Abscisic-acid-responsive StlncRNA13558 induces StPRL expression to increase potato resistance to Phytophthora infestans infection.

Late blight, caused by Phytophthora infestans, is one of the most serious diseases affecting potatoes (Solanum tuberosum L.). Long non-coding RNAs (lncRNAs) are transcripts with a length of more than 200 nucleotides that have no protein-coding potential. Few studies have been conducted on lncRNAs related to plant immune regulation in plants, and the molecular mechanisms involved in this regulation require further investigation. We identified and screened an lncRNA that specifically responds to P. infestans infection, namely, StlncRNA13558. P. infestans infection activates the abscisic acid (ABA) pathway, and ABA induces StlncRNA13558 to enhance potato resistance to P. infestans. StlncRNA13558 positively regulates the expression of its co-expressed PR-related gene StPRL. StPRL promotes the accumulation of reactive oxygen species and transmits a resistance response by affecting the salicylic acid hormone pathway, thereby enhancing potato resistance to P. infestans. In summary, we identified the potato late blight resistance lncRNA StlncRNA13558 and revealed its upstream and downstream regulatory relationship of StlncRNA13558. These results improve our understanding of plant-pathogen interactions' immune mechanism and elucidate the response mechanism of lncRNA-target genes regulating potato resistance to P. infestans infection.

Efficient Nd:YAG crystal laser with rotatory pumping.

The performance of solid-state laser is limited by the thermal effects in the gain medium. In this study, we investigated the implementation of an efficient short-cavity continuous-wave 1064 nm Nd:YAG solid-state laser by using a rotatory pumping scheme to alleviate the thermal accumulation in the gain medium. With this method, the laser power reached 25.7 W with a slope efficiency of 41.5% at a 10.0-mm pump rotation radius and an optimum rotation rate of 2300 rpm. The influence of rotatory pumping radius and rotation rates was analyzed, and the results indicated that the rotatory pumping would be promising technique for the power scaling of solid-state lasers.

Potato (Solanum tuberosum L.) non-specific lipid transfer protein StLTP6 promotes viral infection by inhibiting virus-induced RNA silencing.

MAIN CONCLUSION: For the first time it is reported that members of the nsLTP protein family could promote viral infection by inhibiting virus-induced RNA silencing. Non-specific lipid transfer proteins (nsLTPs) are a class of soluble proteins with low relative molecular weight and widely present in higher plants. The role of nsLTPs in biotic and abiotic stresses has been studied, but no report has shown that nsLTPs play a role in the process of viral infection. We report the function and mechanism of the classical nsLTP protein StLTP6 in viral infection. We found that StLTP6 expression was remarkably upregulated in potato infected with potato virus Y and potato virus S. The infection efficiency and virus content of StLTP6-overexpressed potato and Nicotiana benthamiana were remarkable increased. Further study found that the overexpression of StLTP6 inhibited the expression of multiple genes in the RNA silencing pathway, thereby inhibiting virus-induced RNA silencing. This result indicated that StLTP6 expression was induced during viral infection to inhibit the resistance of virus-induced RNA silencing and promote viral infection. In summary, we reported the role of StLTP6 in viral infection, broadening the biological function range of the nsLTP family and providing valuable information for the study of viral infection mechanism.

Genome-Wide Identification and Characterization of Potato Long Non-coding RNAs Associated With Phytophthora infestans Resistance.

Long non-coding RNA (lncRNA) is a crucial regulatory mechanism in the plant response to biotic and abiotic stress. However, their roles in potato (Solanum tuberosum L.) resistance to Phytophthora infestans (P. infestans) largely remain unknown. In this study, we identify 2857 lncRNAs and 33,150 mRNAs of the potato from large-scale published RNA sequencing data. Characteristic analysis indicates a similar distribution pattern of lncRNAs and mRNAs on the potato chromosomes, and the mRNAs were longer and had more exons than lncRNAs. Identification of alternative splicing (AS) shows that there were a total of 2491 lncRNAs generated from AS and the highest frequency (46.49%) of alternative acceptors (AA). We performed R package TCseq to cluster 133 specific differentially expressed lncRNAs from resistance lines and found that the lncRNAs of cluster 2 were upregulated. The lncRNA targets were subject to KEGG pathway enrichment analysis, and the interactive network between lncRNAs and mRNAs was constructed by using GENIE3, a random forest machine learning algorithm. Transient overexpression of StLNC0004 in Nicotiana benthamiana significantly suppresses P. infestans growth compared with a control, and the expression of extensin (NbEXT), the ortholog of the StLNC0004 target gene, was significantly upregulated in the overexpression line. Together, these results suggest that lncRNAs play potential functional roles in the potato response to P. infestans infection.

A nonspecific lipid transfer protein, StLTP10, mediates resistance to Phytophthora infestans in potato.

Nonspecific lipidtransfer proteins (nsLTPs), which are small, cysteine-rich proteins, belong to the pathogenesis-related protein family, and several of them act as positive regulators during plant disease resistance. However, the underlying molecular mechanisms of these proteins in plant immune responses are unclear. In this study, a typical nsLTP gene, StLTP10, was identified and functionally analysed in potato. StLTP10 expression was significantly induced by Phytophthora infestans, which causes late blight in potato, and defence-related phytohormones, including abscisic acid (ABA), salicylic acid, and jasmonic acid. Characterization of StLTP10-overexpressing and knockdown lines indicated that StLTP10 positively regulates plant resistance to P. infestans. This resistance was coupled with enhanced expression of reactive oxygen species scavenging- and defence-related genes. Furthermore, we identified that StLTP10 physically interacts with ABA receptor PYL4 and affects its subcellular localization. These two proteins work together to regulate stomatal closure during pathogen infection. Interestingly, we also found that wound-induced protein kinase interacts with StLTP10 and positively regulates its protein abundance. Taken together, our results provide insight into the role of StLTP10 in resistance to P. infestans and suggest candidates to enhance broad-spectrum resistance to pathogens in potato.

Global transcriptome analyses reveal the molecular signatures in the early response of potato (Solanum tuberosum L.) to Phytophthora infestans, Ralstonia solanacearum, and Potato virus Y infection.

MAIN CONCLUSION: Specific and common genes including transcription factors, resistance genes and pathways were significantly induced in potato by Phytophthora infestans, Ralstonia solanacearum, and Potato virus Y infection. The three major pathogens, namely, Phytophthora infestans, Ralstonia solanacearum, and Potato virus Y, can cause late blight, bacterial wilt, and necrotic ringspot, respectively, and thus severely reduce the yield and quality of potatoes (Solanum tuberosum L.). This study was the first to systematically analyze the relationship between transcriptome alterations in potato infected by these pathogens at the early stages. A total of 75,500 unigenes were identified, and 44,008 were annotated into 5 databases, namely, non-redundant (NR), Swiss-Prot protein, clusters of orthologous groups for eukaryotic complete genomes (KOG), Gene Ontology (GO), and Kyoto Encyclopedia of Genes and Genomes (KEGG) databases. A total of 6945 resistance genes and 11,878 transcription factors (TFs) were identified from all transcriptome data. Differential expression analysis revealed that 13,032 (9490 specifics), 9877 (6423 specifics), and 6661 (4144 specifics) differentially expressed genes (DEGs) were generated from comparisons of the P. infestans/control (Pi vs. Pi-CK), R. solanacearum/control (Rs vs. Rs-CK), and PVY/control (PVY vs. PVY-CK) treatments, respectively. The specific DEGs from the 3 comparisons were assigned to 13 common pathways, such as biosynthesis of amino acids, plant hormone signal transduction, carbon metabolism, and starch and sucrose metabolism. Weighted Gene Co-Expression Network Analysis (WGCNA) identified many hub unigenes, of which several unigenes were reported to regulate plant immune responses, such as FLAGELLIN-SENSITIVE 2 and chitinases. The present study provide crucial systems-level insights into the relationship between transcriptome changes in potato infected with the three pathogens. Moreover, this study presents a theoretical basis for breeding broad-spectrum and specific pathogen-resistant cultivars.

Transgenic RXLR Effector PITG_15718.2 Suppresses Immunity and Reduces Vegetative Growth in Potato.

Phytophthora infestans causes the severe late blight disease of potato. During its infection process, P. infestans delivers hundreds of RXLR (Arg-x-Leu-Arg, x behalf of any one amino acid) effectors to manipulate processes in its hosts, creating a suitable environment for invasion and proliferation. Several effectors interact with host proteins to suppress host immunity and inhibit plant growth. However, little is known about how P. infestans regulates the host transcriptome. Here, we identified an RXLR effector, PITG_15718.2, which is upregulated and maintains a high expression level throughout the infection. Stable transgenic potato (Solanum tuberosum) lines expressing PITG_15718.2 show enhanced leaf colonization by P. infestans and reduced vegetative growth. We further investigated the transcriptional changes between three PITG_15718.2 transgenic lines and the wild type Désirée by using RNA sequencing (RNA-Seq). Compared with Désirée, 190 differentially expressed genes (DEGs) were identified, including 158 upregulated genes and 32 downregulated genes in PITG_15718.2 transgenic lines. Eight upregulated and nine downregulated DEGs were validated by real-time RT-PCR, which showed a high correlation with the expression level identified by RNA-Seq. These DEGs will help to explore the mechanism of PITG_15718.2-mediated immunity and growth inhibition in the future.

Analysis of TDMP Algorithm of LDPC Codes Based on Density Evolution and Gaussian Approximation.

Based on density evolution analysis of the existing belief propagation (BP) algorithm, the Turbo Decoding Message Passing (TDMP) algorithm was analyzed from the perspective of density evolution and Gaussian approximation, and the theoretical analysis process of TDMP algorithm was given. When calculating the prior message of each layer of the TDMP algorithm, the check message of the previous iteration should be subtracted. Therefore, the result will not be convergent, if the TDMP algorithm is directly analyzed based on density evolution and Gaussian approximation. We researched the TDMP algorithm based on the symmetry conditions to obtain the convergent result. When using density evolution (DE) and Gaussian approximation to analyze the decoding convergence of the TDMP algorithm, we can provide a theoretical basis for proving the superiority of the algorithm. Then, based on the DE theory, we calculated the probability density function (PDF) of the check-to-variable information of TDMP and its simplified algorithm, and then gave it a calculation based on the process of the normalization factor. Simulation results show that the decoding convergence speed of the TDMP algorithm was faster and the iterations were smaller compared to the BP algorithm under the same conditions.

High-degree and broad-spectrum resistance mediated by a combination of NIb siRNA and miRNA suppresses replication of necrotic and common strains of potato virus Y.

In plants, viral replication can be inhibited through gene silencing, which is mediated by short interfering RNA (siRNA) or microRNA (miRNA). However, under natural conditions, viruses are extremely susceptible to mutations that may decrease the efficiency of cleavage of these small RNAs (sRNAs). Therefore, a single sRNA may not provide a sufficient degree of viral resistance to transgenic plants. Potato virus Y necrotic strain (PVYN) and Potato virus Y common strain (PVYO) are the two major PVY strains that cause systemic necrosis and mottling, respectively, in tobacco. In this study, we designed specific siRNAs and miRNAs to target two regions of the PVYO replicase gene (NIb). Eight plant expression vectors containing one or two sRNAs were constructed. Luciferase activity assays showed that the designed sRNAs successfully cleaved the NIb gene of PVYO and PVYN, and the vector carrying a combined siRNA- and miRNA-based short hairpin RNA (shRNA) demonstrated the strongest inhibitory effect. These effects were confirmed through the acquisition of PVYO and PVYN resistance in transgenic sRNA-expressing Nicotiana tabacum plants. This phenomenon could be related to a plant defense mechanism in which siRNA and miRNA pathways are complementary and interact to achieve gene silencing. Furthermore, there is a tendency for the homologous small RNA sequences (PVYO) to be more effective in conferring resistance than those with imperfect homology (PVYN). Overall, these findings confirm that the use of a combined siRNA- and miRNA-based shRNAs is a promising approach for introducing viral resistance to plants through genetic engineering.