Exploring genetic diversity of rice cultivars for the presence of brown planthopper (BPH) resistance genes and development of SNP marker for Bph18

Brown planthopper (BPH) is the most devastating insect pest in rice‐growing areas. Information on availability of BPH resistance alleles and their sources enhances BPH‐resistant breeding programmes. In this study, 260 highly diversified rice cultivars or breeding lines were screened for the presence of five major BPH resistance genes (Bph10, Bph13, Bph18, Bph20 and Bph21) using gene‐specific markers. The analysis revealed that 137 of the 260 cultivars possess at least one BPH resistance gene. Bph10 was predominant while Bph20 was the least distributed. Moreover, two and three different resistance gene combinations were found in the cultivars. Molecular markers play an important role in molecular breeding programmes. A tightly linked PCR‐based co‐dominant Bph18 marker was developed, which is cost effective and time effective and simpler than available Bph18 CAPS marker (7312.T4A). We strongly believe that the identified BPH‐resistant cultivars can be used as alternative resistance gene sources and also as resource for novel BPH resistance genes. The developed Bph18 marker will be highly useful in molecular breeding applications of BPH‐resistant breeding programmes.     

Identification of quantitative trait loci controlling soybean seed weight in recombinant inbred lines derived from PI 483463 (Glycine soja) × ‘Hutcheson’ (G. max)

The objective of this study was to identify quantitative trait loci (QTLs) controlling 100‐seed weight in soybean using 188 recombinant inbred lines (RIL) derived from a cross of PI 483463 and ‘Hutcheson’. The parents and RILs were grown for 4 years (2010–2013), and mature, dry seeds were used for 100‐seed weight measurement. The variance components of genotype (a), environment (e) and a × e interactions for seed weight were highly significant. The QTL analysis identified 14 QTLs explaining 3.83–12.23% of the total phenotypic variation. One of the QTLs, qSW17‐2, was found to be the stable QTL, being identified in all the environments with high phenotypic variation as compared to the other QTLs. Of the 14 QTLs, 10 QTLs showed colocalization with the seed weight QTLs identified in earlier reports, and four QTLs, qSW5‐1, qSW14‐1, qSW15‐1 and qSW15‐2, found to be the novel QTLs. A two‐dimensional genome scan revealed 11 pairs of epistatic QTLs across 11 chromosomes. The QTLs identified in this study may be useful in genetic improvement of soybean seed weight.     

Comparison of single and competitive metal adsorption by pepper stem biochar

Carbon-based sorbents have been proven to be cost-effective in removing pollutants from wastewater. Biochar from plant residue and agricultural waste is an emerging treatment technology. However, there is a limited number of studies on the effects of various biochar sources on metal adsorption. The aim of this study was using batch experiment to evaluate the adsorption of heavy metals in single- and multi-metal conditions onto pepper stem biochar. The maximum adsorption capacities (mg g^?1) of metals by pepper stem biochar were in the order of Pb (131) ? Cr (76) > Cd (67) > Cu (48) > Zn (31) in the single-metal adsorption isotherm and Pb (91) ? Cu (39) > Cr (29) > Zn (20) > Cd (13) in the multi-metal adsorption isotherm. Lead was the most retained cation, whereas Cr and Cd could be easily exchanged and substituted by other metals (Pb or Cu). For pepper stem biochar, the Langmuir model provided a slightly better fit than the Freundlich model. Results from the batch experiments show that competitive adsorption among metals increases the mobility of these metals. Particularly, Cd adsorption capacity in multi-metal conditions was significantly reduced. Overall, the results suggested that competitive adsorption studies are necessary for obtaining an accurate estimation of the metal retention capacity of pepper stem biochar in natural environments.     

Characterization of 12 Novel Microsatellite Markers of Sogatella furcifera (Hemiptera: Delphacidae) Identified From Next-Generation Sequence Data

The white-backed planthopper, Sogatella furcifera (Horváth) (Hemiptera: Delphacidae), is a major pest of rice and has long-range migratory behavior in Asia. Microsatellite markers (simple sequence repeats) have been widely used to determine the origins and genetic diversity of insect pests. We identified novel microsatellite loci for S. furcifera samples collected from Laos, Vietnam, and three localities in Bangladesh from next-generation Roche 454 pyrosequencing data. Size polymorphism at 12 microsatellite loci was verified for 40 adult individuals collected from Shinan, South Korea. The average number of alleles per locus was 7.92. The mean values of observed (H_o) and expected heterozygosities (H_E) were 0.615 and 0.757, respectively. These new microsatellite markers will be a resource for future ecological genetic studies of S. furcifera samples across more broad geographic regions in Asia and may assist in estimations of genetic differentiation and gene flow among populations for implementation of more effective management strategies to control this serious rice pest.     

Xyloketal B Suppresses Glioblastoma Cell Proliferation and Migration in Vitro through Inhibiting TRPM7-Regulated PI3K/Akt and MEK/ERK Signaling Pathways

Glioblastoma, the most common and aggressive type of brain tumors, has devastatingly proliferative and invasive characteristics. The need for finding a novel and specific drug target is urgent as the current approaches have limited therapeutic effects in treating glioblastoma. Xyloketal B is a marine compound obtained from mangrove fungus Xylaria sp. (No. 2508) from the South China Sea, and has displayed antioxidant activity and protective effects on endothelial and neuronal oxidative injuries. In this study, we used a glioblastoma U251 cell line to (1) explore the effects of xyloketal B on cell viability, proliferation, and migration; and (2) investigate the underlying molecular mechanisms and signaling pathways. MTT assay, colony formation, wound healing, western blot, and patch clamp techniques were employed. We found that xyloketal B reduced cell viability, proliferation, and migration of U251 cells. In addition, xyloketal B decreased p-Akt and p-ERK1/2 protein expressions. Furthermore, xyloketal B blocked TRPM7 currents in HEK-293 cells overexpressing TRPM7. These effects were confirmed by using a TRPM7 inhibitor, carvacrol, in a parallel experiment. Our findings indicate that TRPM7-regulated PI3K/Akt and MEK/ERK signaling is involved in anti-proliferation and migration effects of xyloketal B on U251 cells, providing in vitro evidence for the marine compound xyloketal B to be a potential drug for treating glioblastoma.     

Watermelon lycopene β-cyclase: promoter characterization leads to the development of a PCR marker for allelic selection

In the carotenoid biosynthetic pathway, lycopene β-cyclase (LCYB) catalyzes the cyclization that converts lycopene into β-carotene. Only a single copy of LCYB was identified and was suggested to encode a chromoplast-specific LCYB (CYCB type) in watermelon [Citrullus lanatus (Thunb.), Matsum & Nakai]. Splicing variants in the 5′-untranslated region were identified, but alternative splicing did not provide an explanation of the regulation of carotenoid accumulation in watermelon flesh. A quantitative assay using real time-PCR showed that differential expression was not detected between red- and canary yellow-fleshed watermelon cultivars. LCYB promoter regions were isolated and characterized, and a sequence difference was identified in the promoter region between red and canary yellow LCYB alleles. This polymorphism did not change the expression of LCYB, but does provide a reliable marker for discriminating LCYB alleles for red and canary yellow flesh. To develop a PCR-based marker to distinguish between the two LCYB alleles, we designed primers flanking the polymorphic region. The newly developed marker, designated Clcyb.600, co-segregated perfectly with flesh color phenotypes and single nucleotide polymorphism (SNP) markers developed in our previous study. Moreover, the Clcyb.600 marker offers easier discrimination of LCYB alleles than SNP or cleaved amplified polymorphic sequence markers, as it does not require restriction enzyme digestion for genotyping. Genotyping of LCYB promoter alleles in various commercial cultivars and plant introductions indicated that watermelon cultivars can be classified into two groups, those carrying a red LCYB allele or a canary yellow LCYB allele.     

Genotypic difference in spikelet sterility response to air temperature during the reproductive stage of rice

This experiment was conducted to evaluate the varietal differences of spikelet sterility response to air temperature during the reproductive stage. Six rice varieties differing in maturity group (early-maturing; Unkwangbyeo, Odaebyeo, medium-maturing; Andabyeo, Hwasungbyeo, and mid-late maturing; Donganbyeo, Chuchungbyeo) were grown under ambient temperature (AT) conditions before being transferred to the temperature-controlled plastic houses. For the synchronization of the growth stage, 15 rice seedlings (2011) and 10 rice seedlings (2012) per pot were transplanted in a circle and only main stems were grown by removing tillers at early stage of their emergence. At the initial heading stage, pots for each variety were transferred to the four plastic houses that were controlled to AT, AT + 1.5°C, AT + 3.0°C, and AT + 5.0°C, respectively. Spikelet fertility was significantly decreased due to high temperature-induced spikelet sterility at AT + 3.0 and/or AT + 5.0°C treatment during flowering time in 2011. Spikelet fertility in 2012 was much lower than in 2011 even at the AT treatment because of high temperature-induced spikelet sterility at the micosporogenesis stage. Critical temperature (Tc) that induces 50% spikelet sterility at flowering time was estimated by fitting the temperature response of spikelet fertility to a logistic function. Tc ranged from 34.6°C (Odaebyeo) to 39.7°C (Hwasungbyeo), Odaebyeo being significantly more sensitive to high temperature-induced spikelet sterility than the other varieties. This result has shown that response of spikelet sterility to higher temperature is different according to rice varieties. However, further study should be done to arrive at a concrete conclusion.     

Effect of Phlorofucofuroeckol A and Dieckol Extracted from Ecklonia cava on Noise-induced Hearing Loss in a Mouse Model

One of the well-known causes of hearing loss is noise. Approximately 31.1% of Americans between the ages of 20 and 69 years (61.1 million people) have high-frequency hearing loss associated with noise exposure. In addition, recurrent noise exposure can accelerate age-related hearing loss. Phlorofucofuroeckol A (PFF-A) and dieckol, polyphenols extracted from the brown alga Ecklonia cava, are potent antioxidant agents. In this study, we investigated the effect of PFF-A and dieckol on the consequences of noise exposure in mice. In 1,1-diphenyl-2-picrylhydrazyl assay, dieckol and PFF-A both showed significant radical-scavenging activity. The mice were exposed to 115 dB SPL of noise one single time for 2 h. Auditory brainstem response(ABR) threshold shifts 4 h after 4 kHz noise exposure in mice that received dieckol were significantly lower than those in the saline with noise group. The high-PFF-A group showed a lower threshold shift at click and 16 kHz 1 day after noise exposure than the control group. The high-PFF-A group also showed higher hair cell survival than in the control at 3 days after exposure in the apical turn. These results suggest that noise-induced hair cell damage in cochlear and the ABR threshold shift can be alleviated by dieckol and PFF-A in the mouse. Derivatives of these compounds may be applied to individuals who are inevitably exposed to noise, contributing to the prevention of noise-induced hearing loss with a low probability of adverse effects.     

Evidence of Long-Range Transport of Pollutants from the Size-Fractionated Ionic Composition of Aerosols in the Jeju Island of Korea

The ionic composition of total suspended particulate (TSP) and fine (PM_2.5) fractions was investigated from an 1,100 site in the middle of Mt. Halla in Jeju Island, Korea from March to November 2006. The sum concentrations of cation and anion species in TSP fraction were 205 ± 170 and 183 ± 164 neq m^?3, respectively, while those for PM_2.5 as 118 ± 129 and 88.5 ± 89.3 neq m^?3, respectively. In TSP, the concentration of the major ions changed in the order of SO₄ ^2? > NH₄ ⁺ > Ca²⁺ > Na⁺ > NO₃ ^? > Mg²⁺ > K⁺ > Cl^?, while its PM_2.5 counterpart as NH₄ ⁺ > SO₄ ^2? > Ca²⁺ > NO₃ ^? > Na⁺ > Mg²⁺ > K⁺ > Cl^?. Inspection of the temporal variabilities of ionic components indicated that most ions peaked in spring or fall months. The back trajectory analysis showed that the atmospheric composition of the major ionic species was affected fairly sensitively by long-range transport from China under the favorable meteorological conditions. In contrast, the lowest ionic concentration levels were seen most abundantly, when air masses passed from South Sea. Hence, the analysis of ionic concentration data suggests that their distributions are controlled by the combined effects of various source processes including the most prominent Chinese origin and the meteorological condition favorable for such transport.