Smith and with a mixture of both and intermediate types of propagulum; var. pseudomuyldermansii cannot therefore be upheld as distinct. It is postulated that P. flexuosa has been introduced into Europe in two distinctive clones.     

Pollen competition among Populus deltoides Marsh., P. nigra L. and P. maximowiczii Henry in fertilizing P. deltoides ovules and siring its seed crop

Summary Interspecific pollen competition among Populus deltoides, P. nigra and P. maximowiczii in fertilizing P. deltoides ovules was studied by using a pollen mixture technique, allozymes and leaf morphology. The frequencies of F₁ seedlings of different paternities in pollen-mix crosses showed highly significant (P<0.01) departures from the 11 ratio expected if pollen selection was random. P. deltoides pollen was the most competitive. The mean percentages of F₁ seedlings of P. deltoides paternity in crosses with pollen mixes P. deltodes + P. nigra, P. deltoides + P. maximowiczii, and P. deltoides + P. nigra + P. maximowiczii were 95.0, 92.5, and 84.8, respectively. P. maximowiczii pollen was more competitive than P. nigra pollen, which was at a selective disadvantage. An average of 83.6% of F₁ progenies of the eight crosses with P. nigra + P. maximowiczii pollen showed P. maximowiczii paternity. Also, in four crosses with P. deltoides + P. nigra + P. maximowiczii pollen, the relative proportion of P. deltoides × P. maximowiczii seedlings (13.4%) was higher than that of P. deltoides × P. nigra seedlings (1.8%). Pollen proportions in the pollen mixes and pollen size did not significantly affect the competitive ability of the pollen. The relative pollen competitive ability indicated reproductive affinities among the species.     

Use of chloroplast DNA polymorphisms for the phylogenetic study of seven Phaseolus taxa including P. vulgaris and P. coccineus

The genetic variability of seven Phaseolus taxa has been evaluated on the basis of molecular data and the results have used to clarify the phyletic relationships between several taxa of the P. coccineus L. complex. Chloroplast DNA (cpDNA) from 33 populations was digested with six restriction endonucleases, revealing some polymorphisms that made it possible to divide most of the taxa into two main groups: the subspecies of P. coccineus on the one hand, and P. vulgaris L., P. polyanthus Greenman and P. costaricensis (Freytag and Debouck) on the other hand. P. polyanthus is closer to P. vulgaris than the other taxa of the second group and should be considered as a separate species. The position of the wild species P. costaricensis is intermediate between P. coccineus and P. polyanthus. P. glabellus shows sufficient polymorphisms at the cpDNA level to be recognized as a separate species, as previously suggested from total seed-protein electrophoretic studies. These results favour the hypothesis of a common phylogeny for P. vulgaris, P. polyanthus, P. costaricensis and P. coccineus from a single wild ancestor. Although cpDNA is generally known to be uniform at the intraspecific level, some additional polymorphisms were also detected within P. vulgaris, P. polyanthus and P. coccineus. Further studies are required to understand the significance of the latter.