The sugar beet cyst nematode, Heterodera schachtii, is a major parasite of sugar beet which has been recognized and listed as a quarantine nematode in China and more than 20 countries and regions worldwide.  A survey for important nematodes was undertaken in the sugar beet planting area of China during 2015–2018, and numerous cysts were collected from sugar beet fields in Xinyuan County, Xinjiang Uygur Autonomous Region of China.  The observations of morphological and morphometric characteristics revealed that cysts, vulval cones and second-stage juveniles of the Xinjiang population were in the same range of each other and within those of other reported H. schachtii populations.  Molecular analysis of rDNA-ITS, 28S-D2/D3 and mtDNA cytochrome c oxidase subunit 1 (COI) gene sequences suggested that the Xinjiang population clustered in a branch with those foreign populations, and the sequence similarity was as high as 99.81–100%.  Moreover, this result was confirmed by PCR assay with species-specific primer SHF6 and rDNA2 of H. schachtii, and the pathogenicity test confirmed successful Xinjiang population reproduction in both plant hosts.  In conclusion, based on morphological and molecular characterization, this study confirmed that the cyst nematode population collected from sugar beet fields in Xinjiang is H. schachtii.  As far as we know, this is the first report of H. schachtii on sugar beets in Xinjiang, China.

High nitrate (NO₃⁻) in vegetables, especially in leaf vegetables poses threaten to human health.  Selenium (Se) is an important element for maintaining human health, and exogenous Se application during vegetable and crop production is an effective way to prevent Se deficiency in human bodies.  Exogenous Se shows positive function on plant growth and nutrition uptake under abiotic and/or biotic stresses.  However, the influence of exogenous Se on NO₃⁻ accumulation in hydroponic vegetables is still not clear.  In the present study, hydroponic lettuce plants were subjected to six different concentrations (0, 0.1, 0.5, 5, 10 and 50 µmol L^–1) of Se as Na₂SeO₃.  The effects of Se on NO₃⁻ content, plant growth, and photosynthetic capacity of lettuce (Lactuca sativa L.) were investigated.  The results showed that exogenous Se positively decreased NO₃⁻ content and this effect was concentration-dependent.  The lowest NO₃⁻ content was obtained under 0.5 µmol L^–1 Se treatment.  The application of Se enhanced photosynthetic capacity by increasing the photosynthesis rate (P_n), stomatal conductance (Cs) and the transpiration efficiency (T_r) of lettuce.  The transportation and assimilation of NO₃⁻ and activities of nitrogen metabolism enzymes in lettuce were also analysed.  The NO₃⁻ efflux in the lettuce roots was markedly increased, but the efflux of NO₃⁻ from the root to the shoot was decreased after treated with exogenous Se.  Moreover, Se application stimulated NO₃⁻ assimilation by enhancing nitrate reductase (NR), nitrite reductase (NiR), glutamine synthetase (GS) and glutamate synthase enzyme (GOGAT) activities.  These results provide direct evidence that exogenous Se shows positive function on decreasing NO₃⁻ accumulation via regulating the transport and enhancing activities of nitrogen metabolism enzyme in lettuce.  We suggested that 0.5 µmol L^–1 Se can be used to reduce NO₃⁻ content and increase hydroponic lettuce yield. 

Citrus leaf blotch virus (CLBV) is a member of the genus Citrivirus, in the family Betaflexiviridae.  It has been reported CLBV could infect kiwi, citrus and sweet cherry in China.  Of 289 citrus samples from six regions of China, 15 were detected to be infected with CLBV in this study.  The complete genome of four isolates of CLBV was obtained from Reikou in Sichuan (CLBV-LH), Yura Wase in Zhejiang (CLBV-YL), Bingtangcheng in Hunan (CLBV-BT), Fengjie 72-1 in Chongqing (CLBV-FJ), respectively.  While they all represented 8 747 nucleotides in monopartite size, excluding the poly(A) tail, each of the isolates coded three open reading frames (ORFs).  Identity of the four isolates ranged from 98.9 to 99.8% to each other and from 96.8 to 98.1% to the citrus references in GenBank by multiple alignment of genomes.  A phylogenetic tree based on the genome sequences of available CLBV isolates indicated that the four isolates were clustered together, suggesting that CLBV isolates from citrus in China did not have obvious variation.  This is the first report of the complete nucleotide sequences of CLBV isolates infecting citrus in China.

Male sterility induced by a chemical hybridization agent (CHA) is an important tool for utilizing crop heterosis. Leaves, especially the flag leaves, as CHA initial recipients play a decisive role in inducing male sterility. To investigate effects of different treatment times of CHA-SQ-1 used, morphological, biochemical and physiological responses of wheat flag leaves were detected in this study. CHA induced programmed cell death (PCD) as shown in terminal deoxynucleotidyl transferase-mediated dUTP nick end-labelling (TUNEL) and DNA laddering analysis. In the early phase, CHA-SQ-1 triggered organelle changes and PCD in wheat leaves accompanied by excess production of reactive oxygen species (O2 -. and H2O2) and down-regulation of the activities of superoxide dismutase (SOD), catalase (CAT) and guaiacol peroxidase (POD). Meanwhile, leaf cell DNAs showed ladder-like patterns on agarose gel, indicating that CHA-SQ-1 led to the activation of the responsible endonuclease. The oxidative stress assays showed that lipid peroxidation was strongly activated and photosynthesis was obviously inhibited in SQ-1-induced leaves. However, CHA contents in wheat leaves gradually reduced along with the time CHA-SQ-1 applied. Young flags returned to an oxidative/antioxidative balance and ultimately developed into mature green leaves. These results provide explanation of the relations between PCD and anther abortion and practical application of CHA for hybrid breeding.

   Stripe rust, caused by Puccinia striiformis f. sp. tritici, is an important wheat disease in China, seriously threatening wheat production. Understanding the winter survival of the fungus is a key for predicting the spring epidemics of the disease, which determines the crop loss. Estimation of P. striiformis f. sp. tritici winter survival requires processing a large number of samples for sensitive detection of the pathogen in wheat leaf tissue using real-time quantitative reverse transcription PCR (qRT-PCR). A bottleneck for the analysis is the acquisition of a good yield of high quality RNA suitable for qRT-PCR to distinguish dead and alive fungal hyphae inside leaves. Although several methods have been described in the literatures and commercial kits are available for RNA extraction, these methods are mostly too complicated, expensive and inefficient. Thus, we modified three previously reported RNA extraction methods with common and low-cost reagents (LiCl, SDS and NaCl) to solve the problems and selected the best to obtain high quality and quantity RNA for use in qRT-PCR. In the three improved methods, the NaCl method was proven to be the best for extracting RNA from urediniospores of and wheat leaves infected by P. striiformis f. sp. tritici, although the modified LiCl and SDS methods also increased yield of RNA compared to the previous methods. The improved NaCl method has the following advantages: 1) Complete transfer of urediniospores of P. striiformis f. sp. tritici from the mortar and pestle can ensure the initial amount of RNA for the qRT-PCR analysis; 2) the use of low-cost NaCl to replace more expensive Trizol can reduce the cost; 3) the yield and quality of RNA can be increased; 4) the improved method is more suitable for a large number and high quantity of samples from fields. Using the improved NaCl method, the amount of RNA was increased three times from urediniospores of P. striiformis f. sp. tritici compared from the extraction kit. Approximately, 10.11 μg total RNA of high quality was obtained from 100 mg of infected leaves, which was 8.8, 6.5, 3.4 and 2.1 folds of the amounts obtained from the previous LiCl, SDS, NaCl and traditional Trizol methods, respectively. The method could be used to study the overwintering rates of P. striiformis f. sp. tritici over a large region of wheat production for predicting epidemic levels by determining pathogen survival levels after winter. The method can also be used in any studies which need a large number of high quality RNA samples.

Soybean is a widely planted genetically modified crop around the world. However, it is still one of the most recalcitrant crops for genetic transformation due to the difficulty of regeneration via organogenesis and some factors that affect the transformation efficiency. The percentages of resistant bud formation and transient expression efficiency are important indexes reflecting the regeneration and transformation efficiency of soybean. In this study, the percentages of resistant bud formation and transient expression of β-glucuronidase (GUS) were compared after treatment with sonication or surfactant and co-treatment with both. The results showed that treatment with either sonication or surfactant increased the percentage of resistant bud formation and transient expression efficiency. The highest percentages were acquired and significantly improved when cotyledon node explants were co-treated with sonication for 2 s and surfactant at 0.02% (v:v) using two different soybean genotypes, Jack and Zhonghuang 10. The improved transformation efficiency of this combination was also evaluated by development of herbicide-tolerant soybeans with transformation efficiency at 2.5–5.7% for different genotypes, which was significantly higher than traditional cotyledonary node method in this study. These results suggested that co-treatment with surfactant and sonication significantly improved the percentages of resistance bud formation, transient expression efficiency and stable transformation efficiency in soybean.

Higher boll worm survival rates were detected after high temperature presented during square period in Bt cotton. The objective of this study was to investigate the effects of high temperature level on the Bt efficacy of two different types of Bt cotton cultivars at squaring stage. During the 2011 to 2013 cotton growth seasons, high temperature treatments ranged from 34 to 44°C in climate chambers, and field experiments under high temperature weather with various temperature levels were conducted to investigate the effects of the high temperature level on square Bt protein concentration and nitrogen metabolism. The climate chamber experiments showed that the square insecticidal protein contents reduced after 24 h elevated temperature treatments for both cultivars, whereas significant declines of the square insecticidal protein contents were detected at temperature >38°C, and only slightly numerical reductions were observed when temperature below 38°C. Similar high temperature responses were also observed at the two field experimental sites in 2013. Correspondingly, high temperature below 38°C seems have little effect on the square amino acid concentrations, soluble protein contents, glutamic- pyruvic transaminase (GPT) and glutamic-oxalacetic transaminase (GOT) activities as well as protease and peptidase activities; however, when the temperature was above 38°C, reduced soluble protein contents, enhanced amino acid concentrations, decreased GPT and GOT activities, bolstered protease and peptidase activities in square were detected. In general, the higher the temperature is (>38°C), the larger the changes for the above compound contents and key enzymes activities of the square protein cycle. The findings indicated that the unstable insect resistance of the square was related to high temperature level during square stage.

Soybean seed storage protein is one of the most important plant vegetable proteins, and β subunit is of great significance to enhance soybean protein quality and processing property. F2 segregated population and residual heterozygous lines (RHL) derived from the cross between Yangyandou (low level of β subunit) and Zhonghuang 13 (normal level of β subunit) were used for mapping of β subunit content. Our results showed that β subunit content was controlled by a single dominant locus, qBSC-1 (β subunit content), which was mapped to a region of 11.9 cM on chromosome 20 in F2 population of 85 individuals. This region was narrowed down to 2.5 cM between BARCSOYSSR_20_0997 and BARCSOYSSR_20_0910 in RHL with a larger population size of 246 individuals. There were 48 predicted genes within qBSC-1 region based on the reference genome (Glyma 1.0, Williams 82), including the two copies of β subunit coding gene CG4. An InDel marker developed from a thymine (TT) insertion in one copy of CG4 promoter region in Yangyandou cosegregrated with BARCSOYSSR_20_0975 within qBSC-1 region, suggesting that this InDel marker maybe useful for marker-assisted selection (MAS).

Thirty-two Wistar rats were divided randomly into four groups of eight with six females and two males in each group. The rats were exposed to high fluoride drinking water (45 mg F- L-1 from 100 mg NaF L-1), low dietary iodine (0.0855 mg kg-1), or both together in order to assess the effects of these three regimens on the thyroid function of the offspring rats. After the animal model was established, the offspring rats were bred and 10-, 20-, 30-, 60-, and 90-d-old rats were used for the experiment. The treatments for the offspring rats were the same as those of their parents. In comparison with control rats, the relative thyroid glands were changed by three regimens, but the mean values of thyroid weight in the experimental groups saw no marked difference. Serum TT3 levels were increased in all stages in the low iodine (LI) group. In the high fluoride (HiF) group, increase in TT3 levels was observed except in 20-d-old rats. Decrease in TT3 at 20- and 90-d and increase in TT3 at 30- and 60-d were found in HiF+LI group. Serum TT4 levels first saw an increase, and then dropped in the LI and HiF+LI group. However, an increase in TT4 was found in the HiF group. The levels of TSH in serum rocketed at d 20, and then dropped in the next stages in experimental groups. The results suggested that thyroid disorder could be induced by high flroride in drinking water, low iodine diet, or both of them. Exposure time to fluoride or low iodine diet was one of the important factors that fluoride can induce the development of thyroid dyfunction.

Breeding of male-sterile lines has become the mainstream for the heterosis utilization in foxtail millet, but the genetic basis of most male-sterile lines used for the hybrid is still an area to be elucidated. In this study, a highly male-sterile line Gao146A was investigated. Genetic analysis indicated that the highly male-sterile phenotype was controlled by a single recessive gene a single recessive gene. Using F2 population derived from cross Gao146A/K103, one gene controlling the highly male- sterility, tentatively named as ms1, which linked to SSR marker b234 with genetic distance of 16.7 cM, was mapped on the chromosome VI. These results not only laid the foundation for fine mapping of this highly male-sterile gene, but also helped to accelerate the improvement of highly male-sterile lines by using molecular marker assisted breeding method.