Antioxidant enzyme activity and microRNA are associated with growth of Poa pratensis callus under salt stress

Luo Hongsong,Zhou Zhixiang,Song Guilong,Yao Hongxiang,Han Liebao 한국식물생명공학회 2020 Plant biotechnology reports Vol.14 No.4

Kentucky bluegrass (Poa pratensis L.) is an important species of turfgrass that is commonly planted on golf courses and landscapes all over the world. It is sensitive to salt stress; however, details relating to its molecular mechanisms of salt resistance are not available. We, therefore, analyzed the changes in growth, antioxidant enzyme activity, and microRNA expression in the callus 1 week after treatment with 200 mM NaCl for 12 h, 24 h, 48 h, 96 h, and 144 h. The results demonstrated that callus growth declined and thiobarbituric acid-reactive substance production and cell membrane permeability increased. Treatment with salt increased ascorbate peroxidase, glutathione reductase, superoxide dismutase, catalase, peroxidase, and polyphenol oxidase activity. Changes in the expression levels of microRNAs were observed under salt treatment. The expression of miR162, miR173, miR391, miR408, miR773, and miR857 increased by 70% after 24 h of salt treatment, after which it declined to a level similar to that of the control. The expression level of miR775 and miR827 decreased by 20% after 24 h, and then further decreased by 80% after 144 h. The expression level of miR841 increased by 50% after 24 h of salt treatment, and then stabilized. In contrast, salt treatment increased the expression of the auxin response factors ARF6, ARF8, ARF10, and ARF16 in the callus from 12 to 144 h of salt treatment, during which the expression increased twofold. Gene expression analysis indicated that salt-responsive gene families were regulated by microRNAs in the callus under salinity stress. The activity of antioxidant enzymes is also changing. MiR841 is considered to be a positive regulator of antioxidant enzyme biosynthesis. The present investigation elucidates the manner in which P. pratensis responds to salt stress in the callus, and could be used to inform further studies on the molecular mechanisms of stress tolerance.

A Comparative Study on the Offshore Intensification of Supertyphoon Rammasun (2014) and Typhoon Rumbia (2013): the Role of Summer Monsoon

Zhixiang Xiao,Cai Yao,Xiaoli Luo,Hongmei Sun 한국기상학회 2021 Asia-Pacific Journal of Atmospheric Sciences Vol.57 No.3

The offshore intensificationmechanisms of Supertyphoon Rammasun (2014) and Typhoon Rumbia (2013) are analyzed and compared based on the best track typhoon data provided by the Shanghai Typhoon Institute of China Meteorological Administration (STI/CMA), ECMWF (CMA and JMA) objective (subjective) predicted typhoon track and intensity, and reanalysis data of the National Centers for Environmental Prediction/National Center for Atmospheric Research (NCEP/NCAR). Results show that the offshore sea surface temperature over 28 °C was conducive to the intensification of the two typhoons in the coastal area prior to their landfall in South China. Rammasun was embedded in an extremely active phase of a 10–20-day oscillation in the summer monsoon over the South China Sea and western North Pacific prior to its landfall. The low-level jet transported warm and moist air to the inner core of Rammasun and the deepening of the southwesterly monsoon flow up to 200 hPa reduced vertical wind shear, both favorable for the offshore rapid intensification of Rammasun. In 2013, the summer monsoon over the South China Sea and western North Pacific experienced quasi-20-day and quasi-10-day oscillations. The out of phase of the two oscillations resulted in relatively weak tropical and subtropical summer monsoon flow prior to the landfall of Rumbia. As a result, the low-level monsoon flow transported relatively less moist air into Rumbia, and the shallow monsoon flow was not conducive to the weakening of vertical wind shear, resulting in a less rapid offshore intensification of Rumbia than Rammasun.

Research on influence of harmonic wear wheel on wheel/rail contact geometry of high-speed train

Qian Xiao,Zhixiang Luo,Xu Xu,Jifeng Zheng,Shu Cheng 대한기계학회 2019 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.33 No.2

Harmonic wear is one of the common wear phenomena of high-speed train wheels. The change of wheel/rail rolling contact geometry leads to unstable characteristics of wheel/rail contact, which directly affects the quality and safety of high-speed train operation. Because wheelset lateral displacement directly affected the wheel/rail contact geometry, in this paper, the UM software was used to establish a high-speed train vehicle-track coupled dynamics simulation model of the CRH2 (China Railway High-speed 2) head car. Lateral displacement of harmonic wear wheel was calculated under different wear condition to analyze the influence of harmonic wear wheels on wheelset lateral displacement. Then according to macroscopic dimension change of the wheel profile from lateral and radial directions of high-speed train induced by harmonic wear wheels, wheel profiles under different wear condition were selected. And wheel/rail contact geometry under different harmonic wear stages was calculated to discuss the influence of harmonic wear wheel on wheel/rail contact geometry. The results show that harmonic order and wave depth of harmonic wear wheel have small influence on the lateral displacement of wheelset, but the influence of wave depth is greater than harmonic order. The average difference of lateral displacement between harmonic wear wheel and no harmonic wear wheel increases with the increase of wave depth and order. In a harmonic wave length, the maximum value of both equivalent conicity and contact angle appear in deepest wave depth. The greater the wave depth, the more obvious the fluctuations, and equivalent conicity changes are less obvious.

High-performance broadband heterojunction photodetectors based on multilayered PtSe₂ directly grown on a Si substrate

Xie, Chao,Zeng, Longhui,Zhang, Zhixiang,Tsang, Yuen-Hong,Luo, Linbao,Lee, Jung-Ho The Royal Society of Chemistry 2018 Nanoscale Vol.10 No.32

<P>Two-dimensional group-10 transition metal dichalcogenides have recently attracted increasing research interest because of their unique electronic and optoelectronic properties. Herein, we present vertical hybrid heterojunctions of multilayered PtSe2 and Si, which take advantage of large-scale homogeneous PtSe2 films grown directly on Si substrates. These heterojunctions show obvious rectifying behavior and a pronounced photovoltaic effect, enabling them to function as self-driven photodetectors operating at zero bias. The photodetectors can operate in both photovoltage and photocurrent modes, with responsivity values as high as 5.26 × 10<SUP>6</SUP> V W<SUP>−1</SUP> and 520 mA W<SUP>−1</SUP> at 808 nm, respectively. The <I>I</I>light/<I>I</I>dark ratio, specific detectivity, and response speed are 1.5 × 10<SUP>5</SUP>, 3.26 × 10<SUP>13</SUP> Jones, and 55.3/170.5 μs, respectively. Furthermore, the heterojunctions are highly sensitive in a broad spectral region ranging from deep ultraviolet to near-infrared (NIR) (200-1550 nm). Because of the strong NIR light absorption of PtSe2, the heterojunctions exhibit photocurrent responsivities of 33.25 and 0.57 mA W<SUP>−1</SUP> at telecommunication wavelengths of 1310 and 1550 nm, respectively. Considering the excellent performance of the PtSe2/Si heterojunctions, they are highly suitable for application in high-performance broadband photodetectors. The generality of the above results also signifies that the proposed <I>in situ</I> synthesis method has great potential for future large-scale optoelectronic device integration.</P>

Physiological and metabolic responses to nitrogen availability of rice (Oryza sativa L.) cultivars with differ in nitrogen efficient

Ruan Xinmin,Du Hongyang,Zhan Xinchun,Cong Xihan,Shi Fuzhi,Li Juan,Luo Zhixiang,Dong Zhaorong 한국식물생명공학회 2023 Plant biotechnology reports Vol.17 No.1

Developing genotypes with high-nitrogen use efficiency is a prerequisite for achieving sustainable agriculture and high yields. In this study, both physiological and metabolic analyses were performed to evaluate the NUE (nitrogen use efficiency) of two elite indica rice cultivars: OM052 and Huanghuazhan (HHZ). The pNUE and gNUE of OM052 were higher than HHZ under three N conditions, and significant (p < 0.05) especially under both LN and MN conditions. The contents of soluble sugar and malate were significantly different between OM052 and HHZ under LN and HN conditions. The GDH activity in OM052 was significantly high than that in HHZ under HN condition. Metabolic analyses showed that 136 and 142 differentially accumulating metabolites were identified between OM052 and HHZ under LN and HN conditions, respectively. KEGG analysis showed that ‘aminoacyl-tRNA biosynthesis’ was also the most significant enriched in LN_OM052 vs. LN_ HHZ and ‘Glyoxylate and dicarboxylate metabolism’ and ‘citrate cycle’ were the most significantly enriched in HN_OM052 vs. HN_ HHZ. The contents of four metabolites (cis-aconitate, isocitrate, fumarate, and malate) involved in the TCA cycle were significantly upregulated in HN condition compared with LN condition, regardless of OM052 and HHZ. Taken together, the results of our study revealed the physiological and metabolic differences underlying the OM052 and HHZ and provide new insights into coordinating C and N metabolism and improving the NUE of rice.