English (United Kingdom)

https://curated-unify.zendy.io/wp-json/zendy-region/v1/featured_content/oa?rat=en

https://curated-unify.zendy.io/wp-json/zendy-region/v1/highlighted_journal/

Global: Zendy Plus annual

Presents the access of premium content as premium feature

Premium Content

Presents the keyphrase highlighting as premium feature

Keyphrase Highlighting

Presents the summarisation as premium feature

Summarisation

Insights

Presents the pdf analysis as premium feature

PDF Analysis

Presents the zaia usage as premium feature

ZAIA

Global: Zendy Tools annual

Global: Zendy Free Plan

Global: Zendy Tools monthly

Global: Zendy Plus monthly

As a rare, endemic, important, and salt-sensitive medicinal plant species in China, Cynanchum bungei Decne seeds were treated to germinate with distilled water (control) or NaCl solutions in the presence or absence of nitric oxide (NO) donor sodium nitroprusside (SNP) to investigate the effects of exogenous NO on seed germination, seedling growth, and antioxidant enzyme activities under salt stress. Sixty mM NaCl significantly inhibited the germination and seedling growth of C. bungei. Exogenous SNP alleviated salt stress in a dose-dependent manner, as indicated by accelerating the seed germination, increasing germination index (GI), vigor index (VI), germination velocity (GV), shoot height (SH), taproot length (TL), shoot biomass (SB), root biomass (RB) as well as shortening mean germination time (MGT), and 0.1 mM SNP was the optimal concentration. SNP at 0.1 mM greatly increased the activities of superoxide dismutase (SOD) and catalase (CAT) under salt stress, which contributed to alleviate the oxidative stress induced by salt stress in C. bungei seeds. It is concluded that NO treatment is an effective practice to improve C. bungei seed germination under saline condition. Soil salinity is a major limiting factor for agricultural land productivity. At least 20% of all irrigated lands in the world are salt-affected with some estimates being as high as 50% (Pitman and Läuchli, 2002). In China, there is a total area of 3.47 · 10 ha saline soil (Liu et al., 2008), and sodium chloride is the most common and thus the most troublesome salt composition. Although the salinity inhibition effects on plant growth vary at different stages, the first exposure and the most vulnerable phase of the plant to salinity stress usually occurs at germination and seedling stages. Thus, it is worthwhile to clear the influence mechanisms of salt stress on seed germination. Then suitable measures should be developed to improve seed germination, and thereby plant establishment, on saline soils. Salt stress can impose both ionic toxicity and osmotic stress on plants, which lead to nutritional imbalance and oxidative stress caused by reactive oxygen species (ROS) (Zhu, 2003). ROS are key components of signaling networks to regulate developmental processes (Kranner and Seal, 2013). However, the excess of ROS can damage macromolecular and cellular structure (Kranner and Seal, 2013), and as a result, plant cells have developed different strategies to regulate their intracellular ROS concentrations by scavenging of ROS. Major ROS scavenging enzymes include SOD, peroxidase (POD), CAT, and ascorbate peroxidase (APX). Therefore, enhancing the activity of antioxidant enzymes in plant organs is necessary for improving a plant’s tolerance to salt stress. NO, as a crucial signaling molecule, is involved in multiple biological functions in plants. These include stimulation of seed germination (Sarath et al., 2006), modulation of plant growth and development (Gouvêa et al., 1997), regulation of plant maturation and senescence (Liao et al., 2013), suppression of floral transition (He et al., 2004), mediation of stomatal movement (Liu et al., 2003), and involvement of light-mediated greening (Zhang et al., 2006). NO has also been involved in responses to abiotic and biotic stresses such as drought (Fan and Liu, 2012), salt (Boldizsár et al., 2013), heat (Song et al., 2006a), and metal stresses (He et al., 2014), disease resistance (Asai et al., 2010), apoptosis (Pedroso et al., 2000), and ultraviolet-B radiation (Chen et al., 2003). NO effects on seed germination under salinity stress were confirmed in wheat (Duan et al., 2007), maize (Boldizsár et al., 2013), soybean (Vaishnav et al., 2013), cucumber (Fan et al., 2013a, 2013b), reed (Zhao et al., 2004), Ababidopsis (Zhao et al., 2007), etc. Cynanchum bungei Decne (Baishouwu in China), a member of the Asclepiadaceae family, is a perennial climbing shrub distributed in China. Its root has been used as a tonic medicine or health food for centuries in traditional Chinese medicine. C. bungei has useful activities including the antitumor and immune regulatory effect and is non-toxic (Gao et al., 2005). As a rare, endemic, and beneficial species, C. bungei is becoming more and more precious not only in China, but also in other countries such as Japan and Korea (Song et al., 2006b). With the increasing demand for this endangered wild resources (Zhang et al., 2010), seed propagation has already been used to solve supply and demand, protect germplasm resource, and enrich genetic diversity of this species (Zhang, 2012). The existing study showed C. bungei is sensitive to salt stress, especially during germination and as a seedling (Wang et al., 2012). Here, we suppose that exogenous NO application under salt stress can have a positive effect on C. bungei seed germination. In this article, the effects of exogenous NO treatment on seed germination, seedling growth, and antioxidant enzyme activity of C. bungei under salt stress were investigated to test the feasibility of this assumption. Meanwhile, the expected results would also suggest SNP, a NO donor, to be used as a seed coating to increase C. bungei seedling tolerance to salt stress. Materials and Methods Seed source. Seeds of C. bungei were collected from the north-facing slope of Mount Tai (lat. 36 15#17$ N, long. 117 06#15$ E) in late fall and winter of 2012. Seeds were airdried at room temperature and stored in darkness at 4 C until Apr. 2013. Experimental procedures. Germination tests were performed from May to Sept. 2013. Seeds were immersed in 75% ethanol for 5 min and then 5% sodium hypochlorite for 5 min for surface sterilization and then rinsed three times with deionized water and dried on filter paper. Our preliminary experiment had shown that 60 mM NaCl decreased germination of C. bungei seeds 40%. Based on this, 60 mM NaCl was used to induce salinity stress in this study. The treatments were as follows: distilled water [control (CK)], 60 mM NaCl, 60 mM NaCl + 0.01 mM SNP, 60 mM NaCl + 0.1 mM SNP, 60 mM NaCl + 0.5 mM SNP, and 60 mM NaCl + 1.0 mM SNP. Each treatment was replicated six times. Thirty-six seeds per treatment were placed in petri dishes (12 cm diameter · 1.5 cm depth) containing filter paper moistened with 10 mL of treatment solutions and germinated in incubators (HPG-280BX; Harbin Donglian Electronic Technology Development Ltd., Harbin, China) at 20 C and a 12:12-h photoperiod (Zhang, 2012). The treatment solutions were renewed each day to maintain unaltered concentrations. The dishes were rearranged daily to avoid effects of potential temperature and light differences or gradients in the incubators. Germination performance was estimated according to the rate of germinated seeds. Received for publication 5 Sept. 2014. Accepted for publication 18 Nov. 2014. I gratefully acknowledge financial support from the National Natural Science Foundation of China (31101100), Shandong Province Science and Technology Development Plan (2014GNC111001), and Innovation Team with High Water Use Efficiency of Dryland Crops in Shandong Province. To whom reprint requests should be addressed; e-mail hyzhang608@126.com. HORTSCIENCE VOL. 50(1) JANUARY 2015 119 Seeds were considered germinated when the radical had protruded through the seed coat. Final germination percentage (FGP) is the rate of germinated seeds on the 15th day. On the 20th day, SH and TL were measured. The shoot and roots of each seedling were dried at 60 C for 48 h to quantify SB and RB. A series of parameters were as follows. Germination index; GI = XGt

Nitric Oxide Alleviates the Inhibition of Salinity Stress on Seed Germination and Seedling Growth of Cynanchum bungei Decne (Asclepiadaceae)