BackgroundVery little information is available about soil algae in Taiwan. In this study, we investigated for the first time the soil algae inhabiting five types of farmland in mid-Taiwan: rice paddies, vegetable farms, tea plantations, sugar cane farms, and orchards.ResultsSixty-four taxa belonging to 33 genera of cyanobacteria, diatoms, green algae, and euglenoids were identified on the basis of fine structures observed under optical and electron microscopes and rDNA sequencing. The majority of the isolates were of the genera Oscillatoria, Navicula, Nitzschia, and Pinnularia. Five species were reported for the first time in Taiwan, namely Microcoleus paludosus, M. subtorulosus, Navicula subminuscula, Nitzschia levidensis, and Ni. pusilla.ConclusionsThe distribution and diversity of these species was shown to be strongly dependent on habitat, with the highest diversity of green algae in the orchards, a fairly high diversity of diatoms and cyanobacteria in the rice paddies, and a relatively low diversity in the tea plantations and sugar cane farms. The humidity and acidity were the most important environmental factors influencing the diversity of soil algae in these farmlands.Electronic supplementary materialThe online version of this article (doi:10.1186/1999-3110-54-41) contains supplementary material, which is available to authorized users.

Tolerance to drought stress in soil crust microorganisms is essential for exploiting suitable organisms for restoring soil. In this study, the responses to drought stress of two drought-tolerant species, a green alga and a cyanobacterium, were compared with those of two non-tolerant green algae. In response to drought stress, induced by treatment with polyethylene glycol, the intracellular proline levels increased and were associated with increases in malondialdehye, pigment contents, and enzyme activities such as superoxide dismutase (SOD) and peroxidase (POD). Our results suggest that tolerance to drought stress could be indicated by the intracellular levels of proline, SOD, and carotenoids. This study provides insights into the drought physiology of the photosynthetic microorganisms and suggests that Leptolyngbya boryana and Chlorella vulgaris are suitable pioneer organisms for soil restoration.

No abstract

BackgroundIn the marine brown macroalgae, the morphological characters are highly similar between two widely distributed genera, Homoeostrichus and Zonaria (Dictyotaceae), thereby resulting in the difficulty of exploring their hidden biodiversity. Owing to the help of the molecular tools, it is now easy for scientists to objectively describe a new species in nature. In this study, we make a description on the Homoeostrichus formosana sp. nov. from Taiwan, Indo-Pacific Ocean based on the morphological evidence and molecular data.ResultsOur morphological observations revealed that this species has marginal row of apical cells responsible for thallus growth and the thallus with four layers of cells except the marginal regions. The cortical cell lies upon each medullary cell in transverse section, and two cortical cells upon each medullary cell in longitudinal section. Tetrasporangium is developed from cortical cell with stalk cell and singly scattered over the thallus surface, and has no indusia and paraphyses. Molecularly, the phylogenetic trees based on SSU, psaA, psbA, and rbcL gene sequences supported that Homoeostrichus species are closely related to Exallosorus species and clearly separated from each others in addition to Zonaria species.ConclusionsHomoeostrichus formosana sp. nov. can now be clearly distinguished from E. harveyanus and Japanese H. flabellatus.Electronic supplementary materialThe online version of this article (doi:10.1186/1999-3110-54-13) contains supplementary material, which is available to authorized users.