The halophyte Suaeda salsa displayed strong resistance to salinity. Up to date, molecular mechanisms underlying tolerance of S . salsa to salinity have not been well understood. In the present study, S . salsa seedlings were treated with 30‰ salinity and then leaves and roots were subjected to Illumina sequencing. Compared with the control, 68,599 and 77,250 unigenes were significantly differentially expressed in leaves and roots in saline treatment, respectively. KEGG enrichment analyses indicated that photosynthesis process, carbohydrate, lipid and amino acid metabolisms were all downregulated in saline treatment, which should inhibit growth of S . salsa . Expression levels of Na + /H + exchanger, V-H + ATPase, choline monooxygenase, potassium and chloride channels were upregulated in saline treatment, which could relieve reduce over-accumulation of Na + and Cl - . Fe-SOD, glutathione, L-ascorbate and flavonoids function as antioxidants in plants. Genes in relation to them were all upregulated, suggesting that S . salsa initiated various antioxidant mechanisms to tolerate high salinity. Besides, plant hormones, especially auxin, ethylene and jasmonic acid signaling transduction pathways were all upregulated in response to saline treatment, which were important to gene regulations of ion transportation and antioxidation. These changes might comprehensively contribute to tolerance of S . salsa to salinity. Overall, the present study provided new insights to understand the mechanisms underlying tolerance to salinity in halophytes.

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The purslane Portulaca oleracea L. is a promising crop species for agriculture in saline-alkali soils. Up to date, biochemical and molecular changes in purslane in response to salinity were seldom reported. To investigate biochemical effects of salinity on purslane, seedlings were treated with different concentrations of NaCl for up to 14 days. The results showed that treatments with 150 mM and 200 mM NaCl significantly decreased dry and fresh weight of seedlings, shoot and root length as well as leaflet number on main stem, demonstrating inhibition on purslane growth. Treatments with 100-200 mM NaCl significantly decreased net photosynthetic rate, increased intercellular CO 2 concentration, MDA content and production rate of O 2 − , induced activities of SOD, POD and CAT, suggesting inhibition on photosynthesis and induction of oxidant stress. With longer exposure time, activities of antioxidant enzymes showed decreasing tendency, probably due to denaturation of proteins and damages of cell membrane. In treatments with 150 mM and 200 mM NaCl, Na + content increased in purslane leaf, stem and root, which then decreased K + content, probably due to membrane depolarization and regulation of ion channels. Moreover, transcriptome profiles in leaves were compared among treatments with 200 mM for 0, 2, 6, 12 and 24 h. The results suggested that saline treatments down-regulated transcription levels of genes involved in photosynthesis, energy metabolism, lignin biosynthesis and signaling transduction. Overall, the present study uncovered biochemical and molecular responses of purslane to salinity, which should be useful for agriculture of purslane on saline-alkali soils.

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Chinese Douglas-fir (Pseudotsuga sinensis) is an endangered Pinaceae species found in several isolated regions of China. Although soil spore banks of ectomycorrhizal (ECM) fungi can play an important role in seedling establishment after disturbance, such as in the well-known North American relative (Pseudotsuga menziesii), we have no information about soil spore bank communities in relict forests of Chinese Douglas-fir. We conducted bioassays of 73 soil samples collected from three Chinese Douglas-fir forests, using North American Douglas-fir as bait seedlings, and identified 19 species of ECM fungi. The observed spore bank communities were significantly different from those found in ECM fungi on the roots of resident trees at the same sites (p = 0.02). The levels of potassium (K), nitrogen (N), organic matter, and the pH of soil were the dominant factors shaping spore bank community structure. A new Rhizopogon species was the most dominant species in the spore banks. Specifically, at a site on Sanqing Mountain, 22 of the 57 surviving bioassay seedlings (representing 21 of the 23 soil samples) were colonized by this species. ECM fungal richness significantly affected the growth of bioassay seedlings (R = 0.20, p = 0.007). Growth was significantly improved in seedlings colonized by Rhizopogon or Meliniomyces species compared with uncolonized seedlings. Considering its specificity to Chinese Douglas-fir, predominance in the soil spore banks, and positive effect on host growth, this new Rhizopogon species could play critical roles in seedling establishment and forest regeneration of endangered Chinese Douglas-fir.