植物抗病遗传Plant Disease-resistance Genetics

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Multi-functional roles of TaSSI2 involved in Fusarium head blight and powdery mildew resistance and drought tolerance

HU Li-qin, MU Jing-jing, SU Pei-sen, WU Hong-yan, YU Guang-hui, WANG Gui-ping, WANG Liang, MA Xin, LI An-fei, WANG Hong-wei, ZHAO Lan-fei, KONG Ling-rang

2018, 17 (2): 368-380. DOI: 10.1016/S2095-3119(17)61680-0

Abstract （692） PDF in ScienceDirect

The mutation of the gene encoding a stearoyl-acyl carrier protein fatty acid desaturase (ssi2) has been proved to enhance pathogen resistance in several plants, while it’s potential to regulate biotic and abiotic stresses in wheat is still unclear. In this study, we cloned TaSSI2 gene in wheat and provided several evidences of its involvement in multiple biological functions. By using barley stripe mosaic virus (BSMV)-induced gene silencing (VIGS) in wheat, it was found that TaSSI2 negatively regulated both powdery mildew and Fusarium head blight (FHB) resistance, which was consistent with the phenotype observed in knock-out mutants of Kronos. The expression of TaSSI2 was down-regulated by in vitro treatments of methyl jasmonate (MeJA), but positively regulated by salicylic acid (SA) and abscisic acid (ABA), implying the cross-talk between different hormone signaling pathways involved in wheat to regulate biotic stresses is still to be elucidated. Furthermore, the up-regulated expression of PR4 and PR5 indicated that TaSSI2 probably regulated FHB resistance by depressing the SA signaling pathway in wheat. In addition, the over-expression of TaSSI2 increased the content of linolenic acid (18:3) and subsequently enhanced drought tolerance of transgenic Brachypodium. This phenomenon might be associated with its subcellular localization in the whole cytosol, partly overlapping with Golgi apparatus and the secreted vesicles. As a stearoyl-acyl carrier protein fatty acid desaturase, TaSSI2 was proposed to be involved in cell lipid metabolism and carried targets out of the cell from membrane or wax synthesis, resulting in enhanced drought tolerance in plant.

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Population genetic structure of Chinese Puccinia triticina races based on multi-locus sequences

LIU Tai-guo, GE Run-jing, MA Yu-tong, LIU Bo, GAO Li, CHEN Wan-quan

2018, 17 (08): 1779-1789. DOI: 10.1016/S2095-3119(18)61923-9

Abstract （313） PDF in ScienceDirect

Puccinia triticina, the causal agent of wheat leaf rust, is one of the most devastating rust fungi attacking wheat worldwide. Seventy-six isolates of the wheat leaf rust pathogen from Yunnan, Sichuan, Gansu and Henan provinces, China, were tested on wheat leaf rust differentials and the population structure was analyzed using four presumably neutral partial sequence markers such as elongation factor-1α (EF-1α), glyceraldehyde-3-phosphate dehydrogenase (GAPDH), β-tubulin (TUB) and the second largest RNA polymerase subunit (RPB2). The phenotypic diversity of Yunnan and Sichuan populations was higher than that of Gansu and Henan populations. The four populations were separated into two clusters based on the pathogenic data. A total of 12 single nucleotide polymorphisms (SNPs) and 32 haplotypes were identified among the four sequences. The 32 haplotypes were divided into two clusters in a neighbor-joining tree. Bayesian analyses also identified two clusters. Pairwise Fst between populations in different regions were significantly different (P<0.05). Analysis of molecular variance (AMOVA) indicated that 68% of the total genetic variation was within populations.

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Genetic diversity and population structure of Commelina communis in China based on simple sequence repeat markers

YANG Juan, YU Hai-yan, LI Xiang-ju, DONG Jin-gao

2018, 17 (10): 2292-2301. DOI: 10.1016/S2095-3119(18)61906-9

Abstract （394） PDF in ScienceDirect

Commelina communis (Asiatic dayflower) is a troublesome weed in China. Genetic variation of 46 C. communis populations from different collection sites in our country was investigated using 12 simple sequence repeat (SSR) primer pairs. Polymorphism analysis results showed high level of genetic diversity among these populations. The alleles (bands) were amplified by these primer pairs. The polymorphic proportion was 18.25%, and the average polymorphism information content was 0.1330. The highest effective number of alleles was 1.9915 at locus YP33, and the lowest value was 1.0000 at both loci YP25 and YP31. C. communis showed major average observed heterozygosity value (0.8655) than that of average expected heterozygosity (0.1330). C. communis populations were divided into three groups on the basis of unweighted pair-group method with arithmetic mean cluster analysis (Dice genetic similarity coefficient=0.772) and genetic structure analysis (K=3), and a principal coordinate analysis. The results of this study further illustrated that C. communis populations contained abundant genetic information, and the 12 SSR markers could detect the microsatellite loci of C. communis genomic DNA. These results might indicate that C. communis maintains high genetic diversity among different populations.

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Pathogenesis-related protein genes involved in race-specific allstage resistance and non-race specific high-temperature adult-plant resistance to Puccinia striiformis f. sp. tritici in wheat

Sumaira Farrakh, Meinan Wang, Xianming Chen

2018, 17 (11): 2478-2491. DOI: 10.1016/S2095-3119(17)61853-7

Abstract （383） PDF （1008KB）（280）

Interactions of the stripe rust pathogen (Puccinia striiformis f. sp. tritici) with wheat plants activate a wide range of host responses. Among various genes involved in the plant-pathogen interactions, the expressions of particular pathogenesis-related (PR) protein genes determine different defense responses. Different types of resistance have been recognized and utilized for developing wheat cultivars for resistance to stripe rust. All-stage resistance can be detected in seedling stage and remains at high levels throughout the plant growth stages. This type of resistance is race-specific and not durable. In contrast, plants with only high-temperature adult-plant (HTAP) resistance are susceptible in seedling stage, but become resistant when plants grow older and the weather becomes warmer. HTAP resistance controlled by a single gene is partial, but usually non-race specific and durable. The objective of this study was to analyze the expression of PR protein genes involved in different types of wheat resistance to stripe rust. The expression levels of 8 PR protein genes (PR1, PR1.2, PR2, PR3, PR4, PR5, PR9 and PR10) were quantitatively evaluated at 0, 1, 2, 7 and 14 days after inoculation in single resistance gene lines of wheat with all-stage resistance genes YrTr1, Yr76, YrSP and YrExp2 and lines carrying HTAP resistance genes Yr52, Yr59, Yr62 and Yr7B. Races PSTv-4 and PSTv-37 for compatible and incompatible interactions were used in evaluation of PR protein gene expression in wheat lines carrying all-stage resistance genes in the seedling-stage experiment while PSTv-37 was used in the HTAP experiment. Analysis of quantitative real-time polymerase chain reaction (qRT-PCR) revealed that all of the PR protein genes were involved in the different types of resistance controlled by different Yr genes. However, these genes were upregulated at different time points and at different levels during the infection process among the wheat lines with different Yr genes for either all-stage resistance or HTAP resistance. Some of the genes were also induced in compatible interactions, but the levels were almost always higher in the incompatible interaction than in the compatible interaction at the same time point for each Yr gene. These results indicate that both salicylic acid and jasmonate signaling pathways are involved in both race-specific all-stage resistance and non-race specific HTAP resistance. Although expressing at different stages of infection and at different levels, these PR protein genes work in concert for contribution to different types of resistance controlled by different Yr genes.

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Molecular mapping of stripe rust resistance gene YrH9017 in wheat-Psathyrostachys huashanica introgression line H9017-14-16-5-3

MA Dong-fang, HOU Lu, SUN Cai, ZHANG Xing, YIN Jun-liang, GUO Qing-yun, ZHU Yong-xing

2019, 18 (1): 108-114. DOI: 10.1016/S2095-3119(18)62048-9

Abstract （314） PDF in ScienceDirect

Several new stripe rust pathogen races emerged in the wheat growing regions of China in recent years. These races were virulent to most of the designated wheat seedling resistance genes. Thus, it is necessary and worthwhile to identify new valuable resistant materials for the sake of diversifying resistant sources, pyramiding different resistance genes and achieving durable resistance. Here, we identified the resistance gene, temporarily designated as YrH9017, in wheat-Psathyrostachys huashanica introgression line H9017-14-16-5-3. A total of 146 F₂ plants and their derived F_2:3 families in a cross of Mingxian 169
and H9017-14-16-5-3 were used to evaluate seedling stripe rust response and as a mapping population. Finally, we constructed a genetic map including eight simple sequence repeat (SSR) markers and expressed sequence tag (EST) markers. YrH9017 was located on the long arm of chromosome 2A and closely linked with two EST-sequence tagged site (EST-STS) markers BG604577 and BE471201 at 1.3 and 1.8 cM distance, respectively. The two closest markers could be used for marker-assisted selection of YrH9017 in breeding.

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Seedling and adult plant resistance to leaf rust in 46 Chinese bread wheat landraces and 39 wheat lines with known Lr genes

ZHANG Pei-pei, Takele Weldu Gebrewahid, ZHOU Yue, LI Qing-luo, LI Zai-feng, LIU Da-qun

2019, 18 (5): 1014-1023. DOI: 10.1016/S2095-3119(19)62575-X

Abstract （204） PDF in ScienceDirect

Wheat leaf rust, caused by Puccinia triticina (Pt), is an important foliar disease that has an important influence on wheat yield. The most economic, safe and effective way to control the disease is growing resistant cultivars. In the present study, a total of 46 wheat landraces and 34 wheat lines with known Lr (leaf rust resistance) genes were inoculated with 16 Pt pathotypes for postulating seedling resistance gene(s) in the greenhouse. These cultivars and five wheat differential lines with adult plant resistance (APR) genes (Lr12, Lr22b, Lr34, Lr35 and Lr37) were also evaluated for identification of slow rusting resistance in the field trials in Baoding, Hebei Province of China in the 2014–2015 and 2015–2016 cropping seasons. Furthermore, 10 functional molecular markers closely linked to 10 known Lr genes were used to detect all the wheat genotypes. Results showed that most of the landraces were susceptible to most of the Pt pathotypes at seedling stage. Nonetheless, Lr1 was detected only in Hongtangliangmai. The field experimental test of the two environments showed that 38 landraces showed slow rusting resistance. Seven cultivars possessed Lr34 but none of the landraces contained Lr37 and Lr46. Lr genes namely, Lr9, Lr19, Lr24, Lr28, Lr29, Lr47, Lr51 and Lr53 were effective at the whole plant stage. Lr18, Lr36 and Lr45 had lost resistance to part of pathotypes at the seedling stage but showed high resistance at the adult plant stage. Lr34 as a slowing rusting gene showed good resistance in the field. Four race-specific APR genes Lr12, Lr13, Lr35 and Lr37 conferred good resistance in the field experiments. Seven race-specific genes, Lr2b, Lr2c, Lr11, Lr16, Lr26, Lr33 and LrB had lost resistance. The 38 landraces showed slow rusting resistance to wheat leaf rust can be used as resistance resources for wheat resistance breeding in China.

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Bioinformatic analysis and functional characterization of the cfem proteins in maize anthracnose fungus Colletotrichum graminicola

GONG An-dong, JING Zhong-ying, ZHANG Kai, TAN Qing-qun, WANG Guo-liang, LIU Wen-de

2020, 19 (2): 541-550. DOI: 10.1016/S2095-3119(19)62675-4

Abstract （161） PDF in ScienceDirect

Fungal secreted proteins that contain the Common in Fungal Extracellular Membrane (CFEM) domain are important for pathogenicity. The hemibiotrophic fungus Colletotrichum graminicola causes the serious anthracnose disease of maize. In this study, we identified 24 CgCFEM proteins in the genome of C. graminicola. Phylogenic analysis revealed that these 24 proteins (CgCFEM1–24) can be divided into 2 clades based on the presence of the trans-membrane domain. Sequence alignment analysis indicated that the amino acids of the CFEM domain are highly conserved and contain 8 spaced cysteines, with the exception that CgCFEM1 and CgCFEM24 lack 1 and 2 cysteines, respectively. Ten CgCFEM proteins with a signal peptide and without the trans-membrane domain were considered as candidate effectors and, thus were selected for structural prediction and functional analyses. The CFEM domain in the candidate effectors can form a helical-basket structure homologous to the Csa2 protein in Candida albicans, which is responsible for haem acquisition and pathogenicity. Subcellular localization analysis revealed that these effectors accumulate in the cell membrane, nucleus, and cytosolic bodies. Additionally, 5 effectors, CgCFEM6, 7, 8, 9 and 15, can suppress the BAX-induced programmed cell death in Nicotiana benthamiana with or without the signal peptide. These results demonstrate that these 10 CgCFEM candidate effectors with different structures and subcellular localizations in host cells may play important roles during the pathogenic processes on maize plants.

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Genome-wide association analysis for stripe rust resistance in spring wheat (Triticum aestivum L.) germplasm

Sher MUHAMMAD, Muhammad SAJJAD, Sultan Habibullah KHAN, Muhammad SHAHID, Muhammad ZUBAIR, Faisal Saeed AWAN, Azeem Iqbal KHAN, Muhammad Salman MUBARAK, Ayesha TAHIR, Muhammad Umer, Rumana KEYANI, Muhammad Inam AFZAL, Irfan MANZOOR, Javed Iqbal WATTOO, Aziz-ur REHMAN

2020, 19 (8): 2035-2043. DOI: 10.1016/S2095-3119(19)62841-8

Abstract （172） PDF in ScienceDirect

Stripe rust is a continuous threat to wheat crop all over the world. It causes considerable yield losses in wheat crop every year. Continuous deployment of adult plant resistance (APR) genes in newly developing wheat cultivars is the most judicious strategy to combat this disease. Herein, we dissected the genetics underpinning stripe rust resistance in Pakistani wheat germplasm. An association panel of 94 spring wheat genotypes was phenotyped for two years to score the infestation of stripe rust on each accession and was scanned with 203 polymorphic SSRs. Based on D´ measure, linkage disequilibrium (LD) exhibited between loci distant up to 45 cM. Marker-trait associations (MTAs) were determined using mixed linear model (MLM). Total 31 quantitative trait loci (QTLs) were observed on all 21 wheat chromosomes. Twelve QTLs were newly discovered as well as 19 QTLs and 35 previously reported Yr genes were validated in Pakistani wheat germplasm. The major QTLs were QYr.uaf.2AL and QYr.uaf.3BS (PVE, 11.9%). Dissection of genes from the newly observed QTLs can provide new APR genes to improve genetic resources for APR resistance in wheat crop.

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Diversity in metagenomic sequences reveals new pathogenic fungus associated with smut in Job’s tears

LI Xiang-dong, SHI Ming, PAN Hong, LU Xiu-juan, WEI Xin-yuan, LU Ping, LIAN Qi-xian, FU Yu-hua

2020, 19 (9): 2257-2264. DOI: 10.1016/S2095-3119(20)63164-1

Abstract （128） PDF in ScienceDirect

Smut is a serious disease in Job’s tears, also known as adlay, and contributes to the reduction of crop yield in agricultural fields. In this study, the key pathogenic fungi in adlay smut disease were first identified by internal transcribed spacer region (ITS) high-throughput sequencing and then used to elucidate the composition and diversity of the fungal community in adlay smut. Results indicate that an abundance of operational taxonomic units (OTUs) were detected in the infected involucres of flowering plants and the OTUs were classified to nine phyla, 20 classes, 45 orders, 90 families and 119 genera. A total of 4 986 OTUs clustered together, sharing six core OTUs in all samples, while 145 OTUs were shared among four geographical groups. The Shannon and Simpson indices ranged from 0.137–1.629 and 0.357–0.970, respectively. Community diversity ranked as Anshun (AS)>Qinglong (QL)>Xingren (XR)>Xingyi (XY) among the four geographical groups by Shannon and Simpson indices, exhibiting complex community diversities among accessions and geographical groups. The richness and diversity data imply a weak relationship between the accession community richness and geographical origins of samples. Two closely related fungal genera, Sporisorium and Ustilago, were implicated as causes of smut disease. The genus Sporisorium appears to be more commonly found among accessions and thus is more likely to be the fungal pathogen causing smut in adlay. This work can facilitate strategies to control and prevent smut infection to improve adlay yield.

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Identification and resistant characterization of legumes sources against Meloidogyne incognita #br#

Pornthip RUANPANUN, Prakit SOMTA

2021, 20 (1): 168-177. DOI: 10.1016/S2095-3119(20)63414-1

Abstract （117） PDF in ScienceDirect

Root-knot nematodes (RKNs; Meloidogyne spp.) are becoming a serious problem in legume production. This study identified Vigna genotypes exhibiting resistance to M. incognita (RKN) and characterized the modes of the resistance to M. incognita. In total, 279 accessions from 21 Vigna species were screened for resistance based on a galling index (GI) and an egg mass index (EI). Seven accessions were highly resistant to RKN with GI≤25, namely JP74716 (V. mungo var. mungo; cultivated black gram), JP107881 (V. nepalensis), JP229392 (V. radiata var. sublobata; wild mungbean), AusTRCF118141 (V. unguiculata subsp. unguiculata; cultivated cowpea), AusTRCF306385 (V. unguiculata subsp. unguiculata), AusTRCF322090 (V. vexillata var. vexillata; wild zombi pea) and JP235929 (V. vexillata var. vexillata). JP229392 and AusTRCF322090 were the most resistant accessions having EI values of 18.74 and 1.88, respectively. Continuous culture of M. incognita on both JP229392 and AusTRCF322090 resulted in a weakness in pathogenic ability for this RKN. The resistance in JP229392 and AusTRCF322090 to RKN appeared to be antibiosis that was associated with reduced nematode penetration, retardation of nematode development and impeding giant cell formation. The Vigna germplasm resistance to RKN identified in this study could be utilized as gene sources for the development of RKN-resistant Vigna cultivars.

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Identification of leaf rust resistance genes in common wheat varieties from China and foreign countries

LIU Yuan, Takele Weldu GEBREWAHID, ZHANG Pei-pei, LI Zai-feng, LIU Da-qun

2021, 20 (5): 1302-1313. DOI: 10.1016/S2095-3119(20)63371-8

Abstract （186） PDF in ScienceDirect

Wheat leaf rust, triggered by Puccinia triticina Eriks (Pt), is among the most important diseases of wheat worldwide. Deploying resistant varieties against leaf rust is the most effective, environmentally-friendly and economic way to control the disease. In the present study, 66 wheat varieties form China and foreign countries were tested with 17 Pt races for gene postulation during the seedling stage in the greenhouse. All the varieties were also planted to identify slow rusting responses to leaf rust at the adult plant stage in Baoding and Zhoukou field trials during the 2016/2017 to 2017/2018 cropping seasons. Moreover, 12 closely linked molecular markers to known leaf rust resistance (Lr) genes were used for assessing all the varieties. The results of both gene postulation and molecular marker identification showed that a total of eight Lr genes, Lr1, Lr10, Lr17, Lr20, Lr26, Lr34, Lr37 and Lr46, either singly or in combination were detected in 32 varieties. Known Lr genes were not identified in the remaining 34 varieties. Seventeen varieties were found to have slow rusting resistance. The resistance sources identified in this study can be used as resources for resistance against leaf rust in wheat breeding programs in China and the respective foreign countries.

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Jasmonic acid and ethylene signaling pathways participate in the defense response of Chinese cabbage to Pectobacterium carotovorum infection

CHEN Chang-long, YUAN Fang, LI Xiao-ying, MA Rong-cai, XIE Hua

2021, 20 (5): 1314-1326. DOI: 10.1016/S2095-3119(20)63267-1

Abstract （108） PDF in ScienceDirect

Chinese cabbage (Brassica rapa subsp. pekinensis) suffers from soft rot disease caused by Pectobacterium carotovorum (Pc). To uncover the mechanisms underlying the defense response of Chinese cabbage to Pc, we constructed a suppression subtractive hybridization (SSH) library from Pc-infected cabbage and obtained 1 919 non-redundant expressed sequence tags (ESTs), which were used for cDNA microarray. We detected 800 differentially expressed genes (DEGs) in cabbage at different time points post-Pc inoculation, which were further confirmed by quantitative real-time PCR. One quarter of these DEGs were involved in the biotic stress pathways visualized by MapMan. Among them, 8, 8, 1, 3, and 2 DEGs were related to jasmonic acid (JA), ethylene (ET), JA+ET, auxin, and abscisic acid (ABA) signaling pathways, respectively, while no DEG was detected for salicylic acid (SA) signaling. Assessment of phytohormone production in the Pc-infected leaves showed that JA and ET production was increased, while SA production was decreased. Treatment with JA, methyl jasmonate (MeJA), the ET precursor 1-aminocyclopropane-1-carboxylate (ACC), or combinations thereof, reduced the disease severity, and the JA and JA+ACC treatments were superior and performed equally well. Our findings suggest that JA and ET may act synergistically against Pc infection in Chinese cabbage, and JA-mediated signaling might be the most significant.

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Two novel gene-specific markers at the Pik locus facilitate the application of rice blast resistant alleles in breeding

TIAN Da-gang, CHEN Zi-qiang, LIN Yan, CHEN Zai-jie, LUO Jia-mi, JI Ping-sheng, YANG Li-ming, WANG Zong-hua, WANG Feng

2021, 20 (6): 1554-1562. DOI: 10.1016/S2095-3119(20)63272-5

Abstract （153） PDF in ScienceDirect

Blast, a disease caused by Magnaporthe oryzae, is a major constraint for rice production worldwide. Introgression of durable blast resistance genes into high-yielding rice cultivars has been considered a priority to control the disease. The blast resistance Pik locus, located on chromosome 11, contains at least six important resistance genes, but these genes have not been widely employed in resistance breeding since existing markers hardly satisfy current breeding needs due to their limited scope of application. In this study, two PCR-based markers, Pikp-Del and Pi1-In, were developed to target the specific InDel (insertion/deletion) of the Pik-p and Pi-1 genes, respectively. The two markers precisely distinguished Pik-p, Pi-1, and the K-type alleles at the Pik locus, which is a necessary element for functional genes from rice varieties. Results also revealed that only several old varieties contain the two genes, of which nearly half carry the K-type alleles. Therefore, these identified varieties can serve as new gene sources for developing blast resistant rice. The two newly developed markers will be highly useful for the use of Pik-p, Pi-1 and other resistance genes at the Pik locus in marker-assisted selection (MAS) breeding programs.

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The TaFIM1 gene mediates wheat resistance against Puccinia striiformis f. sp. tritici and responds to abiotic stress

SHI Bei-bei, WANG Juan, GAO Hai-feng, ZHANG Xiao-juan, WANG Yang, MA Qing

2021, 20 (7): 1849-1857. DOI: 10.1016/S2095-3119(20)63276-2

Abstract （144） PDF in ScienceDirect

Fimbrin, a regulator of actin cytoskeletal dynamics that participates in numerous physiological and biochemical processes, controls multiple developmental processes in a variety of tissues and cell types. However, the role of fimbrin in pathogen defense of wheat and the mechanisms have not been well studied. Here, we investigated that the expression of TaFIM1 gene of wheat was significantly induced in response to avirulent race of Puccinia striiformis f. sp. tritici (Pst) and silencing of TaFIM1 by virus-induced gene silencing method. The results show that silencing of TaFIM1 resulted in a reduction of resistance against the stripe rust indicated by both phenotypes and a histological examination of Pst growth. Additionally, the expression level of TaFIM1 gene was up-regulated under abiotic stresses. These findings suggest that TaFIM1 functions as a positive regulator of pathogen resistance of wheat plants and response to abiotic stress. Our work may show new light on understanding the roles of fimbrin in wheat.

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Bioinformatic analysis and functional characterization of CFEM proteins in Setosphaeria turcica

WANG Jian-xia, LONG Feng, ZHU Hang, ZHANG Yan, WU Jian-ying, SHEN Shen, DONG Jin-gao, HAO Zhi-min

2021, 20 (9): 2438-2449. DOI: 10.1016/S2095-3119(20)63342-1

Abstract （263） PDF in ScienceDirect

Common in Fungal Extracellular Membrane (CFEM) domains are uniquely found in fungal extracellular membrane proteins which are important for pathogens. This study identified 13 StCFEM proteins in the genome of Setosphaeria turcica, the hemibiotrophic fungus that causes northern corn leaf blight. Sequence alignment and WebLogo analysis of their CFEM domains indicated that the amino acids were highly conserved and that, with the exception of StCFEM1, 2, 3, and 6, they contained eight cysteines. Phylogenic analysis suggested that these 13 proteins (StCFEM1–13) could be divided into 2 clades based on the presence of the trans-membrane domain. Six StCFEM proteins with a signal peptide and without a trans-membrane domain were considered as candidate effector proteins. The CFEM domain in the candidate effector proteins could form a helical-basket structure homologous to Csa2 in Candida albicans. Transcriptome analysis suggested that the 13 genes were expressed during fungal infection and a yeast secretion assay revealed that these candidate effectors were secreted proteins. It was also found that StCFEM3, 4, and 5 couldn’t affect BAX/INF1-induced programmed cell death (PCD) in Nicotiana benthamiana and while StCFEM12 could suppress INF1-induced PCD, it showed no effect on BAX-induced PCD. This study found that there were 13 members of the S. turcica CFEM protein family and that StCFEM12 was a candidate effector. This study laid the foundation for illustrating the roles of CFEM proteins during the pathogenic processes of phytopathogens.

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Horizontal gene transfer of a syp homolog contributes to the virulence of Burkholderia glumae

WANG Sai, WANG Pei-hong, NIE Wen-han, CUI Zhou-qi, LI Hong-yu, WU Yan, Ayizekeranmu YIMING, FU Luo-yi, Iftikhar AHMAD, CHEN Gong-you, ZHU Bo

2021, 20 (12): 3222-3229. DOI: 10.1016/S2095-3119(20)63553-5

Abstract （176） PDF in ScienceDirect

Horizontal gene transfer (HGT) has been proved a major driving force in prokaryotic evolution. However, the molecular functions of these transferred genes in pathogenic bacteria especially plant pathogenic bacteria are still not fully investigated. In this study, the whole-genome in silico analysis was performed and found a syringopeptin synthetase (syp) homolog in Burkholderia glumae, which can cause bacterial panicle blight in rice, was predicted to be horizontally transferred from Pseudomonas ancestor with solid confidence by phylogenetic analysis. The comprehensive molecular experiments were performed to study the potential role of this gene in B. glumae. Inoculation of rice panicles with the syp mutant resulted in 60% lower disease index compared with the wild type (WT) parent strain, suggesting the requirement of syp for the full virulence of B. glumae. Chromatography analysis of exudates from B. glumae showed suppression of synthesis of metabolites analogous to syringopeptin in the mutants. All these data raise the possibility of HGT phenomenon in shaping the virulence and adaptation of B. glumae over evolutionary time.

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