Exogenous abscisic acid prolongs the dormancy of recalcitrant seed of Panax notoginseng.

The seeds of Panax notoginseng (Burk.) F. H. Chen are typically characterized by their recalcitrance and after-ripening process and exhibit a high water content at harvest as well as a high susceptibility to dehydration. Storage difficulty and the low germination of recalcitrant seeds of P. notoginseng are known to cause an obstacle to agricultural production. In this study, the ratio of embryo to endosperm (Em/En) in abscisic acid (ABA) treatments (1 mg·l-1 and 10 mg·l-1, LA and HA) was 53.64% and 52.34%, respectively, which were lower than those in control check (CK) (61.98%) at 30 days of the after-ripening process (DAR). A total of 83.67% of seeds germinated in the CK, 49% of seeds germinated in the LA treatment, and 37.33% of seeds germinated in the HA treatment at 60 DAR. The ABA, gibberellin (GA), and auxin (IAA) levels were increased in the HA treatment at 0 DAR, while the jasmonic acid (JA) levels were decreased. ABA, IAA, and JA were increased, but GA was decreased with HA treatment at 30 DAR. A total of 4,742, 16,531, and 890 differentially expressed genes (DEGs) were identified between the HA-treated and CK groups, respectively, along with obvious enrichment in the ABA-regulated plant hormone pathway and the mitogen-activated protein kinase (MAPK) signaling pathway. The expression of pyracbactin resistance-like (PYL) and SNF1-related protein kinase subfamily 2 (SnRK2s) increased in the ABA-treated groups, whereas the expression of type 2C protein phosphatase (PP2C) decreased, both of which are related to the ABA signaling pathway. As a result of the changes in expression of these genes, increased ABA signaling and suppressed GA signaling could inhibit the growth of the embryo and the expansion of developmental space. Furthermore, our results demonstrated that MAPK signaling cascades might be involved in the amplification of hormone signaling. Meanwhile, our study uncovered that the exogenous hormone ABA could inhibit embryonic development, promote dormancy, and delay germination in recalcitrant seeds. These findings reveal the critical role of ABA in regulating the dormancy of recalcitrant seeds, and thereby provide a new insight into recalcitrant seeds in agricultural production and storage.

Photosynthesis, light energy partitioning, and photoprotection in the shade-demanding species Panax notoginseng under high and low level of growth irradiance.

Partitioning of light energy into several pathways and its relation to photosynthesis were examined in a shade-demanding species Panax notoginseng (Burkill) F.H.Chen ex C.Y.Wu & K.M.Feng grown along a light gradient. In fully light-induced leaves, the actual efficiency of PSII photochemistry (ΔF/Fm'), electron transport rate (ETR), non-photochemical quenching (NPQ) and photochemical quenching (qP) were lower in low-light-grown plants; this was also the case in fully dark-adapted leaves under a simulated sunfleck. In response to varied light intensity, high-light-grown plants showed greater quantum yields of light-dependent non-photochemical quenching (ΦNPQ) and PSII photochemistry (ΦPSII) and smaller quantum yields of fluorescence and constitutive thermal dissipation (Φf,d). Under the simulated sunfleck, high-light-grown plants showed greater ΦPSII and smaller Φf,d. There were positive relationships between net photosynthesis (Anet) and ΦNPQ+f,d and negative relationships between Anet and ΦPSII in fully light-induced leaves; negative correlations of Anet with ΦNPQ+f,d and positive correlations of Anet with ΦPSII were observed in fully dark-adapted leaves. In addition, more nitrogen was partitioned to light-harvesting components in low-light-grown plants, whereas leaf morphology and anatomy facilitate reducing light capture in high-light-grown plants. The pool of xanthophyll pigments and the de-epoxidation state was greater in high-light-grown plants. Antioxidant defence was elevated by increased growth irradiance. Overall, the evidences from P. notoginseng suggest that in high-light-grown shade-demanding plants irradiated by high light more electrons were consumed by non-net carboxylative processes that activate the component of NPQ, that low-light-grown plants correspondingly protect the photosynthetic apparatus against photodamage by reducing the efficiency of PSII photochemistry under high light illumination, and that during the photosynthetic induction, the ΔpH-dependent (qE) component of NPQ might dominate photoprotection, but the NPQ also depresses the enhancement of photosynthesis via competition for light energy.

[Study on HPLC characteristic fingerprint of Yunnan Dipsacus asper].

OBJECTIVE: To study the HPLC fingerprint of yunnan Dipsacus asper and provide a reliable method for sciencetific evaluation and quality control. METHODS: 16 batches of Dipsacus asper were collected from 11 counties (cities, districts) of 5 prefectures or municipals in Yunnan provinice, which were the mainly distribution region of Dipsacus asper. Samples were analyzed on an Aglient Zorbax SB-18 (4.6 mm x 250 mm, 5 microm) eluted with methanol (A) and water (B) as mobile phase in gradient clution. The flow rate was 1 ml/min, and the column temperature was set at 38 degrees C. The detector wavelength was 220 nm. RESULTS: A HPLC fingerprint method was established, 14 common peaks were selected and the similarity ranged from 0.674 to 0.965, cluster analysis could classified these 16 batches of Dipsacus asper into 2 groups. CONCLUSION: Dipsacus japonicus is found for the first time in yunnan. The fingerprint of Dipsacus asper in different origin have a extremely high similarity;The method is accurate and reliable.

[Effects of different light and GA3 on the germination and seedling growth of Rhodiola sachalinensis].

OBJECTIVE: To improve germination rate and research the seed germination character of Rhodiola sachalinensis. METHODS: Made seed germinated under water or with moisture, at light or dark condition, effects of 6 different light qualities (black, white, blue, green, red and far red light) illumination on seed germination were studied. The seedling growth at different temperature were studied as well. RESULTS: The results indicated that light was required for Rhodiola sachalinensis seeds germinate, 83.3% germination rate at light and soaking in watercondition; Seed germination were improved to 84%, 70.7% and 52.0% respectively in white, red and green light quality illumination, the germination rate reached 84% after 9 h of white light illumination. Germination rate were 80% after 100 mg/L GA3 treatment for 3 h under dark condition. 20 degrees C was the optimal temperature for Rhodiola sachalinensis seedling growth, under with the plant height, fresh weight and dry weight of plant were the best. Seedling growth rate and the dry weight increased obviously at 35 d and 50 d. CONCLUSION: The experiment definited the best condition for Rhodiola sachalinensis seed germination and seedling growth, supplied basic data for large scale planting Rhodiola sachalinensis using seed propagation technology.

[Molluscicidal effect of endophyte LL3026 from Buddleia lindleyana against Oncomelania hupensis].

OBJECTIVE: To research the molluscicidal effect, active components, thermal stability and light stability of endophyte LL3026 (Colletotrichum sp.) from Buddleia lindleyana METHODS: The molluscicidal effect of LL3026 against Oncomelania hupensis was determined as referring to the WHO guidelines for laboratory molluscicidal test, and the control experiments were performed with 1 mg/L niclosamide or dechlorinated tap water. The active components from LL3026 were extracted by different polar solvents. The thermal stability and light stability of its extracellular moiety was examined at different temperature (30-100 degrees C), different time (30-150 min) and different illumination time (1-9 d). RESULTS: Immersion test showed that the LC50 values for the LL3026 broth were 50.11, 3.43, and 1.55 mg/L for 24, 48, and 72 h, respectively. The ether extract of LL3026 broth showed the best molluscicidal activity compared with other fractions. Treated with 25 mg/L ether extract for 24, 48, and 72 h, the mortality of O. hupensis was 100%. The molluscicidal activity of LL3026 broth had no change at 80 degrees C for 120 min, and the snail mortality was 100%. A 48-h exposure to LL3026 broth which placed in an artificial climate box with 3 600 1x illumination for 9 d resulted in 86.7% snail mortality. CONCLUSION: The fractions extracted from endophyte LL3026 isolated from B. lindleyana shows molluscicidal effect to O. hupensis.

[Study on molluscicidal effect of the extracts from sarcotesta of Ginkgo biloba].

OBJECTIVE: To observe the molluscicidal activity and the fish acute toxicity of the molluscicides extracted from Ginkgo biloba sarcotesta by benzinum (EGSB) (with major component of ginkgolic acid), arecoline (ARE) and their combination. METHODS: Oncomelania hupensis snails were immersed in different concentrations of dry powder sarcotesta of Ginkgo biloba (DPGB), extract of Ginkgo biloba sarcotesta by water (EGSW) and EGSB by WHO recommended method for molluscicide screening to observe the molluscicidal activity, and also the inhibiting effect on the snails' climbing-up as well as acute toxicity to Brachydanio rerio. Niclosamide was used as control. RESULTS: The three extractions from Ginkgo biloba all showed molluscicidal activity, with EGSB as the best. Its 24 h LC50 and LC90 were 0.65 mg/L and 5.50 mg/L, and the 48 h LC50 and LC90 were 0.07 mg/L and 0.85 mg/L, respectively. The combination of EGSB and ARE showed better effect than EGSB alone. Its 24 h LC50 and LC90 were 0.26 mg/L and 0.56 mg/L respectively, a sharp decrease by 60% and 90% compared to EGSB (P<0.05). Under the concentration of 2.50 mg/L of EGSB, the rate of snails' climbing-up was 10%, while under the concentration of 0.16 mg/L of the EGSB+ARE combination, the rate was 8%. The inhibition on the snails' climbing-up of the combination was stronger than EGSB. The fish survived for 24 h and 10th respectively at the concentration of 1 x LC90 and 2 x LC90 of EGSB. Under the concentration of 2 x LC90 of the combination, only 50% of the fish died and no fish died at the concentration of 1 x LC90. The toxicity of the combination was lower than EGSB alone. CONCLUSION: EGSB shows an adequate molluscicidal activity and it is worth of further investigation.