Transcriptome Profiling and Chlorophyll Metabolic Pathway Analysis Reveal the Response of Nitraria tangutorum to Increased Nitrogen.

To identify genes that respond to increased nitrogen and assess the involvement of the chlorophyll metabolic pathway and associated regulatory mechanisms in these responses, Nitraria tangutorum seedlings were subjected to four nitrogen concentrations (N0, N6, N36, and N60: 0, 6, 36, and 60 mmol·L-1 nitrogen, respectively). The N. tangutorum seedling leaf transcriptome was analyzed by high-throughput sequencing (Illumina HiSeq 4000), and 332,420 transcripts and 276,423 unigenes were identified. The numbers of differentially expressed genes (DEGs) were 4052 in N0 vs. N6, 6181 in N0 vs. N36, and 3937 in N0 vs. N60. Comparing N0 and N6, N0 and N36, and N0 and N60, we found 1101, 2222, and 1234 annotated DEGs in 113, 121, and 114 metabolic pathways, respectively, classified in the Kyoto Encyclopedia of Genes and Genomes database. Metabolic pathways with considerable accumulation were involved mainly in anthocyanin biosynthesis, carotenoid biosynthesis, porphyrin and chlorophyll metabolism, flavonoid biosynthesis, and amino acid metabolism. N36 increased δ-amino levulinic acid synthesis and upregulated expression of the magnesium chelatase H subunit, which promoted chlorophyll a synthesis. Hence, N36 stimulated chlorophyll synthesis rather than heme synthesis. These findings enrich our understanding of the N. tangutorum transcriptome and help us to research desert xerophytes' responses to increased nitrogen in the future.

Divergent leaf and fine root "pressure-volume relationships" across habitats with varying water availability.

Fine roots and leaves, the direct interfaces of plants with their external environment along the soil-plant-atmosphere continuum, are at the front line to ensure plant adaptation to their growing habitat. This study aimed to compare the vulnerability to water deficit of fine roots and leaves of woody species from karst and mangrove forests-two water-stressed habitats-against that of timber and ornamental woody species grown in a well-watered common garden. Thus, pressure-volume curves in both organs of 37 species (about 12 species from each habitat) were constructed. Fine roots wilted at a less negative water potential than leaves in 32 species and before branch xylem lost 50% of its hydraulic conductivity in the 17 species with available data on branch xylem embolism resistance. Thus, turgor loss in fine roots can act as a hydraulic fuse mechanism against water stress. Mangroves had higher leaf resistance against wilting and lower leaf-specific area than the karst and common garden plants. Their fine roots had high specific root lengths (SRL) and high capacitance to buffer water stress. Karst species had high leaf bulk modulus, low leaf capacitance, and delayed fine root wilting. This study showed the general contribution of fine roots to the protection of the whole plant against underground water stress. Our findings highlight the importance of water storage in the leaves and fine roots of mangrove species and high tolerance to water deficit in the leaves of mangrove species and the fine roots of some karst species.

Antidiabetic effect of Pycnogenol French maritime pine bark extract in patients with diabetes type II.

A double-blind, placebo-controlled, randomized, multi-center study was performed with 77 diabetes type II patients to investigate anti-diabetic effects of the French maritime pine bark extract, Pynogenol. Supplementation with 100 mg Pycnogenol for 12 weeks, during which a standard anti-diabetic treatment was continued, significantly lowered plasma glucose levels as compared to placebo. HbA1(c) was also lowered; however, the difference as compared to placebo was statistically significant only for the first month. In the Pycnogenol-group endothelin-1 was significantly decreased, while 6-ketoprostaglandin F(1a) in plasma was elevated compared to placebo. Nitric oxide levels in plasma increased during treatment in both groups, but, differences did not reach statistical significance. Pycnogenol was well-tolerated with ECG, electrolytes, creatinine and blood urea nitrogen remaining unchanged in both groups. Mild and transient unwanted effects were reported for both groups without significant differences. Supplementation of Pycnogenol to conventional diabetes treatment lowers glucose levels and improves endothelial function.

Pycnogenol, French maritime pine bark extract, improves endothelial function of hypertensive patients.

A placebo-controlled, double-blind, parallel group study was performed with 58 patients to investigate effects of French maritime pine bark extract, Pycnogenol, on patients with hypertension. Supplementation of the patients with 100 mg Pycnogenol over a period of 12 weeks helped to reduce the dose of the calcium antagonist nifedipine in a statistically significant manner. The intake of Pycnogenol decreased endothelin-1 concentrations significantly compared to placebo while concentrations of 6-keto prostaglandin F1a in plasma were significantly higher compared to placebo. Values for nitric oxide (NO) in plasma increased in both groups, but the differences were not significant. Angiotensin II concentrations in plasma were lowered in the placebo group to a larger extent than in the Pycnogenol group. Heart rate, electrolytes and blood urea nitrogen were not changed during treatment in both groups of patients. Unwanted effects observed in both groups were of mild and transient nature, such as gastrointestinal problems, vertigo, headache and nausea. Differences in rate of side effects were not statistically significant between the two groups. Study results support a supplementation with Pycnogenol for mildly hypertensive patients.