Biological control of potato common scab and growth promotion of potato by Bacillus velezensis Y6.

Potato common scab, caused mainly by Streptomyces scabies, causes surface necrosis and reduces the economic value of potato tubers, but effective chemical control is still lacking. In this study, an attempt was made to control potato common scab by inoculating potatoes with Bacillus velezensis (B. velezensis) and to further investigate the mechanism of biological control. The results showed that B. velezensis Y6 could reduce the disease severity of potato common scab from 49.92 ± 25.74% [inoculated with Streptomyces scabies (S. scabies) only] to 5.56 ± 1.89% (inoculated with S. scabies and Y6 on the same day) and increase the potato yield by 37.32% compared with the control under pot experiment in this study. Moreover, in the field trial, it was found that Y6 could also significantly reduce disease severity from 13.20 ± 1.00% to 4.00 ± 0.70% and increase the potato yield from 2.07 ± 0.10 ton/mu to 2.87 ± 0.28 ton/mu (p < 0.01; Tukey's test). Furthermore, RNA-seq analysis indicated that 256 potato genes were upregulated and 183 potato genes were downregulated in response to B. velezensis Y6 inoculation. In addition, strain Y6 was found to induce the expression of plant growth-related genes in potato, including cell wall organization, biogenesis, brassinosteroid biosynthesis, and plant hormone transduction genes, by 1.01-4.29 times. As well as up-regulate hydroquinone metabolism-related genes and several transcription factors (bHLH, MYB, and NAC) by 1.13-4.21 times. In summary, our study will help to understand the molecular mechanism of biological control of potato common scab and improve potato yield.

Transcriptome profiling of genes regulated by phosphate-solubilizing bacteria Bacillus megaterium P68 in potato (Solanum tuberosum L.).

The insoluble phosphorus in the soil is extremely difficult to be absorbed and used directly through the potato root system. Although many studies have reported that phosphorus-solubilizing bacteria (PSB) can promote plant growth and uptake of phosphorus, the molecular mechanism of phosphorus uptake and growth by PSB has not been investigated yet. In the present study, PSB were isolated from rhizosphere soil in soybean. The data of potato yield and quality revealed that the strain P68 was the most effective In the present study, PSB identification, potato field experiment, pot experiment and transcriptome profiling to explored the role of PSB on potato growth and related molecular mechanisms. The results showed that the P68 strain (P68) was identified as Bacillus megaterium by sequencing, with a P-solubilizing ability of 461.86 mg·L-1 after 7-day incubation in National Botanical Research Institute's Phosphate (NBRIP) medium. Compared with the control group (CK), P68 significantly increased the yield of potato commercial tubers by 17.02% and P accumulation by 27.31% in the field. Similarly, pot trials showed that the application of P68 significantly increased the biomass, total phosphorus content of the potato plants, and available phosphorus of the soil up by 32.33, 37.50, and 29.15%, respectively. Furthermore, the transcriptome profiling results of the pot potato roots revealed that the total number of bases was about 6G, and Q30 (%) was 92.35-94.8%. Compared with the CK, there were a total of 784 differential genes (DEGs) regulated when treated with P68, which 439 genes were upregulated and 345 genes were downregulated. Interestingly, most of the DEGs were mainly related to cellular carbohydrate metabolic process, photosynthesis, and cellular carbohydrate biosynthesis process. According to the KEGG pathway analysis, a total of 46 categorical metabolic pathways in the Kyoto Encyclopedia of Genes and Genomes (KEGG) database were annotated to 101 DEGs found in potato roots. Compared with the CK, most of the DEGs were mainly enriched in glyoxylate and dicarboxylate metabolism (sot00630), nitrogen metabolism (sot00910), tryptophan metabolism (sot00380), and plant hormone signal transduction (sot04075), and these DEGs might be involved in the interactions between Bacillus megaterium P68 and potato growth. The qRT-PCR analysis of differentially expressed genes showed that inoculated treatments P68 significantly upregulated expression of the phosphate transport, nitrate transport, glutamine synthesis, and abscisic acid regulatory pathways, respectively, and the data from qRT-PCR were consistent with that obtained from RNA-seq. In summary, PSB may be involved in the regulation of nitrogen and phosphorus nutrition, glutaminase synthesis, and abscisic acid-related metabolic pathways. This research would provide a new perspective for studying the molecular mechanism of potato growth promotion by PSB in the level of gene expression and related metabolic pathways in potato roots under the application of Bacillus megaterium P68.

Comparative transcriptome analysis of purple-fleshed sweet potato and its yellow-fleshed mutant provides insight into the transcription factors involved in anthocyanin biosynthesis in tuberous root.

In various plant species, many transcription factors (TFs), such as MYB, bHLH, and WD40, have been identified as regulators of anthocyanin biosynthesis in underground organs. However, the regulatory elements of anthocyanin biosynthesis in the tuberous roots of sweet potato have not been elucidated yet. Here, we selected the purple-fleshed sweet potato cultivar "Zhezi1" (ZZ P ) and its spontaneous yellow-fleshed mutant "Xinli" (XL Y ) to investigate the regulatory mechanism of the anthocyanin biosynthesis in the tuberous roots of sweet potato. By analyzing the IbMYB1 genotype in ZZ P and XL Y , we found that the IbMYB1-2, a MYB TF involved in anthocyanin biosynthesis, was missing in the XL Y genome, which might lead to an extreme decrease in anthocyanins in XL Y . A comparative transcriptome analysis of ZZ P and XL Y was conducted to find the TFs involved in anthocyanin biosynthesis in ZZ P and XL Y . The anthocyanin structural genes were significantly enriched among the differentially expressed genes. Moreover, one MYB activator (IbMYB1), one bHLH (IbbHLH2), three WRKY activator candidates (IbWRKY21, IbWRKY24, and IbWRKY44), and two MYB repressors (IbMYB27 and IbMYBx-ZZ) were highly expressed in ZZ P accompanied with anthocyanin structural genes. We also tested the expression of these TFs in six purple- and two orange-fleshed sweet potato cultivars. Interestingly, most of these TFs were significantly positively correlated with anthocyanin contents in these cultivars. The function of the anthocyanin biosynthesis repression of IbMYB27 and IbMYBx-ZZ was verified through transient co-transformation with IbMYB1 into tobacco leaves. Further functional verification of the above TFs was conducted by Y2H, BiFC, and dual-luciferase assays. These tests showed that the MYB-bHLH-WD40/MYB-bHLH-WD40-WRKY complex activated the promoter of anthocyanin structural gene IbDFR and promoters for IbWRKY44, IbMYB27, and IbMYBx-ZZ, indicating reinforcement and feedback regulation to maintain the level of anthocyanin accumulation in the tuberous roots of purple-fleshed sweet potato. These results may provide new insights into the regulatory mechanism of anthocyanin biosynthesis and accumulation in underground organs of sweet potatoes.

Physiology and Gene Expression Analysis of Potato (Solanum tuberosum L.) in Salt Stress.

The production of potato (Solanum tuberosum L.) faces a severe challenge due to the salinization of arable land worldwide. The cultivation of salt-tolerant potatoes is of great significance to ensure food security. In this study, two cultivars of 'Longshu 5' and 'Qingshu 9' were compared for physiological responses to salt stress, and then the salt tolerance of the two cultivars were assessed via principal component analysis. Furthermore, the Na+, K+, and Ca2+ flux of the cultivars under salt stress was recorded. Finally, the expression levels of ion transport-related genes and transcription factors in salt-tolerant cultivars were explored under NaCl stress. The results showed that the seven physiological indicators of salt tolerance were differed between the cultivars. Interestingly, soluble protein and sugar were early responsive to salt stress than proline in the salt-tolerance cultivar. Peroxidase and superoxide dismutase activity were significantly different in 'Longshu 5' under NaCl stress and without being significantly different in 'Qingshu9'. In addition, the salt tolerance of 'Longshu 5' was more tolerant than 'Qingshu 9' based on principal component evaluation. Meanwhile, the strong efflux of Na+, the stability of K+, and the high absorption of Ca2+ in 'Longshu 5' indicated salt adaption mechanisms in the salt-tolerant potato. In addition, we found that ion transport-related genes and transcription factors, such as StSOS1, StNHX4, StAKT1, StNAC24, and StCYP707A, played a role in the salt tolerance of 'Longshu 5'. In conclusion, the salt-tolerant potato can regulate physiological substances to adapt to salt stress, and ion transport related genes and transcription factors play a role in improving salt tolerance.

Accuracy improvement in plastics classification by laser-induced breakdown spectroscopy based on a residual network.

The whole ecosystem is suffering from serious plastic pollution. Automatic and accurate classification is an essential process in plastic effective recycle. In this work, we proposed an accurate approach for plastics classification using a residual network based on laser-induced breakdown spectroscopy (LIBS). To increasing efficiency, the LIBS spectral data were compressed by peak searching algorithm based on continuous wavelet, then were transformed to characteristic images for training and validation of the residual network. Acrylonitrile butadiene styrene (ABS), polyamide (PA), polymethyl methacrylate (PMMA), and polyvinyl chloride (PVC) from 13 manufacturers were used. The accuracy of the proposed method in few-shot learning was evaluated. The results show that when the number of training image data was 1, the verification accuracy of classification by plastic type under residual network still kept 100%, which was much higher than conventional classification algorithms (BP, kNN and SVM). Furthermore, the training and testing data were separated from different manufacturers to evaluate the anti-interference properties of the proposed method from various additives in plastics, where 73.34% accuracy was obtained. To demonstrate the superiority of classification accuracy in the proposed method, all the evaluations were also implemented by using conventional classification algorithm (kNN, BP, SVM algorithm). The results confirmed that the residual network has a significantly higher accuracy in plastics classification and shows great potential in plastic recycle industries for pollution mitigation.

Transcriptome analysis uncovers the gene expression profile of salt-stressed potato (Solanum tuberosum L.).

Potato (Solanum tuberosum L.) is an important staple food worldwide. However, its growth has been heavily suppressed by salt stress. The molecular mechanisms of salt tolerance in potato remain unclear. It has been shown that the tetraploid potato Longshu No. 5 is a salt-tolerant genotype. Therefore, in this study we conducted research to identify salt stress response genes in Longshu No. 5 using a NaCl treatment and time-course RNA sequencing. The total number of differentially expressed genes (DEGs) in response to salt stress was 5508. Based on Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) analysis, it was found that DEGs were significantly enriched in the categories of nucleic acid binding, transporter activity, ion or molecule transport, ion binding, kinase activity and oxidative phosphorylation. Particularly, the significant differential expression of encoding ion transport signaling genes suggests that this signaling pathway plays a vital role in salt stress response in potato. Finally, the DEGs in the salt response pathway were verified by Quantitative real-time PCR (qRT-PCR). These results provide valuable information on the salt tolerance of molecular mechanisms in potatoes, and establish a basis for breeding salt-tolerant cultivars.

[Effects of organic solvents on proliferation of Hela cells line].

OBJECTIVE: To research the effects of organic solvents on proliferation inhibition of Hela cells line. METHODS: The apoptosis of Hela cells induced by ethanol and dimethylsulfoxide (DMSO) were studied to analyse the error analyse from background organic solvents. The apoptosis of Hela cells induced by ethanol, DMSO and the combination of these two organic solvents with different concentrations were observed by MTT test and Giemsa staining. RESULTS: The Hela cells proliferation were significantly inhibited by ethanol with the concentrations ranged from 30% to 100%, and DMSO with the concentrations ranged from 50% to 100% (P < 0.01). There were no significantly difference between the two combination of ethanol 40% + DMSO 60%, ethanol 30% + DMSO 70% and control group (P > 0. 05) respectively. CONCLUSION: The cells proliferation were inhibited by organic solvents itself and were in a time and dose dependent. The background experimental error can be reduced remarkably by choosing the two organic solvents combination of ethanol and DMSO.

Stress responsive gene CIPK14 is involved in phytochrome A-mediated far-red light inhibition of greening in Arabidopsis.

In this study, we show that CIPK14, a stress responsive CBL-interacting protein kinase gene, is involved in phytochrome A-mediated far-red light inhibition of greening in Arabidopsis seedlings. The CIPK14-impairment mutant cipk14 grown in continuous far-red (FR) light did not show greening when exposed to white light illumination for 15 h. By contrast, the FR-grown phytochrome A null mutant phyA greened within 0.5 h of exposure to white light. Although greening of Col-4 (wild-type) was not completely abolished by FR, it exhibited a significantly decreased greening capacity compared with that of phyA. Further analyses demonstrated that the expression of protochlorophyllide reductase (POR) genes was correlated with the greening ability of the genotypes. In addition, CIPK14 appeared to be regulated by both the circadian clock and PhyA. Taken together, these results suggest that CIPK14 plays a role in PhyA-mediated FR inhibition of seedling greening, and that a Ca-related kinase may be involved in a previously undefined branch point in the phytochrome A signaling pathway.

Regulation of salt and ABA responses by CIPK14, a calcium sensor interacting protein kinase in Arabidopsis.

Calcium and protein kinase serve as the common mediators to regulate plant responses to multiple stresses including salt and ABA stimulus. Here we reported a novel protein kinase (CIPK14) that regulated the responses to ABA treatment and salt stress in Arabidopsis. CIPK14 transcripts, capable been checked in roots, stems, leaves and flowers, were highly expressed in flowers and roots. CIPK14 was induced by ABA and salt treatments. The disruption of CIPK14 altered the transcriptional pattern of a gene marker line related to ABA and salt responses, and the results suggested that CIPK14 probably was responsible to the control of the salt and ABA responses. Comparing with wild types, the lines inserted with the T-DNA in which CIPK14 gene expression was knocked out were also more sensitive to ABA and salt stimulus, showing low germination rate and the less root elongation. While, when these conditioned seeds were treated with norflurazon, their germination percentages could recover to a certain extent. We also found that exogenous calcium could have an effect on the transcription of CIPK14 under ABA and salt treatments, and it seemed that calcium ion might work upstream CIPK14 to regulate the plant response to ABA and salt response.

A calcium-dependent protein kinase is involved in plant hormone signal transduction in Arabidopsis.

A number of signal pathways have been found through which abundant calcium-stimulated protein kinase activity in plant is associated with calcium-dependent protein kinases (CDPKs) which act as the calcium sensors mediating numerous responses, including hormone signaling. Basing on previous studies, we made additional functional analysis of the gene AtCPK30 encoding a protein kinase in Arabidopsis. Results of semi-quantitative reverse transcription PCR (RT-PCR) analysis indicated that AtCPK30 was highly expressed in root and induced by ABA, IAA, 2,4-D, GA(3) and 6-BA treatment. The physiological roles of AtCPK30 were studied using a gain-of-function approach. Seedlings of AtCPK30 transgenic lines had longer primary roots than those plants of wild-type at the early stages. Interestingly, when these plants grew on MS lack of Ca(2+) including wild-type and transgenic lines, the roots of transgenic line were more sensitive to calcium, lack of Ca(2+) had less effect on roots of transgenic lines than those of wild-type. Treated with several plant hormones, such as ABA, IAA, GA(3) and 6-BA, the roots of seedlings of transgenic line developed abnormally because they were more sensitive to hormones. Furthermore, NPA relatively less inhibited emergency of lateral roots of transgenic line than those of the wild-type. Green fluorescent protein-CPK30 (GFP-CPK30) fusion protein studies revealed the localization of AtCPK30 to both cell wall and plasma membrane. These results suggest that AtCPK30 acts as the calcium sensor and involved in the hormone-signaling pathways.