Devosia lacusdianchii sp. nov., an attached bacterium inhibited by metabolites from its symbiotic Microcystis.

A novel alphaproteobacterial strain JXJ CY 41T was isolated from a culture mass of Microcystis, collected from Lake Dianchi, south-west, China. Strain JXJ CY 41T was gram-strain-negative, aerobic, motile, with rod-shaped cells (0.4-1.0 × 1.7-3.5 µm). It was positive for catalase and starch hydrolysis, negative for oxidase and hydrolysis of Tweens (20, 40, and 80). Growth occurred at 10-44 °C, pH 5.0-10.0, and 0-5.0% (w/v) NaCl. Major fatty acids included C16:0 (28.1%), 11-methyl C18:1 ω7c (36.7%) and C18:1 ω7c (20.8%). Q10 was the sole ubiquinone. The polar lipids were diphosphatidylglycerol, phosphatidylglycerol, glycolipid, and an unidentified lipid. The DNA G + C content was 63.1%. Its 16S rRNA gene sequence showed high similarities with Devosia oryziradicis G19T (99.5%; not validly published), D. yakushimensis Yak96BT (98.3%) and D. ginsengisoli Gsoil 520T (98.1%), and less than 98.1% similarities with other members of the genus Devosia. The digital DNA-DNA hybridization (dDDH) and average nucleotide identity (ANI) values between strain JXJ CY 41T and its 5 closest similar strains were 19.9-24.1% and 75.7-80.5%, respectively. Based on the data above, strain JXJ CY 41T was identified as a novel species of the genus Devosia, for which the epithet Devosia lacusdianchii sp. nov. was proposed. The type strain is JXJ CY 41T (= KCTC 72812T = CGMCC 1.17502T). Strain JXJ CY 41T exhibited different interactions with Microcystis aeruginosa FACHB-905 (Maf) under different conditions, and Maf could control the bacterial cellular density by secreting unknown specific chemical compounds according to its nutritional requirements.

Identification and fine-mapping of Xo2, a novel rice bacterial leaf streak resistance gene.

KEY MESSAGE: A novel rice resistance gene, Xo2, influencing pathogenesis of the bacterial leaf streak disease, has been identified, and candidate genes for Xo2 in the fine mapping region have been shown to be involved in bacterial leaf streak resistance. Rice (Oryza sativa) bacterial leaf streak, caused by Xanthomonas oryzae pv. oryzicola (Xoc), is one of the most serious rice bacterial diseases. The deployment of host resistance genes is an effective approach for controlling this disease. The cultivar BHADOIA 303 (X455) from Bangladesh is resistant to most of Chinese Xoc races. To identify and map the resistance gene(s) involved in Xoc resistance, we examined the association between phenotypic and genotypic variations in two F2 populations derived from crosses between X455/Jingang 30 and X455/Wushansimiao. The segregation ratios of the F2 progeny were consistent with the action of a single dominant resistance gene, which was designated as Xo2. Based on rice SNP chip (GSR40K) assays of X455, Jingang 30, and resistant and susceptible pools thereof, we mapped Xo2 to the region from 10 Mb to 12.5 Mb on chromosome 2. The target gene was further finely mapped between the markers RM12941 and D6-1 within an approximately 110-kb region. The de novo sequencing and gene annotation of X455 and Jingang 30 revealed nineteen predicted genes within the target region. RNA-seq and expression analysis showed that four candidate genes, including Osa002T0115800, encoding an NLR resistance protein, were distinctly upregulated. Differential sequence and synteny analysis between X455 and Jingang 30 suggested that Osa002T0115800 is likely the functional Xo2 gene. This study lays a foundation for marker-assisted selection resistance breeding against rice bacterial leaf streak and the further cloning of Xo2.

Overexpression of OsGF14f Enhances Quantitative Leaf Blast and Bacterial Blight Resistance in Rice.

Although it is known that rice 14-3-3 family genes are involved in various defense responses, the functions of OsGF14f in response to diseases have not been reported. Here, we showed that the transcription of OsGF14f was significantly induced by leaf blast infection, and the overexpression of OsGF14f quantitatively enhanced resistance to leaf blast and bacterial blight in rice. Further analysis showed that the expression levels of salicylic acid (SA) pathway-associated genes (PAL1, NH1, PR1a and PR10) in the OsGF14f-overexpressing plants, were higher than those in wild-type plants after inoculation with the blast isolate (Magnaporthe oryzae Barr). In addition, the expression level of OsGF14f was significantly induced after SA treatment, and higher endogenous SA levels were observed in the OsGF14f-overexpressing plants compared with that in wild-type plants, especially after blast challenge. Taken together, these results suggest that OsGF14f positively regulates leaf blast and bacterial blight resistance in rice via the SA-dependent signaling pathway.

Dynamics of the Rice Blast Fungal Population in the Field After Deployment of an Improved Rice Variety Containing Known Resistance Genes.

Rice blast, caused by the fungus Magnaporthe oryzae, is one of the most destructive diseases of rice worldwide. Management through the deployment of host resistance genes would be facilitated by understanding the dynamics of the pathogen's population in the field. Here, to investigate the mechanism underlying the breakdown of disease resistance, we conducted a six-year field experiment to monitor the evolution of M. oryzae populations in Qujiang from Guangdong. The new variety of Xin-Yin-Zhan (XYZ) carrying R genes Pi50 and Pib was developed using the susceptible elite variety, Ma-Ba-Yin-Zhan (MBYZ), as the recurrent line. Field trials of disease resistance assessment revealed that the disease indices of XYZ in 2012, 2013, 2016, and 2017 were 0.19, 0.39, 0.70, and 0.90, respectively, indicating that XYZ displayed a very rapid increase of disease severity in the field. To investigate the mechanism underlying the quick erosion of resistance of XYZ, we collected isolates from both XYZ and MBYZ for pathogenicity testing against six different isogenic lines. The isolates collected from XYZ showed a similar virulence spectrum across four different years whereas those from MBYZ showed increasing virulence to the Pi50 and Pib isogenic lines from 2012 to 2017. Molecular analysis of AvrPib in the isolates from MBYZ identified four different AvrPib haplotypes, i.e., AvrPib-AP1-1, AvrPib-AP1-2, avrPib-AP2, and avrPib-AP3, verified by sequencing. AvrPib-AP1-1 and AvrPib-AP1-2 are avirulent to Pib whereas avrPib-AP2 and avrPib-AP3 are virulent. Insertions of a Pot3 and an Mg-SINE were identified in avrPib-AP2 and avrPib-AP3, respectively. Two major lineages based on rep-PCR analysis were further deduced in the field population, implying that the field population is composed of genetically related isolates. Our data suggest that clonal propagation and quick dominance of virulent isolates against the previously resistant variety could be the major genetic events contributing to the loss of varietal resistance against rice blast in the field.

Orbitides isolated from flaxseed induce apoptosis against SGC-7901 adenocarcinoma cells.

Unique plant-derived cyclic peptides family exhibiting various key biological activities has great possibility for anticancer therapy. In this study, we investigated the effects of orbitides isolated from flax (Linum usitatissimum L.) on the growth of SGC-7901 cancer cells and the potential mechanism. Results showed that flaxseed orbitides killed off cancer cells by inducing apoptosis in a dose-dependent manner, which was confirmed by the appearance of nuclear shrinkage and DNA fragmentation, and the inhibitory effect was stronger than that of pure orbitide [1-9-NαC]-linusorb B2 or [1-9-NαC]-linusorb B3. Besides, the mitochondrial apoptosis pathway-related protein cytochrome C (Cyt C) was released from mitochondria to cytosol, associated with the activation of caspases 9 and 3, and the cleavage of PARP. Taken together, these results indicated that flaxseed orbitides induced apoptosis via the mitochondrial pathway, releasing Cyt C, increasing Bax/Bcl-2 ratio and elevating the expression of cleaved caspase 9 and 3 in SGC-7901 cells.

Dynamic Insertion of Pot3 in AvrPib Prevailing in a Field Rice Blast Population in the Philippines Led to the High Virulence Frequency Against the Resistance Gene Pib in Rice.

The Magnaporthe oryzae avirulence gene AvrPib is required for the resistance mediated by its cognate resistance gene Pib, which has been intensively used in indica rice breeding programs in many Asian countries. However, the sequence diversity of AvrPib among geographically distinct M. oryzae populations was recently shown to be increasing. Here, we selected a field population consisting of 248 rice blast isolates collected from a disease hotspot in Philippine for the analysis of AvrPib haplotypes and their pathogenicity against Pib. We found that all of the isolates were virulent to Pib and each of them contained an insertion of Pot3 transposon in AvrPib. Moreover, Pot3 insertion was detected in different genomic positions, resulting in three different AvrPib haplotypes, designated avrPib-H1 to H3. We further conducted a genome-wide Pot2 fingerprinting analysis by repetitive element palindromic polymerase chain reaction (PCR) and identified seven different lineages out of 47 representative isolates. The isolates belonging to the same lineage often had the same AvrPib haplotype. In contrast, the isolates having the same AvrPib haplotypes did not always belong to the same lineages. Both mating types MAT1-1 and MAT1-2 were identified in the population in Bohol and the latter appeared dominant. On the host side, we found that 32 of 52 released rice varieties in the Philippines contained Pib diagnosed by PCR gene-specific primers and DNA sequencing of gene amplicons, suggesting that it was widely incorporated in different rice varieties. Our study highlights the genetic dynamics of rice blast population at both the AvrPib locus and the genome-wide levels, providing insight into the mechanisms of the mutations in AvrPib leading to the breakdown of Pib-mediated resistance in rice.

NAC transcription factor ONAC066 positively regulates disease resistance by suppressing the ABA signaling pathway in rice.

KEY MESSAGE: This is the first time to dissect the mechanism of NACs-mediated disease resistance in plants using metabolomic approach and discover the involvement of ABA signaling pathway in NACs-mediated disease resistance. NAC transcription factors have been validated as important regulators in stress responses, but their molecular mechanisms in plant disease resistance are still largely unknown. Here we report that the NAC gene ONAC066 (LOC_Os01g09550) is significantly activated by rice blast infection. ONAC066 is ubiquitously expressed and this protein is localized in the nucleus. Overexpression of ONAC066 quantitatively enhances resistance to blast disease and bacterial blight in rice. The transcript levels of PR genes are also dramatically induced in ONAC066 overexpressing plants. Exogenous abscisic acid (ABA) strongly activates the transcription of ONAC066 in rice. Further analysis shows that overexpression of ONAC066 remarkably suppresses the expression of ABA-related genes, whereas there are no obvious differences for salicylic acid (SA) and jasmonic acid (JA)-related genes between wild-type and ONAC066 overexpressing plants. Consistently, lower endogenous ABA levels are identified in ONAC066 overexpressing plants compared with wild-type plants before and after blast inoculation, while no significant differences are observed for the SA and JA levels. Yeast one-hybrid assays demonstrate that ONAC066 directly binds to the promoters of LIP9 and NCED4 to modulate their expression. Moreover, the metabolomic study reveals that the ONAC066 overexpressing plants accumulated higher contents of soluble sugars and amino acids both before and after pathogen attack, when compared to wild-type plants. Taken together, our results suggest that ONAC066 positively regulates rice resistance to blast and bacterial blight, and ONAC066 exerts its functions on disease resistance by modulating of ABA signaling pathway, sugars and amino acids accumulation in rice.

OsWRKY67 positively regulates blast and bacteria blight resistance by direct activation of PR genes in rice.

BACKGROUND: WRKY proteins are one of the largest gene families and are well-known for their regulatory roles in many aspects of plant development, including plant response to both biotic and abiotic stresses. Although the roles of WRKY proteins in leaf blast resistance have been well-documented in rice, their functions in panicle blast, the most destructive type of blast disease, are still largely unknown. RESULTS: Here, we identified that the transcription of OsWRKY67 was strongly activated by leaf and panicle blast infection. OsWRKY67 is ubiquitously expressed and sub-localized in the nucleus. Rice plants overexpressing OsWRKY67 showed quantitatively enhanced resistance to leaf blast, panicle blast and bacterial blight. In contrast, silencing of OsWRKY67 increased the susceptibility to blast and bacterial blight diseases. RNA-seq analysis indicated that OsWRKY67 induces the transcription of a set of defense-related genes including the ones involved in the salicylic acid (SA)-dependent pathway. Consistent with this, the OsWRKY67-overexpressing plants accumulated higher amounts of endogenous SA, whereas lower endogenous SA levels were observed in OsWRKY67-silenced plants relative to wild-type Nipponbare plants before and after pathogen attack. Moreover, we also observed that OsWRKY67 directly binds to the promoters of PR1a and PR10 to activate their expression. CONCLUSIONS: These results together suggest the positive role of OsWRKY67 in regulating rice responses to leaf blast, panicle blast and bacterial blight disease. Furthermore, conferring resistance to two major diseases makes it a good target of molecular breeding for crop improvement in rice.

OsGF14b Positively Regulates Panicle Blast Resistance but Negatively Regulates Leaf Blast Resistance in Rice.

Although 14-3-3 proteins have been reported to be involved in responses to biotic stresses in plants, their functions in rice blast, the most destructive disease in rice, are largely unknown. Only GF14e has been confirmed to negatively regulate leaf blast. We report that GF14b is highly expressed in seedlings and panicles during blast infection. Rice plants overexpressing GF14b show enhanced resistance to panicle blast but are susceptible to leaf blast. In contrast, GF14b-silenced plants show increased susceptibility to panicle blast but enhanced resistance to leaf blast. Yeast one-hybrid assays demonstrate that WRKY71 binds to the promoter of GF14b and modulates its expression. Overexpression of GF14b induces expression of jasmonic acid (JA) synthesis-related genes but suppresses expression of salicylic acid (SA) synthesis-related genes. In contrast, suppressed GF14b expression causes decreased expression of JA synthesis-related genes but activation of SA synthesis-related genes. These results suggest that GF14b positively regulates panicle blast resistance but negatively regulates leaf blast resistance, and that GF14b-mediated disease resistance is associated with the JA- and SA-dependent pathway. The different functions for 14-3-3 proteins in leaf and panicle blast provide new evidence that leaf and panicle blast resistance are controlled by different mechanisms.

The germin-like protein OsGLP2-1 enhances resistance to fungal blast and bacterial blight in rice.

KEY MESSAGE: This is the first report that GLP gene (OsGLP2-1) is involved in panicle blast and bacterial blight resistance in rice. In addition to its resistance to blast and bacterial blight, OsGLP2-1 has also been reported to co-localize with a QTLs for sheath blight resistance in rice. These suggest that the disease resistance provided by OsGLP2-1 is quantitative and broad spectrum. Its good resistance to these major diseases in rice makes it to be a promising target in rice breeding. Rice (Oryza sativa) blast caused by Magnaporthe oryzae and bacterial blight caused by Xanthomonas oryzae pv. oryzae are the two most destructive rice diseases worldwide. Germin-like protein (GLP) gene family is one of the important defense gene families which have been reported to be involved in disease resistance in plants. Although GLP proteins have been demonstrated to positively regulate leaf blast resistance in rice, their involvement in resistance to panicle blast and bacterial blight, has not been reported. In this study, we reported that one of the rice GLP genes, OsGLP2-1, was significantly induced by blast fungus. Overexpression of OsGLP2-1 quantitatively enhanced resistance to leaf blast, panicle blast and bacterial blight. The temporal and spatial expression analysis revealed that OsGLP2-1is highly expressed in leaves and panicles and sub-localized in the cell wall. Compared with empty vector transformed (control) plants, the OsGLP2-1 overexpressing plants exhibited higher levels of H2O2 both before and after pathogen inoculation. Moreover, OsGLP2-1 was significantly induced by jasmonic acid (JA). Overexpression of OsGLP2-1 induced three well-characterized defense-related genes which are associated in JA-dependent pathway after pathogen infection. Higher endogenous level of JA was also identified in OsGLP2-1 overexpressing plants than in control plants both before and after pathogen inoculation. Together, these results suggest that OsGLP2-1 functions as a positive regulator to modulate disease resistance. Its good quantitative resistance to the two major diseases in rice makes it to be a promising target in rice breeding.

OsGF14e positively regulates panicle blast resistance in rice.

Though GF14e has been reported to negatively regulate bacterial blight and sheath blight resistance in rice, its effect on panicle blast, the most destructive disease in rice is still unknown. In the present study, we identified that GF14e was highly expressed in panicles and was induced in panicles infected by blast pathogen. Overexpression of GF14e enhances resistance to panicle blast whereas silencing GF14e results in increased susceptibility to panicle blast, suggesting that GF14e plays a positive role in quantitative panicle blast resistance in rice. Our results also demonstrate that GF14e is regulated by WRKY71 and GF14e-mediated panicle blast resistance is related to activation of SA-dependent pathway and suppression of JA-dependent pathway. The functional confirmation of GF14e in panicle blast resistance makes it to be a promising target in molecular rice breeding.

Algicidal Activity of Streptomyces eurocidicus JXJ-0089 Metabolites and Their Effects on Microcystis Physiology.

UNLABELLED: Copper sulfate (CuSO4) has been widely used as an algicide to control harmful cyanobacterial blooms (CyanoHABs) in freshwater lakes. However, there are increasing concerns about this application, due mainly to the general toxicity of CuSO4 to other aquatic species and its long-term persistence in the environment. This study reported the isolation and characterization of two natural algicidal compounds, i.e., tryptamine and tryptoline, from Streptomyces eurocidicus JXJ-0089. At a concentration of 5 µg/ml, both compounds showed higher algicidal efficiencies than CuSO4 on Microcystis sp. FACHB-905 and some other harmful cyanobacterial strains. Tryptamine and tryptoline treatments induced a degradation of chlorophyll and cell walls of cyanobacteria. These two compounds also significantly increased the intracellular oxidant content, i.e., superoxide anion radical (O2 (-)) and malondialdehyde (MDA), but reduced the activity of intracellular reductants, i.e., superoxide dismutase (SOD), of cyanobacteria. Moreover, tryptamine and tryptoline treatments significantly altered the internal and external contents of microcystin-LR (MC-LR), a common cyanotoxin. Like CuSO4, tryptamine and tryptoline led to releases of intracellular MC-LR from Microcystis, but with lower rates than CuSO4 Tryptamine and tryptoline (5 µg/ml) in cyanobacterial cultures were completely degraded within 8 days, while CuSO4 persisted for months. Overall, our results suggest that tryptamine and tryptoline could potentially serve as more efficient and environmentally friendly alternative algicides than CuSO4 in controlling harmful cyanobacterial blooms. IMPORTANCE: Cyanobacterial harmful algal blooms (CyanoHABs) in aquatic environments have become a worldwide problem. Numerous efforts have been made to seek means to prevent, control, and mitigate CyanoHABs. Copper sulfate (CuSO4), was once a common algicide to treat and control CyanoHABs. However, its application has become limited due to concerns about its general toxicity to other aquatic species and its long-term persistence in the environment. There is a great need for algicides with higher specificity and low environmental impacts. This study reports the isolation and characterization of two natural algicidal compounds from a streptomycete strain, Streptomyces eurocidicus JXJ-0089. Our results suggest that the identified algicides could potentially serve as more efficient and environmentally friendly alternative algicides than CuSO4 in controlling harmful cyanobacterial blooms.

L-valine, an antialgal amino acid from Streptomyces jiujiangensis JXJ 0074(T).

An antialgal compound was isolated from the cultured broth of Streptomyces jiujiangensis JXJ 0074(T) by using bioassay methods. Based on the data of (1)H-NMR, (13)C-NMR, ESI-MS, and thin layer chromatography, the active compound was identified as L-valine, which showed antialgal activity mainly against Microcystis. L-valine exhibited greater antialgal activities than both L-lysine and copper sulfate (CuSO4) did on Microcystis aeruginosa lawn. However, M. aeruginosa recovered growth earlier with higher growth rate in L-valine treatment than in L-lysine treatment. L-valine dissipated completely within 2 days, much quicker than L-lysine (6 days), which resulted in the lysing of more than 80 % M. aeruginosa cells and the release of amount of intracellular microcystin-LR (MC-LR) within 2 days. As a resultant, the extracellular MC-LR content was more than twice of the control from day 1 to 5. Exposure to L-valine significantly promoted the synthesis of MC-LR. L-lysine also promoted the release and synthesis of MC-LR with much lesser efficiency than L-valine. L-valine could damage Microcystis severely, causing perforation and collapse of M. aeruginosa cells and decrease of the chlorophyll. The superoxide dismutase (SOD) activity in L-valine-treated cells of M. aeruginosa initially increased with 32.94 ± 3.37 % higher than the control after 36 h and then decreased quickly. However, the increase rate of superoxide anion radical (O2 (-)) was much higher than that of SOD, which resulted in serious lipid peroxidation and accumulation of malondialdehyde (MDA). To our knowledge, this is the first report showing L-valine active against cyanobacteria.

Citricoccus lacusdiani sp. nov., an actinobacterium promoting Microcystis growth with limited soluble phosphorus.

A novel actinobacterium, designated strain JXJ CY 21T, was isolated from the culture mass of Microcystis sp. FACHB-905 collected from Lake Dianchi, South-west China. Polyphasic taxonomic study revealed that the isolate should be a member of the genus Citricoccus. Comparison of the 16S rRNA gene sequence of strain JXJ CY 21T with the available sequences in the GenBank database showed that the strain is closely related to Citricoccus zhacaiensis FS24T (97.8 % similarity), Citricoccus parietis 02-Je-010T (97.7 %), Citricoccus terreus V3M1T (97.6 %), Citricoccus nitrophenolicus PNP1T (97.2 %), Citricoccus alkalitolerans YIM 70010T (97.2 %) and Citricoccus muralis 4-0T (97.0 %). The DNA-DNA hybridization values between strain JXJ CY 21T and the related type strains C. zhacaiensis FS24T and C. parietis 02-Je-010T were 16.0 ± 2.6 and 5.4 ± 1.7 %, respectively. The peptidoglycan in the cell wall was A4α type containing lysine-glutamic acid-glycine. The major respiratory menaquinone was found to be MK-8 (H2) (98.5 %), while the major cellular fatty acids (>10 %) were anteiso-C15:0, iso-C16:0, iso-C15:0 and iso-C14:0. The polar lipids detected were diphosphatidylglycerol, phosphatidylinositol, phosphatidylglycerol, an unidentified phospholipid and an unidentified glycolipid. The DNA G + C content was determined to be 62.7 mol%. Strain JXJ CY 21T can solubilize both insoluble inorganic and organic phosphates up to 24.7 and 1.7 mg/l respectively. This property of the novel actinobacterium acts as a modulator for enhancement of growth of Microcystis sp. FACHB-905 in the lake ecosystem where the amount of soluble phosphate is limited. On the basis of the above taxonomic data, strain JXJ CY 21T represents a novel species of the genus Citricoccus, for which the name Citricoccus lacusdiani sp. nov. is proposed. The type strain is JXJ CY 21T (=KCTC 29653T = DSM 29160T).

Functional divergence of duplicated genes results in a novel blast resistance gene Pi50 at the Pi2/9 locus.

KEY MESSAGE: We characterized a novel blast resistance gene Pi50 at the Pi2/9 locus; Pi50 is derived from functional divergence of duplicated genes. The unique features of Pi50 should facilitate its use in rice breeding and improve our understanding of the evolution of resistance specificities. Rice blast disease, caused by the fungal pathogen Magnaporthe oryzae, poses constant, major threats to stable rice production worldwide. The deployment of broad-spectrum resistance (R) genes provides the most effective and economical means for disease control. In this study, we characterize the broad-spectrum R gene Pi50 at the Pi2/9 locus, which is embedded within a tandem cluster of 12 genes encoding proteins with nucleotide-binding site and leucine-rich repeat (NBS-LRR) domains. In contrast with other Pi2/9 locus, the Pi50 cluster contains four duplicated genes (Pi50_NBS4_1 to 4) with extremely high nucleotide sequence similarity. Moreover, these duplicated genes encode two kinds of proteins (Pi50_NBS4_1/2 and Pi50_NBS4_3/4) that differ by four amino acids. Complementation tests and resistance spectrum analyses revealed that Pi50_NBS4_1/2, not Pi50_NBS4_3/4, control the novel resistance specificity as observed in the Pi50 near isogenic line, NIL-e1. Pi50 shares greater than 96 % amino acid sequence identity with each of three other R proteins, i.e., Pi9, Piz-t, and Pi2, and has amino acid changes predominantly within the LRR region. The identification of Pi50 with its novel resistance specificity will facilitate the dissection of mechanisms behind the divergence and evolution of different resistance specificities at the Pi2/9 locus.

Streptomyces jiujiangensis sp. nov., isolated from soil in South China.

An actinomycete capable of lysing cyanobacteria, strain JXJ 0074(T), was isolated from a soil sample collected from Jiangxi province, south China, and characterized by using polyphasic taxonomy. The new isolate showed morphological and chemotaxonomic properties typical of members of the genus Streptomyces. Phylogenetic analysis of the near-complete 16S rRNA gene sequence indicated that strain JXJ 0074(T) should be affiliated to the genus Streptomyces and exhibited highest similarities to Streptomyces shenzhenensis DSM 42034(T) (98.99 %) and Streptomyces lucensis NBRC 13056(T) (98.60 %), while the similarities to other members of the genus are lower than 98.22 % similarity. However, the DNA-DNA hybridization values between strain JXJ 0074(T) and S. shenzhenensis DSM 42034(T) or S. lucensis NBRC 13056(T) were 46.2 ± 2.6 and 32.6 ± 3.1 %, respectively. Thus, on the basis of the polyphasic data, strain JXJ 0074(T) represents a novel species of the genus Streptomyces, for which the name Streptomyces jiujiangensis sp. nov. is proposed. The type strain is JXJ 0074(T) (= BCRC 16953(T) = KCTC 29262(T)).

Bacillus amyloliquefaciens LM-1 Affects Multiple Cell Biological Processes in Magnaporthe oryzae to Suppress Rice Blast.

Magnaporthe oryzae, one of the most destructive rice pathogens, causes significant losses during the rice harvest every year. Bacillus amyloliquefaciens has been explored in many crops as a potential biocontrol agent. However, the mechanisms of B. amyloliquefaciens controled rice blast are not fully understood. Here, a biocontrol strain LM-1, isolated from a contaminated medium, was identified as B. amyloliquefaciens using morphological observation, physiological and biochemical tests, and 16S rDNA sequencing. LM-1 inhibited the growth and pathogenicity of M. oryzae and Bipolaris oryzae (Breda de Haan) Shoem. The mycelia of M. oryzae co-cultured with LM-1 were enlarged and broken by fluorescence microscopy using calcofluor white. LM-1 inhibited the mycelia of M. oryzae from producing conidia. Genes itu, srf, and fenB were detected in LM-1. Furthermore, the supernatant of LM-1 interfered with the appressorium formation of M. oryzae, blocked conidial cell death, and reduced autophagy degradation but did not affect the normal germination of rice seeds and seeding growth. Additionally, we observed hypersensitivity reactions, reactive oxygen species, and iron accumulation reduction in rice cells inoculated with supernatant. Our study reveals that LM-1 has a control effect on rice blast and affects cell wall integrity, sporulation, appressorium formation, cell death, and autophagy.

Pangenome-Wide Association Study and Transcriptome Analysis Reveal a Novel QTL and Candidate Genes Controlling both Panicle and Leaf Blast Resistance in Rice.

Cultivating rice varieties with robust blast resistance is the most effective and economical way to manage the rice blast disease. However, rice blast disease comprises leaf and panicle blast, which are different in terms of resistance mechanisms. While many blast resistant rice cultivars were bred using genes conferring resistance to only leaf or panicle blast, mining durable and effective quantitative trait loci (QTLs) for both panicle and leaf blast resistance is of paramount importance. In this study, we conducted a pangenome-wide association study (panGWAS) on 9 blast resistance related phenotypes using 414 international diverse rice accessions from an international rice panel. This approach led to the identification of 74 QTLs associated with rice blast resistance. One notable locus, qPBR1, validated in a F4:5 population and fine-mapped in a Heterogeneous Inbred Family (HIF), exhibited broad-spectrum, major and durable blast resistance throughout the growth period. Furthermore, we performed transcriptomic analysis of 3 resistant and 3 sensitive accessions at different time points after infection, revealing 3,311 differentially expressed genes (DEGs) potentially involved in blast resistance. Integration of the above results identified 6 candidate genes within the qPBR1 locus, with no significant negative effect on yield. The results of this study provide valuable germplasm resources, QTLs, blast response genes and candidate functional genes for developing rice varieties with enduring and broad-spectrum blast resistance. The qPBR1, in particular, holds significant potential for breeding new rice varieties with comprehensive and durable resistance throughout their growth period.

Fine-mapping and molecular marker development for Pi56(t), a NBS-LRR gene conferring broad-spectrum resistance to Magnaporthe oryzae in rice.

The major quantitative trait locus qBR9.1 confers broad-spectrum resistance to rice blast, and was mapped to a ~69.1 kb region on chromosome 9 that was inherited from resistant variety Sanhuangzhan No 2 (SHZ-2). Within this region, only one predicted disease resistance gene with nucleotide binding site and leucine-rich repeat (NBS-LRR) domains was found. Specific markers corresponding to this gene cosegregated with blast resistance in F2 and F3 populations derived from crosses of susceptible variety Texianzhan 13 (TXZ-13) to SHZ-2 and the resistant backcross line BC-10. We tentatively designate the gene as Pi56(t). Sequence analysis revealed that Pi56(t) encodes an NBS-LRR protein composed of 743 amino acids. Pi56(t) was highly induced by blast infection in resistant lines SHZ-2 and BC-10. The corresponding allele of Pi56(t) in the susceptible line TXZ-13 encodes a protein with an NBS domain but without LRR domain, and it was not induced by Magnaporthe oryzae infection. Three new cosegregating gene-specific markers, CRG4-1, CRG4-2 and CRG4-3, were developed. In addition, we evaluated polymorphism of the gene-based markers among popular varieties from national breeding programs in Asia and Africa. The presence of the CRG4-2 SHZ-2 allele cosegregated with a blast-resistant phenotype in two BC2F1 families of SHZ-2 crossed to recurrent parents IR64-Sub1 and Swarna-Sub1. CRG4-1 and CRG4-3 showed clear polymorphism among 19 varieties, suggesting that they can be used in marker-assisted breeding to combine Pi56(t) with other target genes in breeding lines.

Association of plasma MMP-2 levels and prognosis of patients with intracerebral hemorrhage: a prospective cohort study.

Objective: The role of MMP-2 in patients with ICH is controversial and the impact of plasma MMP-2 level on clinical outcome is still unclear. Materials and methods: In this study, the peripheral venous blood was acquired from 93 patients with ICH and 88 healthy controls within 24 h of hospitalization and at enrollment. We retrospectively investigated plasma MMP-2 levels of patients and healthy controls. The edema volume, the NIHSS score, the GCS score, and mRS were used to assess and quantify neurological deficit following ICH. Logistic regression analysis was configured to determine the independent relation of plasma MMP-2 levels with clinical outcomes. In addition, the plasma MMP-14 levels and complement C4 level were tested to explore the relationship with plasma MMP-2 level. Results: There was a significant reduction of plasma MMP-2 levels in ICH patients than that in healthy controls (38.02 ± 1.71 vs. 54.03 ± 2.15, p < 0.0001), and MMP-2 is negatively correlated with the edema volume (r = -0.2187, p < 0.05), NIHSS score (r = -0.2194, p < 0.05), blood leucocyte count (r = -0.2549, p = 0.012), and complement C4 level (r = -0.2723, p = 0.005). There is positive correlation between MMP-2 level and GCS score (r = 0.2451, p = 0.01) and MMP-14 level (r = 0.7013, p = 0.005). The multivariate analysis revealed that reduced plasma MMP-2 level is associated with elevated edema volume (OR = 0.2604, 95% CI [0.07 to 0.84], p = 0.02). Conclusion: The plasma MMP-2 level in patients with ICH is significantly lower than that of healthy controls, and plasma MMP-2 level may be a prognostic factor. Plasma MMP-2 levels are correlated with the clinical outcomes of patients and negatively correlated with blood leucocyte count and complement C4 level in patients with ICH.