Amomum tsaoko DRM1 regulate seed germination and improve heat tolerance in Arabidopsis.

Seed dormancy and germination are critical to medicinal plant reproduction. Dormancy-associated gene (DRM1) has been involved in the regulation of dormancy in Arabidopsis meristematic tissues or organs. However, research on molecular functions and regulations of DRM1 in Amomum tsaoko, an important medicinal plant, is rare. In this study, the DRM1 was isolated from embryos of A. tsaoko, and the results of protein subcellular localization in Arabidopsis protoplast indicated that DRM1 was mainly nucleus and cytoplasm. Expression analysis showed that DRM1 especially exhibited the highest transcript level in dormant seed and short-time stratification while displaying a high response of hormone and abiotic stress. Further investigation showed that ectopic expression of DRM1 in Arabidopsis exhibited delayed seed germination and germination capability to high temperatures. Additionally, DRM1 transgenic Arabidopsis exhibited increased tolerance to heat stress by enhancing antioxidative capacities and regulating stress-associated genes (AtHsp25.3-P, AtHsp18.2-CI, AtHsp70B, AtHsp101, AtGolS1, AtMBF1c, AtHsfA2, AtHsfB1 and AtHsfB2). Overall, our results reveal the role of DRM1 in seed germination and abiotic stress response.

Comparison of metabolites and variety authentication of Amomum tsao-ko and Amomum paratsao-ko using GC-MS and NIR spectroscopy.

Amomum tsao-ko, as an edible and medicinal variety, has been cultivated for more than 600 years in China. Recently, two cultivars, A. tsao-ko and Amomum paratsao-ko, were found in A. tsao-ko planting area. The two cultivars are often confused because of the similar phenotype and difficult to distinguish through sensory judgment. In this study, the non-targeted gas chromatography-mass spectrometry (GC-MS) metabolomics combined with near-infrared spectroscopy (NIRS) were used for dissecting the two cultivars with phenotypic differences. According to principal component analysis (PCA) loading diagram and orthogonal partial least squares discriminant analysis (OPLS-DA) S-plot of the metabolites, the accumulation of major components including 1,8-cineole, α-phellandrene, (E)-2-decenal, (-)-ß-pinene, (E)-2-octenal, 1-octanal, D-limonene, and decanal, were present differences between the two cultivars. Seven metabolites potential differentiated biomarkers as ß-selinene, decamethylcyclopentasiloxane, (E,Z)-2,6-dodecadienal, (E)-2-hexenal, (E)-2-decenal, isogeranial, 1,8-cineole and ß-cubebene were determined. Although A. tsao-ko and A. paratsao-ko belong to the same genera and are similar in plant and fruit morphology, the composition and content of the main components were exposed significant discrepancy, so it is necessary to distinguish them. In this study, the discriminant model established by GC-MS or NIRS combined with multivariate analysis has achieved a good classification effect. NIRS has the advantages of simple, fast and nondestructive and can be used for rapid identification of varieties and fruit tissues.

2,8-Decadiene-1,10-Diol Inhibits Lipopolysaccharide-Induced Inflammatory Responses Through Inactivation of Mitogen-Activated Protein Kinase and Nuclear Factor-κB Signaling Pathway.

Amomum tsao-ko (A. tsao-ko) has been used as a traditional medicine for the treatment of infectious and digestive disorders. In the present study, we report the anti-inflammatory activity and molecular mechanism of 2,8-decadiene-1,10-diol (DDO) isolated from the extract of A. tsao-ko in lipopolysaccharide-stimulated RAW 264.7 cells. DDO treatment inhibited the production of nitric oxide and prostaglandin E2 by downregulating inducible nitric oxide synthase and cyclooxygenase-2 expression, respectively. Moreover, DDO suppressed the production of pro-inflammatory cytokines such as interleukin-6 and tumor necrosis factor-α. These inhibitory effects of DDO on the expression of inflammatory proteins were found to be mediated through the inactivation of mitogen-activated protein kinases (MAPKs) such as extracellular signal-regulated kinase, c-Jun-N-terminal kinase and p38(MAPK), and inhibition of nuclear factor-κB (NF-κB) pathways including degradation of inhibitor of κB-α and nuclear localization of NF-κB. Taken together, these findings demonstrate the pharmacological roles and molecular mechanisms of DDO in regulating inflammatory responses, and suggest further evaluation and development of DDO as a potent therapeutic agent for the treatment of inflammatory disorders.

[Photosynthesis and oxidative stress of leaves at different positions in Amomum villosum Lour].

Amomum villosum Lour. (Zingeraceae) is a perennial herb that occurs in the understory of tropical and subtropical forests, and is an important medicinal plant. A. villosum, native to Guangdong province, was introduced intentionally to Xishuangbanna, Yunnan province in 1963, and was planted under tropical rainforest. The income from planting A.villosum in rainforest is very important for minority in Xishuangbanna. But now A. villosum fruit yield has decreased greatly due to plant senescence. The senescence mechanism of A. villosum is not known clearly. A. villosum has only one main stem without branch. The leaf age can be estimated by its position at the stem. In this study we measured the variables of photosynthesis and chlorophyll fluorescence, the content of chlorophyll (Chl), Caroteniod, protein and malondialdehyde (MDA), and the activities of antioxidant enzymes of leaves at different positions in A.villosum. We want to know (1) the reasons of leaf photosynthesis decreasing during aging and senescence, and (2) the relationships between oxidative stress and aging/senescence. Leaf age, maximum net photosynthetic rates (P(max)), Chl and soluble protein content increased with the increase of leaf position in A. villosum. P(max) was biggest at the third leaf, while Chl and protein content reached its maximum values at the fifth leaf. They decreased at the 7th leaf, and began to decrease sharply at 9th leaf. MDA content was lower in the first to 7th leaves, and increased greatly at 9th leaf. AQY and F(v)/F(m) began to decrease at 9th leaf too. The results presented above suggested that the third to 5th leaves were mature leaves with vigorous physiological function, the 7th leaf was aging one, the 9th leaf began senescent, the 11th to 15th leaves were senescent. The decrease of Chl and protein content, and stomatal conductance might be the important reason of P(max) decreasing in aging and senescent leaves of A. villosum. NPQ, AQY, F(v)/F(m), Phi(PSII) and q(P) decreased with leaf aging and senescence, which indicated that thermal dissipation decreased, and photoinhibition of photosynthesis intensified. Furthermore, photodamage occurred at the late stage of senescence. But the reducing extent of AQY, F(v)/F(m), Phi(PSII) and q(P) was smaller than that of P(max), indicating that the electrons transported by PSII was more than those used by carbon assimilation. The excessive electron might induce production of reactive oxygen species (ROS). The excessive electron and then ROS were smaller in aging leaf than in senescent leaf. The ROS could be scavenged effectively by antioxidant enzymes and antioxidants in aging leaf, but not in senescent leaf, although the activities of antioxidant enzymes increased significantly. The ROS could results in membrane peroxidation, so MDA content increased, which could intensify leaf senescence further. The results above indicated that aging was not associated with oxidative stress, but senescence was in A. villosum.