Cotton is a potential and excellent candidate to balance both agricultural production and remediation of mercury-contained soil, as its main production fiber hardly involves into food chains. However, in cotton, there is known rarely about the tolerance and response to mercury (Hg) environments. In this study, the biochemical and physiological damages, in response to Hg concentrations (0, 1, 10, 50 and 100 µM), were investigated in upland cotton seedlings. The results on germination of cottonseeds indicated the germination rates were suppressed by high Hg levels, as the decrease of percentage was more than 10% at 1000 µM Hg. Shoots and roots’ growth were significantly inhibited over 10 µM Hg. The inhibitor rates (IR) in fresh weight were close in values between shoots and roots, whereas those in dry weight the root growth were more obviously influenced by Hg. In comparison of organs, the growth inhibition ranked as root > leaf > stem. The declining of translocation factor (TF) opposed the Hg level as even low to 0.05 at 50 µM Hg. The assimilation in terms of photosynthesis, of cotton plants, was affected negatively by Hg, as evidenced from the performances on pigments (chlorophyll a and b) and gas exchange (Intercellular CO2 concentration (Ci), CO2 assimilation rate (Pn) and stomatal conductance (Gs)). Sick phenotypes on leaf surface included small white zone, shrinking and necrosis. Membrane lipid peroxidation and leakage were Hg dose-dependent as indicated by malondialdehyde (MDA) content and relative conductivity (RC) values in leaves and roots. More than 10 µM Hg damaged antioxidant enzyme system in both leaves and roots (p < 0.05). Concludingly, 10 µM Hg post negative consequences to upland cotton plants in growth, physiology and biochemistry, whereas high phytotoxicity and damage appeared at more than 50 µM Hg concentration.

Tobacco is a model plant for studying flower coloration. Flavonoids and carotenoids were reported to contribute to the flower color in many plants. We investigated the mechanism underlying flower color formation in tobacco by comparing the profiling flavonoids and carotenoids between various species Nicotiana tabacum L. and Nicotiana rustica L., as their flowers commonly presented red (pink) and yellow (orange), respectively. The metabolomes were conducted by UPLC–ESI–MS/MS system. The main findings were as follows: (1) A total of 31 flavonoids and 36 carotenoids were identified in all four cultivars involved in N. tabacum and N. rustica. (2) Flavonoids and carotenoids tended to concentrate in the red flowers (N. tabacum) and yellow flowers (N. rustica), respectively. (3) About eight flavonoids and 12 carotenoids were primarily screened out for metabolic biomarkers, such as the robust biomarker involving kaempferol-3-o-rut, quercetin-glu, rutin, lutein, and β-carotene. This is the first research of systematic metabolome involving both flavonoids and carotenoids in tobacco flower coloration. The metabolic mechanism concluded that flavonoids and carotenoids mainly contributed to red (pink) and yellow (orange) colors of the tobacco flowers, respectively. Our finding will provide essential insights into characterizing species and modifying flower color in tobacco breeding through genetic improvement or regulation of featured metabolic synthesis.

Gynura cusimbua (D. Don) S. Moore is a favorite food vegetable and traditional folk medicine. The chloroplast genome information, of G. cusimbua , was introduced and released in this study. The complete chloroplast genome was characterized as 156, 684 base pairs (bp) in length. The circle gDNA contained four segments, namely LSC (large single copy), SSC (small single copy) and two IRs (inverted repeats), which was 86, 834 bp and 18, 414 bp and 25, 718 bp in length separately. The total GC content was 36.88%. A total of 125 genes were characterized in the chloroplast genome, where 84, 33 and 8 genes were for coding-proteins, tRNA and rRNA respectively. The phylogeny tree demonstrated that G. cusimbua was clustered with Jacobaea valgaris and Senecio valgaris . This study would fill a vacancy of chloroplast genome information involving G. cusimbua , and provide new genetic resources for the study on Senecioninae .

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Cotton is a potential and excellent candidate to balance both agricultural production and reme-diation of mercury-contained soil, as its main production fiber hardly involve into food chains. However, there is known rarely about the tolerance and response to Hg environments in cotton. In this study, The biochemical and physiological damages, in response to mercury (Hg), were investigated in upland cotton seedlings. The results on cottonseeds germination, indicated the germination rate were suppressed by high Hg levels, as the decrease of percentage was more than 10% at 1000 &micro;M Hg. Shoots and roots&rsquo; growth were significantly inhibited above 10 &micro;M Hg. The inhibitor rates (IR) in fresh weight were close between shoots and roots, whereas that in dry weight the root growth was more obviously influenced by Hg. In comparison of organs, the growth inhibition ranked as root &gt; leaf &gt; stem. The declining of translocation factor (TF) op-posed the Hg level even as low to 0.05 at 50 &micro;M Hg. The assimilation of cotton plants was af-fected negatively by Hg toxicity, as evidenced from the performances on photosynthesis pig-ments (chlorophyll a and b) and gas exchange (Intercellular CO2 concentration (Ci), CO2 assimila-tion rate (Pn) and stomatal conductance (Gs)). Sick phenotypes on leaf surface included small white zone, shrinking and necrosis. Membrane lipid peroxidation and leakage were Hg dose-dependent as indicated by malondialdehyde (MDA) content and relative conductivity (RC) values in leaves and roots. More than 10 &micro;M Hg damaged antioxidant enzyme system in both leaves and roots (P&lt;0.05). Concludingly, 10 &micro;M Hg post negative consequences to upland cotton plants in growth, physiology and biochemistry, whereas high phytotoxicity and damage ap-peared at more than 50 &micro;M Hg concentration.