Scholarly Work - Plant Sciences & Plant Pathology
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Item A “solid” solution for wheat stem sawfly (Hymenoptera: Cephidae) resistance: Genetics, breeding and development of solid stem wheat(Wiley, 2023-06) Bathini, Akshara; Mendu, Lavanya; Pratap Singh, Nagendra; Cook, Jason; Weaver, David; Sherman, Jamie; Hager, Megan; Mondal, Suchismita; Mendu, VenugopalWheat (Triticum spp. L) production needs to be improved to meet the needs of a global population of >9 billion people by 2050. Increasing the productivity of the crop under conditions of abiotic and biotic stress to achieve food security continues to be a challenging proposition. Wheat stem sawfly (WSS) (Cephus cinctus Norton) has been considered as a serious pest of wheat since the late 19th century, causing devastating losses of wheat productivity in the Northern Great Plains of United States and regions of Canada. Developing resistant varieties of wheat that show consistent agronomic performances in varying environments is an effective strategy to manage WSS infestations. To achieve this goal, it is necessary to understand the underlying mechanisms of WSS infestation, damage, subsequent response of the host plant, and resulting yield losses. The review focuses on genetics, breeding, and development of solid stem (SS)-mediated WSS resistance in wheat since it has been the most effective method of genetic resistance in reducing wheat yield losses. Furthermore, the knowledge gaps that need to be addressed to develop an effective resistant cultivar against WSS are also discussed.Item Dosage response to reduced height‐1 (Rht‐1) loss‐of‐function mutations and characterization of slender phenotype in hexaploid wheat(Wiley, 2023-10) Ugrin, Josey M.; Hogg, Andrew C.; Tracy, Emma M.; Tillet, Brandon J.; Cook, Jason P.; Martin, John M.; Giroux, Michael J.The reduced height (Rht-1) genes in wheat (Triticum aestivum L.) are integral in controlling plant height. Previous studies in other plant species have demonstrated that loss-of-function mutations in their orthologous Rht-1 genes results in plants with a slender phenotype illustrated by increased plant heights, sterility, and a constitutive gibberellic acid (GA3) response; however, this phenotype has not been described in wheat. In this study, nonsense alleles occurring in the GRAS domain of Rht-A1, B1, and D1 were combined to create single, double, and triple Rht-1 mutants. Homozygous lines possessing none, one, two, or three Rht-1 stop mutations were grown in replicated field trials in three environments to assess agronomic traits. Germination tests to measure GA3 responsiveness and gene expression analysis via RNA-seq were also performed. Rht-1 triple mutants exhibited a slender phenotype characterized by rapid growth, elongated coleoptiles and internodes, elongated spikes, decreased tiller and spikelet number, and sterile heads. The presence of a single functional Rht-1 gene resulted in a normal phenotype. Differences in plant height among the Rht-1 double mutants, Rht-1 single mutants, and Rht-1 all wild-type dosages trended toward increased plant height with increased Rht-1 stop mutation dosage. Differences in Rht-1 homeolog gene expression did not equate to differences in plant height between the different Rht-1 stop mutations.Item A polyyne toxin produced by an antagonistic bacterium blinds and lyses a Chlamydomonad alga(Proceedings of the National Academy of Sciences, 2021-08) Hotter, Vivien; Zopf, David; Kim, Hak Joong; Silge, Anja; Schmitt, Michael; Aiyar, Prasad; Fleck, Johanna; Matthäus, Christian; Hniopek, Julian; Yan, Qing; Loper, Joyce; Sasso, Severin; Hertweck, Christian; Popp, Jürgen; Mittag, MariaAlgae are key contributors to global carbon fixation and form the basis of many food webs. In nature, their growth is often supported or suppressed by microorganisms. The bacterium Pseudomonas protegens Pf-5 arrests the growth of the green unicellular alga Chlamydomonas reinhardtii, deflagellates the alga by the cyclic lipopeptide orfamide A, and alters its morphology [P. Aiyar et al., Nat. Commun. 8, 1756 (2017)]. Using a combination of Raman microspectroscopy, genome mining, and mutational analysis, we discovered a polyyne toxin, protegencin, which is secreted by P. protegens, penetrates the algal cells, and causes destruction of the carotenoids of their primitive visual system, the eyespot. Together with secreted orfamide A, protegencin thus prevents the phototactic behavior of C. reinhardtii. A mutant of P. protegens deficient in protegencin production does not affect growth or eyespot carotenoids of C. reinhardtii. Protegencin acts in a direct and destructive way by lysing and killing the algal cells. The toxic effect of protegencin is also observed in an eyeless mutant and with the colony-forming Chlorophyte alga Gonium pectorale. These data reveal a two-pronged molecular strategy involving a cyclic lipopeptide and a conjugated tetrayne used by bacteria to attack select Chlamydomonad algae. In conjunction with the bloom-forming activity of several chlorophytes and the presence of the protegencin gene cluster in over 50 different Pseudomonas genomes [A. J. Mullins et al., bioRxiv [Preprint] (2021). https://www.biorxiv.org/content/10.1101/2021.03.05.433886v1 (Accessed 17 April 2021)], these data are highly relevant to ecological interactions between Chlorophyte algae and Pseudomonadales bacteria.Item A DeoR-Type Transcription Regulator Is Required for Sugar-Induced Expression of Type III Secretion-Encoding Genes in Pseudomonas syringae pv. tomato DC3000(Scientific Societies, 2020-03) Turner, Sydney E.; Pang, Yin-Yuin; O’Malley, Megan R.; Weisberg, Alexandra J.; Fraser, Valerie N.; Yan, Qing; Chang, Jeff H.; Anderson, AndersonThe type III secretion system (T3SS) of plant-pathogenic Pseudomonas syringae is essential for virulence. Genes encoding the T3SS are not constitutively expressed and must be induced upon infection. Plant-derived metabolites, including sugars such as fructose and sucrose, are inducers of T3SS-encoding genes, yet the molecular mechanisms underlying perception of these host signals by P. syringae are unknown. Here, we report that sugar-induced expression of type III secretion A (setA), predicted to encode a DeoR-type transcription factor, is required for maximal sugar-induced expression of T3SS-associated genes in P. syringae DC3000. From a Tn5 transposon mutagenesis screen, we identified two independent mutants with insertions in setA. When both setA::Tn5 mutants were cultured in minimal medium containing fructose, genes encoding the T3SS master regulator HrpL and effector AvrRpm1 were expressed at lower levels relative to that of a wild-type strain. Decreased hrpL and avrRpm1 expression also occurred in a setA::Tn5 mutant in response to glucose, sucrose, galactose, and mannitol, demonstrating that setA is genetically required for T3SS induction by many different sugars. Expression of upstream regulators hrpR/S and rpoN was not altered in setA::Tn5, indicating that SetA positively regulates hrpL expression independently of increased transcription of these genes. In addition to decreased response to defined sugar signals, a setA::Tn5 mutant had decreased T3SS deployment during infection and was compromised in its ability to grow in planta and cause disease. These data suggest that SetA is necessary for P. syringae to effectively respond to T3SS-inducing sugar signals encountered during infection.Item First Report of Powdery Mildew Caused by Erysiphe cruciferarum on Camelina sativa in Montana(Scientific Societies, 2022-07) Fu, Benzhong; Yan, QingCamelina sativa, also known as false flax, is an annual flowering plant in the family Brassicaceae that originated in Europe and Asia. In recent years, it has been cultivated as an important biofuel crop in Europe, Canada, and the northwest United States. In June 2021, severe powdery mildew disease was observed on C. sativa ‘Suneson’ plants under greenhouse conditions (temperature 18.3*C/22.2*C, night/day) in Bozeman, Montana (45*409 N, 111*29 W).Item Effect of the Monothiol Glutaredoxin GrxD on 2,4-Diacetylphloroglucinol Biosynthesis and Biocontrol Activity of Pseudomonas fluorescens 2P24(Frontiers Media SA, 2022-07) Dong, Qiuling; Yan, Qing; Zhang, Bo; Zhang, Li-qun; Wu, XiaogangPseudomonas fluorescens 2P24 is a plant root-associated bacterium that suppresses several soilborne plant diseases due to its production of the antibiotic 2,4-diacetylphloroglucinol (2,4-DAPG). The biosynthesis of 2,4-DAPG is controlled by many regulatory elements, including the global regulator of the Gac/Rsm regulon and the pathway-specific repressor PhlF. In this work, a novel genetic element grxD, which encodes the monothiol glutaredoxin GrxD, was identified and characterized in the production of 2,4-DAPG in P. fluorescens 2P24. Our data showed that the mutation of grxD remarkably decreased 2,4-DAPG production. GrxD lost its ability to alter the production of 2,4-DAPG when the active-site CGFS motif of GrxD was mutated by site-directed mutagenesis. Further studies showed that the RsmA and RsmE proteins were essential for the GrxD-mediated regulation of 2,4-DAPG and exoprotease production. In addition, our data revealed that the deletion of grxD increased the expression of phlF, which negatively regulated the production of 2,4-DAPG. In addition, the grxD mutant was severely impaired in the biocontrol effect against the bacterial wilt of tomato. Overall, our results indicated that the monothiol glutaredoxin GrxD is involved in the production of 2,4-DAPG of P. fluorescens by influencing the Gac/Rsm global signaling pathway and transcriptional regulator PhlF and is essential for the biocontrol properties.Item Identification and Characterization of Bacteria-Derived Antibiotics for the Biological Control of Pea Aphanomyces Root Rot(MDPI AG, 2022-08) Lai, Xiao; Niroula, Dhirendra; Burrows, Mary; Wu, Xiaogang; Yan, QingAntibiosis has been proposed to contribute to the beneficial bacteria-mediated biocontrol against pea Aphanomyces root rot caused by the oomycete pathogen Aphanomyces euteiches. However, the antibiotics required for disease suppression remain unknown. In this study, we found that the wild type strains of Pseudomonas protegens Pf-5 and Pseudomonas fluorescens 2P24, but not their mutants that lack 2,4-diacetylphloroglucinol, strongly inhibited A. euteiches on culture plates. Purified 2,4-diacetylphloroglucinol compound caused extensive hyphal branching and stunted hyphal growth of A. euteiches. Using a GFP-based transcriptional reporter assay, we found that expression of the 2,4-diacetylphloroglucinol biosynthesis gene phlAPf-5 is activated by germinating pea seeds. The 2,4-diacetylphloroglucinol producing Pf-5 derivative, but not its 2,4-diacetylphloroglucinol non-producing mutant, reduced disease severity caused by A. euteiches on pea plants in greenhouse conditions. This is the first report that 2,4-diacetylphloroglucinol produced by strains of Pseudomonas species plays an important role in the biocontrol of pea Aphanomyces root rot.Item Citrate Synthase GltA Modulates the 2,4-Diacetylphloroglucinol Biosynthesis of Pseudomonas fluorescens 2P24 and is Essential for the Biocontrol Capacity(American Chemical Society, 2023-07) Yang, Qingqing; Yan, Qing; Zhang, Bo; Zhang, Li-qun; Wu, XiaogangCarbon metabolism is critical for microbial physiology and remarkably affects the outcome of secondary metabolite production. The production of 2,4-diacetylphloroglucinol (2,4-DAPG), a bacterial secondary metabolite with a broad spectrum of antibiotic activity, is a major mechanism used by the soil bacterium Pseudomonas fluorescens 2P24 to inhibit the growth of plant pathogens and control disease occurrence. Strain 2P24 has evolved a complex signaling cascade to regulate the production of 2,4-DAPG. However, the role of the central carbon metabolism in modulating 2,4-DAPG production has not been fully determined. In this study, we report that the gltA gene, which encodes citrate synthase, affects the expression of the 2,4-DAPG biosynthesis gene and is essential for the biocontrol capacity of strain 2P24. Our data showed that the mutation of gltA remarkably decreased the biosynthesis of 2,4-DAPG. Consistent with this result, the addition of citrate in strain 2P24 resulted in increased 2,4-DAPG production and decreased levels of RsmA and RsmE. In comparison with the wild-type strain, the gltA mutant was severely impaired in terms of biocontrol activity against the bacterial wilt disease of tomato plants caused by Ralstonia solanacearum. Moreover, the gltA mutant exhibited increased antioxidant activity, and the expression of oxidative, stress-associated genes, including ahpB, katB, and oxyR, was significantly upregulated in the gltA mutant compared to the wild-type strain. Overall, our data indicate that the citrate synthase GltA plays an important role in the production of 2,4-DAPG and oxidative stress and is required for biocontrol capacity.Item Exopolysaccharide is required for motility, stress tolerance, and plant colonization by the endophytic bacterium Paraburkholderia phytofirmans PsJN(Frontiers Media SA, 2023-08) Fu, Benzhong; Yan, QingParaburkholderia phytofirmans PsJN is an endophytic bacterium and has been shown to promote the growth and health of many different plants. Exopolysaccharide (EPS) plays important roles in plant-bacteria interaction and tolerance to environmental stresses. However, the function of EPS in PsJN and its interaction with plants remain largely unknown. In this study, a deletion mutation of bceQ gene, encoding a putative flippase for the EPS biosynthesis, was introduced in the genome of PsJN. The ΔbceQ mutant produced a significantly lower level of EPS than the wild type strain in culture media. Compared to the wild type PsJN, the ΔbceQ mutant was more sensitive to desiccation, UV damage, salt (NaCl) and iron (FeCl3) stresses, and bacteriophage infection. More importantly, the mutation of bceQ decreased the endophytic colonization of PsJN in camelina (Camelina sativa) and pea (Camelina sativa) under plant drought stress conditions. To the best of our knowledge, this is the first report that EPS production is required for the maximal colonization of an endophytic bacterium in the plant tissues under stress conditions.Item Reconstitution of some tribes and genera of Lagriinae (Coleoptera, Tenebrionidae)(Pensoft Publishers, 2023-07) Aalbu, Rolf L.; Kanda, Kojun; Merkl, Ottó; Ivie, Michael A.; Andrew Johnston, M.The tribes Goniaderini Lacordaire, 1859 and Lupropini Lesne, 1926 within the tenebrionid subfamily Lagriinae Latreille, 1825 have previously been shown to be non-monophyletic by molecular phylogenetic analyses. The tribes and constituent genera are here reviewed and redefined morphologically. As part of tribal redefinitions, we establish PrateiniNew Tribe with type genus Prateus LeConte, 1862. We reestablish the subtribe Phobeliina Ardoin, 1961 Revised Status, which is transferred from Goniaderini and placed as a subtribe of Lagriini Latreille, 1825 where it is comprised of Phobelius Blanchard, 1842, and Rhosaces Champion, 1889 (previously in Lagriini: Statirina Blanchard, 1845). The fossil tribe Archaeolupropini Nabozhenko, Perkovsky, & Nazarenko, 2023 is transferred from Lagriinae to Tetratomidae: Tetratominae Billberg, 1820. Keys to extant tribes and subtribes of Lagriinae and genera of Goniaderini, Lupropini, and Prateini are provided. Generic and species-level changes from this work are as follows: Prateini is comprised of the following 15 genera: Antennoluprops Schawaller, 2007, Ardoiniellus Schawaller, 2013, Bolitrium Gebien, 1914, Enicmosoma Gebien, 1922, Indenicmosoma Ardoin, 1964, Iscanus Fauvel, 1904, Kuschelus Kaszab, 1982, Lorelopsis Champion, 1896, Mesotretis Bates, 1872, Microcalcar Pic, 1925, Micropedinus Lewis, 1894, Paratenetus Spinola, 1845, Prateus, Terametus Motschulsky, 1869, and Tithassa Pascoe, 1860. Lorelus Sharp, 1876 is Returned to Synonymy with Prateus, resulting in the following 49 New Combinations: Prateus angulatus (Doyen & Poinar, 1994), P. angustulus (Champion, 1913), P. armatus (Montrouzier, 1860), P. biroi (Kaszab, 1956), P. blairi (Kaszab, 1955), P. brevicornis (Champion, 1896), P. breviusculus (Champion, 1913), P. caledonicus (Kaszab, 1982), P. carolinensis (Blair, 1940), P. chinensis (Kaszab, 1940), P. clarkei (Kulzer, 1957), P. crassicornis (Broun, 1880), P. crassepunctatus (Kaszab, 1982), P. cribricollis (Kaszab, 1940), P. curvipes (Champion, 1913), P. dybasi (Kulzer, 1957), P. fijianus (Kaszab, 1982), P. fumatus (Lea, 1929), P. glabriventris (Kaszab, 1982), P. greensladei (Kaszab, 1982), P. guadeloupensis (Kaszab, 1940), P. hirtus (Kaszab, 1982), P. ivoirensis (Ardoin, 1969), P. kanak (Kaszab, 1986), P. kaszabi (Watt, 1992), P. laticornis (Watt, 1992), P. latulus (Broun, 1910), P. longicornis (Kaszab, 1982), P. mareensis (Kaszab, 1982), P. marginalis (Broun, 1910), P. niger (Kaszab, 1982), P. norfolkianus (Kaszab, 1982), P. obtusus (Watt, 1992), P. ocularis (Fauvel, 1904), P. opacus (Watt, 1992), P. palauensis (Kulzer, 1957), P. politus (Watt, 1992), P. priscus (Sharp, 1876), P. prosternalis (Kaszab, 1982), P. pubescens (Broun, 1880), P. pubipennis (Lea, 1929), P. punctatus (Watt, 1992), P. quadricollis (Broun, 1886), P. queenslandicus (Kaszab, 1986), P. rugifrons (Champion, 1913), P. solomonis (Kaszab, 1982), P. tarsalis (Broun, 1910), P. unicornis (Kaszab, 1982), and P. watti (Kaszab, 1982). Microlyprops Kaszab, 1939 is placed as a New Synonym of Micropedinus resulting in the following New Combinations: Micropedinus ceylonicus (Kaszab, 1939) and M. maderi (Kaszab, 1940). LorelopsisRevised Status is revalidated as a genus and eight species formerly in Lorelus are transferred to it resulting in the following six New Combinations: Lorelopsis bicolor (Doyen, 1993), L. glabrata (Doyen, 1993), L. exilis (Champion, 1913), L. foraminosa (Doyen & Poinar, 1994), L. minutulis (Doyen & Poinar, 1994), L. trapezidera (Champion, 1913), and L. wolcotti (Doyen, 1993). Lorelopsis pilosa Champion, 1896 becomes a Restored Combination. In Goniaderini, Aemymone Bates, 1868 Revised Status and Opatresthes Gebien, 1928 Revised Status, which were recently considered as subgenera of Goniadera Perty, 1832, are restored as valid genera based on new character analysis resulting in the following New Combinations: Aemymone hansfranzi (Ferrer & Delatour, 2007), A. simplex (Fairmaire, 1889), A. striatipennis (Pic, 1934) and Restored Combinations: Aemymone cariosa (Bates, 1868), A. crenata Champion, 1893, and A. semirufa Pic, 1917. Gamaxus Bates, 1868 is Returned to Synonymy with Phymatestes Pascoe, 1866, and the type species Gamaxus hauxwelli Bates, 1868 is placed as a New Synonym of Phymatestes brevicornis (Lacordaire, 1859). The following seven genera are placed as New Synonyms of Anaedus Blanchard, 1842: Microanaedus Pic, 1923, Pengaleganus Pic, 1917, Pseudanaedus Gebien, 1921, Pseudolyprops Fairmaire, 1882, Spinolyprops Pic, 1917, Spinadaenus Pic, 1921, and Sphingocorse Gebien, 1921. Fourteen species described by Pic in Aspisoma Duponchel & Chevrolat, 1841 (not Aspisoma Laporte, 1833) are returned to Tenebrionidae as valid species of Anaedus. These synonymies necessitate the following 51 New Combinations: Anaedus albipes (Gebien, 1921), A. amboinensis (Kaszab, 1964), A. amplicollis (Fairmaire, 1896), A. anaedoides (Gebien, 1921), A. angulicollis (Gebien, 1921), A. angustatus (Pic, 1921), A. australiae (Carter, 1930), A. bartolozzii (Ferrer, 2002), A. beloni Fairmaire, 1888), A. biangulatus (Gebien, 1921), A. borneensis (Pic, 1917), A. carinicollis (Gebien, 1921), A. conradti (Gebien, 1921), A. cribricollis (Schawaller, 2012), A. gabonicus (Pic, 1917), A. himalayicus (Kaszab, 1965), A. inaequalis (Pic, 1917), A. jacobsoni (Gebien, 1927), A. lateralis (Pic, 1917), A. latus (Pic, 1917), A. longeplicatus (Gebien, 1921) , A. maculipennis (Schawaller, 2011), A. major (Pic, 1917), A. nepalicus (Kaszab, 1975), A. nigrita (Gebien, 1927), A. notatus (Pic, 1923), A. pakistanicus (Schawaller, 1996), A. pinguis (Gebien, 1927), A. punctatus (Carter, 1914), A. raffrayi (Pic, 1917), A. rufithorax (Pic, 1917), A. rufus (Pic, 1917), A. serrimargo (Gebien, 1914), A. sumatrensis (Pic, 1917), A. terminatus (Gebien, 1921), A. testaceicornis (Pic, 1921), A. testaceipes (Pic, 1917), A. thailandicus (Schawaller, 2012), A. trautneri (Schawaller, 1994); and 13 restored combinations: Anaedus boliviensis (Pic, 1934), A. claveri (Pic, 1917), A. diversicollis (Pic, 1917), A. elongatus (Pic, 1934), A. guyanensis (Pic, 1917), A. holtzi (Pic, 1934), A. inangulatus (Pic, 1934), A. inhumeralis (Pic, 1917), A. mendesensis (Pic, 1917), A. minutus (Pic, 1917), A. rufimembris (Pic, 1932), A. rufipennis (Pic, 1917), A. subelongatus (Pic, 1932). The new synonymies with Anaedus necessitate the following six New Replacement NamesAnaedus maculipennis (for Spinolyprops maculatus Kulzer, 1954), A. grimmi (for Aspisoma forticornis Pic, 1917), A. minimus (for Anaedus minutus Pic, 1938), A. merkli (for Anaedus diversicollis Pic, 1938), A. ottomerkli (for Anaedus lateralis Pic, 1923), A. schawalleri (for Anaedus nepalicus Schawaller, 1994). Capeluprops Schawaller, 2011 is removed from Lupropini and provisionally placed in Laenini Seidlitz, 1895. Plastica Waterhouse, 1903 is transferred from Apocryphini Lacordaire, 1859 to Laenini. Paralorelopsis Marcuzzi, 1994 is removed from Lupropini and provisionally placed in Lagriinae incertae sedis. Pseudesarcus Champion, 1913 is transferred from Lagriinae incertae sedis to Diaperinae incertae sedis. Falsotithassa Pic, 1934 is transferred from Lupropini to Leiochrinini Lewis, 1894 (Diaperinae). Mimocellus Wasmann, 1904 is transferred from Lupropini to Tenebrionidae incertae sedis, and likely belongs in either Diaperinae or Stenochiinae.