ABSTRACT Witkowski, A.; Li, C. L.; Zg[lstrok]obicka, I.; Yu, S. X.; Ashworth, M.; Dąbek, P.; Qin, S.; Tang, C.; Krzywda, M.; Ruppel, M.; Theriot, E. C.; Jansen, R. K.; Car, A.; Płociński, T.; Wang, Y. C.; Sabir, J. S. M.; Daniszewska-Kowalczyk, G.; Kierzek, A., and Hajrah, N. H., 2016. Multigene assessment of biodiversity of diatom (Bacillariophyceae) assemblages from the littoral zone of the Bohai and Yellow Seas in Yantai region of Northeast China with some remarks on ubiquitous taxa. Diatoms are important contributors to the benthic microeukaryote flora. This manuscript lays the foundation for future metagenomic and environmental sequencing projects off coastal China by curating diatom DNA sequences from the Yantai region of the Bohai and Yellow Seas (Northeast China). These studies are based on cultures established from samples collected in different seasons from marine littoral and supralittoral zones in 2013 and 2014. Thirty-six diatom strains were cultured successfully and identification of these clones was determined by light and scanning electron microscopy(LM and SEM) and DNA sequencing of the nuclear-encoded small subunit ribosomal RNA (SSU)and chloroplast-encoded rbcL and psbC genes. The strains primarily represent raphid pennate genera, such as Amphora, Amphora (Oxyamphora), Caloneis, Diploneis, Halamphora, Navicula, Nitzschia, Parlibellus, Pleurosigma, Surirella and Tryblionella. When the DNA markers from these strains were analysed in a multi-gene phylogeny, we found that some clones-particularly within the genera Amphora, Navicula and Nitzschia—show greater than expected genetic diversity despite their very similar morphology and morphometrics. We also compared the molecular and morphological identities of several seemingly ubiquitous marine littoral taxa in the genera Amphora and Nitzschia from the Indian Ocean and Atlantic Ocean, the Red Sea and Adriatic Sea to their Yellow Sea counterparts.

The identity of a small-celled diatom Naviculadicta pseudofallacia WITKOWSKI, METZELTIN et LANGE-BERTALOT, originally described from Bear Island, southernmost island of the Norwegian archipelago Svalbard, is reconsidered. Observations of marine samples from the Kerguelen archipelago (Southern Ocean, Indian Ocean sector) revealed that this species also occurs in the Subantarctic region. The original classification within Naviculadicta was erroneous since this species is a monoraphid taxon and belongs to the Achnanthales. Its morphological features justify creating a new genus Scalariella RIAUX-GOBIN, which is distinguished from other achnanthoid genera by a peculiar raphe system, the stria structure of the sternum valve (each stria composed of a depressed macroareola), and the presence of a lateral solid area in the raphe valve, splitting each stria into two areolae. Based on light and electron microscopy, N. pseudofallacia is renamed Scalariella pseudofallacia (WITKOWSKI, METZELTIN et LANGE-BERTALOT) RIAUX-GOBIN et WITKOWSKI comb. nov. The genus also includes a second and rare species, observed in the Kerguelen material, S. oblongella RIAUX-GOBIN, WITKOWSKI et RUPPEL, which is described and illustrated, but which needs complementary observations. The morphology of Scalariella is compared to that of some genera split from the genus Achnanthes BORY. The biogeography of Scalariella pseudofallacia, a marine taxon probably misidentified in the past due to its small size, is reconsidered with respect to its affinity for subpolar, cold water habitats, in both hemispheres.

A new species of Cocconeis has been found growing on thalli of the invasive green alga Caulerpa taxifolia collected from the Croatian Adriatic Sea (Bay of Stari Grad, the Island of Hvar, Central Adriatic, Croatia), the coasts of the Mediterranean (Saint Raphaël, west of Cannes, France) and the eastern coast of Australia (Moreton Bay, southeast Queensland). Additionally, it was observed on samples of Caulerpa racemosa, another invasive alga in the Mediterranean. Preserved thalli of Caulerpa and cleaned material of the new diatom were studied by light and electron microscopy (SEM and TEM). The morphology and fine structure of the new marine epiphytic diatom, for which we propose the name Cocconeis caulerpacola Witkowski, Car & Dobosz, was determined, including the internal and external structure of the raphe and sternum valve, and the cingulum. Comparison between the new species and three closely related species, C. borbonica, C. diruptoides and C. pseudodiruptoides, was made using material from our samples, as well as material from Vis (Adriatic Sea) obtained from the Hustedt collection. Surprisingly, C. caulerpacola is able to colonize Caulerpa taxifolia in very high abundance, but its occurrence seems to be strongly patchy. Indeed, it seems that C. taxifolia is a suitable host for epiphytic diatoms, in particular this tiny Cocconeis, despite its reputation as a ‘killer seaweed’. Cocconeis caulerpacola was observed on Caulerpa species in varying abundance over a wide geographical range.

This study describes the diatom species Planothidium iberense sp. nov. from a salinity gradient of the Ebro River Estuary in northeastern Spain. A detailed description is given based on light and scanning electron microscopy observations, and the diatom species is compared with morphologically similar Planothidium species. Planothidium iberense is distinguished from P. linkei mainly by its morphometric characteristics, but also by the presence of multiseriate striae, in contrast to biseriate striae in P linkei. Planothidium iberense is also distinguished from P delicatulum and P. septentrionale by the presence of an one-side expanded central area on the sternum valve, which is absent in the latter two Planothidium species.

This is our second paper focusing on new diatom taxa of the San Francisco Bay area. Previously we described 11 spe- cies of Navicula s.str. as new for science. Here we present another new naviculoid species of the genus Fogedia. This new species bears the distinguishing features of the genus, including a straight internal raphe slit and short, simple external distal raphe ends. The species differs from similar Fogedia taxa by being smaller and having coarser stria and lower lineola density. With this new species of Fogedia, the number of diatoms new for science from San Francisco Bay and vicinity is 12, with more awaiting description. We discuss the relationships between the newly described and established species of Fogedia, and present their patterns of biogeographic distribution.

In the course of research on the diatoms from surface sediments sampled in the marine littoral and sublittoral worldwide, and in some freshwater localities in central Europe, several problematic taxa were encountered resembling Nitzschia parvula. We therefore undertook a light and scanning electron microscopical study of five species of Nitzschia belonging to the section Tryblionella. After a period of misidentification, one of the taxa studied, N. parvula, is now known front the type preparation. The remaining taxa are either new to science or have previously lacked formal descriptions. The first of them is found in freshwater habitats and is described here as N. beyeri Lange-Bertalot, whereas the second, from the tropical marine littoral, is described as N. schweikertii Witkowski, Lange-Bertalot, Ruppel & Kociolek. The third species is known in the literature by the manuscript name 'Nitzschia subconstricta Grunow'. However, this name was not validly published and subconstricta has recently been used for another species, described by Desikachary & Prema (1987). Grunow's species is validly described here as N. ligowskii Witkowski, Lange-Bertalot, Kociolek & Brzezinska. It inhabits the marine littoral and is characterized by a very wide geographical distribution. The fourth new taxon, described here as N. buschbeckii Witkowski, Lange-Bertalot & Ruppel is known so far only from the Antarctic.

The host range of the soilborne obligate biotroph, Plasmodiophora brassicae was investigated. Evidence is presented that infection by P. brassicae might occur in non-Brassica species, leading to the potential formation of resting spores. Structures resembling P. brassicae were found in the root cortex of Tropaeolum majus, Carica papaya, Reseda alba and Beta vulgaris as demonstrated by scanning electron microscopy. Inoculation of Brassica rapa roots with spores extracted from either T. majus or B. vulgaris roots which had been previously inoculated with P. brassicae led to development of clubroot in the roots of B, rapa. It was also shown that the development of the symptom might be: correlated with glucosinolate content, although other host factors are implicated in the B. vulgaris interaction with P. brassicae. In the glucosinolate-containing non-Brassicas, T. majus and C. papaya, the concentrations of benzylglucosinolate increased markedly in roots inoculated with P. brassicae, compared with the controls. There were also increases in concentrations of benzylglucosinolate in leaves of T. majus after P. brassicae infection. However, in R. alba roots, the total glucosinolate content decreased after inoculation with P. brassicae compared with the controls. High root concentrations of 2-OH-2-phenylethylglucosinolate (glucobarbarin) compared with low root indole glucosinolates in this species might limit P. brassicae infection and development. The importance of our investigations in relation to cultivation of non-Brassica species on fields infested with P. brassicae is discussed.

Mutants and wild type plants of Arabidopsis thaliana were analysed for differences in glucosinolate accumulation patterns, indole-3-acetic acid (IAA) biosynthesis and phenotype. A previously identified series of mutants, termed TU, with altered glucosinolate patterns was used in this study. Only the line TU8 was affected in shoot phenotype (shorter stems, altered branching pattern). Synthesis of IAA and metabolism were not much affected in the TU8 mutant during seedling development, although the content of free IAA peaked earlier in TU8 during plant development than in the wild type. Indole glucosinolates and IAA may, however, be involved in the development of clubroot disease caused by the obligate biotrophic fungus Plasmodiophora brassicae since the TU3 line had a lower infection rate than the wild type, and lines TU3 and TU8 showed decreased symptom development. The decline in clubroot formation was accompanied by a reduced number of fungal structures within the root cortex and slower development of the fungus. Indole glucosinolates were lower in infected roots of TU3 and TU8 than in control roots of these lines, whereas in wild-type plants the differences were not as prominent. Free IAA and indole-3-acetonitrile (IAN) were increased in infected roots of the wild type and mutants with normal clubroot symptoms, whereas they were reduced in infected roots of mutants TU3 and TU8. These results indicate a role for indole glucosinolates and IAN/IAA in relation to symptom development in clubroot disease.

A convenient method for infecting Brassica seedlings in liquid medium with the Phytopathogenic fungus Plasmodiophora brassicae was developed. The infection rates of two susceptible and two tolerant Chinese cabbage varieties with wild type P. brassicae were investigated. The content of free indole-3-acetic acid (IAA) was determined using combined gas chromatography-mass spectrometry (GC-MS) with [13 C6 ]-IAA as internal standard during the first period of infection with the fungus (5-14 d) and compared with the indole glucosinolate content of two Chinese cabbage varieties (one tolerant, one susceptible) in the same developmental stages, The results showed that the mean of the IAA content in the infected plants was approximately 66.5% higher than that of the non-infected controls. In both the susceptible and tolerant varieties higher levels of IAA were found in the infected plants 10 d after the beginning of incubation. After 14 d of incubation IAA levels decreased in the susceptible, infected plants and increased in the tolerant, infected plants.