Bx1 benzoxazin1

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Function Maize gene for first step in biosynthesis of benzoxazin, which aids in resistance to insect pests, pathogenic fungi and bacteria.

Contents

First report Hamilton 1964, [1] as a mutant sensitive to the herbicide atrazine, and lacking benzoxazinoids (less than 1% of non-mutant plants).

Molecular characterization reveals that the BX1 protein is a homologue to the alpha-subunit of tryptophan synthase. The reference mutant allele has a deletion of about 900 bp, located at the 5'-terminus and comprising sequence upstream of the transcription start site and the first exon. Additional alleles are given by a Mu transposon insertion in the fourth exon (Frey et al. 1997 [2] ) and a Ds transposon insertion in the maize inbred line W22 genetic background (Betsiashvili et al. 2014 [3] ). Gene sequence diversity analysis has been performed for 281 inbred lines of maize, and the results suggest that bx1 is responsible for much of the natural variation in DIMBOA (a benzoxazinoid compound) synthesis (Butron et al. 2010). [4] Genetic variation in benzoxazinoid content influences maize resistance to several insect pests (Meihls et al. 2013; [5] McMullen et al. 2009 [6] ).

Map location

AB chromosome translocation analyses place on short arm of chromosome 4 (4S; Simcox and Weber 1985 [7] ). There is close linkage to other genes in the benzoxazinoid synthesis pathway [bx2, bx3, bx4, bx5 Frey et al. 1995, [8] 1997 [2] ). Gene bx1 is 2490 bp from bx2 (Frey et al. 1997 [2] ); between umc123 and agrc94 on 4S (Melanson et al. 1997 [9] ). Mapping probes: SSR p-umc1022 (Sharopova et al. 2002 [10] ); Overgo (physical map probe) PCO06449 (Gardiner et al. 2004 [11] ).

Phenotypes

Mutants are viable, but may be distinguished from normal plants by FeCl3 staining: plants able to synthesize benzoxinoids have pale blue color when crushed and treated with FeCl3 solutions (Hamilton 1964, [1] Simcox 1993 [12] ). Mutations in the bx1 gene reduce the resistance to first generation European corn borer (Ostrinia nubilalis) that is conferred by benzoxazinoids (Klun et al. 1970 [13] ). Bx1 mutant maize deposited less callose in response to chitosan elicitation than isogenic wildtype plants (Ahmad et al. 2011 [14] ). Genetic mapping using recombinant inbred lines derived from maize inbred lines B73 and Mo17 showed that a 3.9 kb cis-regulatory element that is located approximately 140 kb upstream of Bx1 causes higher 2,4-dihydroxy-7-methoxy-1,4-benzoxazin-3-one (DIMBOA) accumulation in Mo17 than in B73 seedlings (Zheng et al. 2015 [15] ). This genetic variation is also associated with higher corn leaf aphid ( Rhopalosiphum maidis ) reproduction on B73 compared to Mo17 maize seedlings (Betsiashvili et al. 2014 [3] ). Relative to maize inbred line W22, Bx1::Ds mutant maize plants are more sensitive to corn leaf aphids ( Rhopalosiphum maidis ) (Betsiashvili et al. 2014 [3] ) and beet armyworms ( Spodoptera exigua ) (Tzin et al. 2017 [16] ). Highly localized induction of benzoxazinoid accumulation in response to Egyptian cotton leafworm ( Spodoptera littoralis ) feeding is abolished in a maize bx1 mutant (Maag et al. 2016 [17] ).

Gene Product

Catalyzes the first step in the synthesis of DIMBOA, forming indole from indole-3-glycerol phosphate. The enzyme is called indole-3-glycerol phosphate lyase, chloroplast, EC 4.1.2.8 and is located in the chloroplast. The X-ray structure of BX1 protein has been resolved and compared with bacterial TSA (tryptophan synthase alpha subunit, Kulik et al. 2005). [18] Three homologs of the BX1 protein occur in maize. One is encoded by the gene tsa1, tryptophan synthase alpha1(Frey et al. 1997, [2] Melanson et al. 1997 [9] ), on chromosome 7, another by igl1, indole-3-glycerol phosphate lyase1(Frey et al. 1997, [2] on chromosome 1, and another by tsah1, 'TSA like" and located near the bx1 gene (Frey et al. 1997. [2] ).

Related Research Articles

<span class="mw-page-title-main">Tryptophan synthase</span>

Tryptophan synthase or tryptophan synthetase is an enzyme that catalyses the final two steps in the biosynthesis of tryptophan. It is commonly found in Eubacteria, Archaebacteria, Protista, Fungi, and Plantae. However, it is absent from Animalia. It is typically found as an α2β2 tetramer. The α subunits catalyze the reversible formation of indole and glyceraldehyde-3-phosphate (G3P) from indole-3-glycerol phosphate (IGP). The β subunits catalyze the irreversible condensation of indole and serine to form tryptophan in a pyridoxal phosphate (PLP) dependent reaction. Each α active site is connected to a β active site by a 25 angstrom long hydrophobic channel contained within the enzyme. This facilitates the diffusion of indole formed at α active sites directly to β active sites in a process known as substrate channeling. The active sites of tryptophan synthase are allosterically coupled.

<span class="mw-page-title-main">Indole-3-acetic acid</span> Chemical compound

Indole-3-acetic acid is the most common naturally occurring plant hormone of the auxin class. It is the best known of the auxins, and has been the subject of extensive studies by plant physiologists. IAA is a derivative of indole, containing a carboxymethyl substituent. It is a colorless solid that is soluble in polar organic solvents.

<span class="mw-page-title-main">Waxy corn</span>

Waxy corn or glutinous corn is a type of field corn characterized by its sticky texture when cooked as a result of larger amounts of amylopectin. The corn was first described from a specimen from China in 1909. As this plant showed many peculiar traits, the American breeders long used it as a genetic marker to tag the existence of hidden genes in other maize breeding programs. In 1922 a researcher found that the endosperm of waxy maize contained only amylopectin and no amylose starch molecule in opposition to normal dent corn varieties that contain both. Until World War II, the main source of starch in the United States was tapioca, but when Japan severed the supply lines of the U.S., they forced processors to turn to waxy maize. Amylopectin or waxy starch is now used mainly in food products, but also in the textile, adhesive, corrugating and paper industry.

<span class="mw-page-title-main">Ajmaline</span> Chemical compound

Ajmaline is an alkaloid that is classified as a 1-A antiarrhythmic agent. It is often used to induce arrhythmic contraction in patients suspected of having Brugada syndrome. Individuals suffering from Brugada syndrome will be more susceptible to the arrhythmogenic effects of the drug, and this can be observed on an electrocardiogram as an ST elevation.

<span class="mw-page-title-main">DIMBOA</span> Chemical compound

DIMBOA (2,4-dihydroxy-7-methoxy-1,4-benzoxazin-3-one) is a naturally occurring hydroxamic acid, a benzoxazinoid. DIMBOA is a powerful antibiotic present in maize, wheat, rye, and related grasses,

The enzyme indole-3-glycerol-phosphate lyase catalyzes the chemical reaction

<span class="mw-page-title-main">Maize</span> Genus of grass cultivated as a food crop

Maize, also known as corn in North American- and Australian- English, is a cereal grain first domesticated by indigenous peoples in southern Mexico about 10,000 years ago. The leafy stalk of the plant gives rise to inflorescences which produce pollen and separate ovuliferous inflorescences called ears that when fertilized yield kernels or seeds, which are botanical fruits. The term maize is preferred in formal, scientific, and international usage as the common name because this refers specifically to this one grain whereas corn refers to any principal cereal crop cultivated in a country. For example, in North America and Australia corn is often used for maize, but in England and Wales it can refer to wheat or barley, and in Scotland and Ireland to oats.

Nested association mapping (NAM) is a technique designed by the labs of Edward Buckler, James Holland, and Michael McMullen for identifying and dissecting the genetic architecture of complex traits in corn. It is important to note that nested association mapping is a specific technique that cannot be performed outside of a specifically designed population such as the Maize NAM population, the details of which are described below.

<span class="mw-page-title-main">Ajmalicine</span> Chemical compound

Ajmalicine, also known as δ-yohimbine or raubasine, is an antihypertensive drug used in the treatment of high blood pressure. It has been marketed under numerous brand names including Card-Lamuran, Circolene, Cristanyl, Duxil, Duxor, Hydroxysarpon, Iskedyl, Isosarpan, Isquebral, Lamuran, Melanex, Raunatin, Saltucin Co, Salvalion, and Sarpan. It is an alkaloid found naturally in various plants such as Rauvolfia spp., Catharanthus roseus, and Mitragyna speciosa.

<i>Rhopalosiphum maidis</i> Species of true bug

Rhopalosiphum maidis, common names corn leaf aphid and corn aphid, is an insect, and a pest of maize and other crops. It has a nearly worldwide distribution and is typically found in agricultural fields, grasslands, and forest-grassland zones. Among aphids that feed on maize, it is the most commonly encountered and most economically damaging, particularly in tropical and warmer temperate areas. In addition to maize, R. maidis damages rice, sorghum, and other cultivated and wild monocots.

Indole-2-monooxygenase (EC 1.14.13.137, BX2 (gene), CYP71C4 (gene)) is an enzyme with systematic name indole,NAD(P)H:oxygen oxidoreductase (2-hydroxylating). This enzyme catalyses the following chemical reaction

Indolin-2-one monooxygenase (EC 1.14.13.138, BX3 (gene), CYP71C2 (gene)) is an enzyme with systematic name indolin-2-one,NAD(P)H:oxygen oxidoreductase (3-hydroxylating). This enzyme catalyses the following chemical reaction

3-hydroxyindolin-2-one monooxygenase (EC 1.14.13.139, BX4 (gene), CYP71C1 (gene)) is an enzyme with systematic name 3-hydroxyindolin-2-one,NAD(P)H:oxygen oxidoreductase (2-hydroxy-2H-1,4-benzoxazin-3(4H)-one-forming). This enzyme catalyses the following chemical reaction

2-Hydroxy-1,4-benzoxazin-3-one monooxygenase (EC 1.14.13.140, BX5 (gene), CYP71C3 (gene)) is an enzyme with systematic name 2-hydroxy-2H-1,4-benzoxazin-3(4H)-one,NAD(P)H:oxygen oxidoreductase (N-hydroxylating). This enzyme catalyses the following chemical reaction

2,4-dihydroxy-1,4-benzoxazin-3-one-glucoside dioxygenase (EC 1.14.20.2, BX6 (gene), DIBOA-Glc dioxygenase) is an enzyme with systematic name (2R)-4-hydroxy-3-oxo-3,4-dihydro-2H-1,4-benzoxazin-2-yl beta-D-glucopyranoside:oxygen oxidoreductase (7-hydroxylating). This enzyme catalyses the following chemical reaction

2,4,7-trihydroxy-1,4-benzoxazin-3-one-glucoside 7-O-methyltransferase is an enzyme with systematic name S-adenosyl-L-methionine:(2R)-4,7-dihydroxy-3-oxo-3,4-dihydro-2H-1,4-benzoxazin-2-yl β-D-glucopyranoside 7-O-methyltransferase. This enzyme catalyses the following chemical reaction

2,4-Dihydroxy-7-methoxy-2H-1,4-benzoxazin-3(4H)-one 2-D-glucosyltransferase is an enzyme with systematic name UDP-alpha-D-glucose:2,4-dihydroxy-7-methoxy-2H-1,4-benzoxazin-3(4H)-one 2-beta-D-glucosyltransferase. This enzyme catalyses the following chemical reaction

L-tryptophan—pyruvate aminotransferase is an enzyme with systematic name L-tryptophan:pyruvate aminotransferase. This enzyme catalyses the following chemical reaction

4-Hydroxy-7-methoxy-3-oxo-3,4-dihydro-2H-1,4-benzoxazin-2-yl glucoside beta-D-glucosidase (EC 3.2.1.182, DIMBOAGlc hydrolase, DIMBOA glucosidase) is an enzyme with systematic name (2R)-4-hydroxy-7-methoxy-3-oxo-3,4-dihydro-2H-1,4-benzoxazin-2-yl beta-D-glucopyranoside beta-D-glucosidase. This enzyme catalyses the following chemical reaction

<span class="mw-page-title-main">Benzoxazinone biosynthesis</span>

The biosynthesis of benzoxazinone, a cyclic hydroxamate and a natural insecticide, has been well-characterized in maize and related grass species. In maize, genes in the pathway are named using the symbol bx. Maize Bx-genes are tightly linked, a feature that has been considered uncommon for plant genes of a biosynthetic pathways. Especially notable are genes encoding the different enzymatic functions BX1, BX2 and BX8 and which are found within about 50 kilobases. Results from wheat and rye indicate that the cluster is an ancient feature. In wheat the cluster is split into two parts. The wheat genes Bx1 and Bx2 are located in close proximity on chromosome 4 and wheat Bx3, Bx4 and Bx5 map to the short arm of chromosome 5; an additional Bx3 copy was detected on the long arm of chromosome 5B. Recently, additional biosynthetic clusters have been detected in other plants for other biosynthetic pathways and this organization might be common in plants.

References

  1. 1 2 Hamilton, RH (1964). "A corn mutant deficient in 2,4-dihydroxy-7-methoxy-1,4-benzoxazin-3-one with an altered tolerance of atrazine". Weeds. 12 (1): 27–30. doi:10.2307/4040633. JSTOR   4040633.
  2. 1 2 3 4 5 6 Frey, M; Chomet, P; Glawischnig, E; Stettner, C; Grün, S; Winklmair, A; Eisenreich, W; Bacher, A; Meeley, RB; Briggs, SP; Simcox, K; Gierl, A (Aug 1, 1997). "Analysis of a chemical plant defense mechanism in grasses". Science. 277 (5326): 696–9. doi:10.1126/science.277.5326.696. PMID   9235894.
  3. 1 2 3 Betsiashvili, M.; Ahern, K. R.; Jander, G. (2015). "Additive effects of two quantitative trait loci that confer Rhopalosiphum maidis (corn leaf aphid) resistance in maize inbred line Mo17". Journal of Experimental Botany. 66 (2): 571–578. doi:10.1093/jxb/eru379. ISSN   0022-0957. PMC   4286405 . PMID   25249072.
  4. ↑ Butrón, A; Chen, YC; Rottinghaus, GE; McMullen, MD (Feb 2010). "Genetic variation at bx1 controls DIMBOA content in maize" (PDF). Theoretical and Applied Genetics. 120 (4): 721–34. doi:10.1007/s00122-009-1192-1. hdl: 10261/24875 . PMID   19911162. S2CID   33310126.
  5. ↑ Meihls, L. N.; Kaur, H.; Jander, G. (2012). "Natural Variation in Maize Defense against Insect Herbivores". Cold Spring Harbor Symposia on Quantitative Biology. 77: 269–283. doi: 10.1101/sqb.2012.77.014662 . ISSN   0091-7451. PMID   23223408.
  6. ↑ McMullen, Michael D.; Frey, Monika; Degenhardt, Jörg (2009), Bennetzen, Jeff L.; Hake, Sarah C. (eds.), "Genetics and Biochemistry of Insect Resistance in Maize", Handbook of Maize: Its Biology, Springer New York, pp. 271–289, doi:10.1007/978-0-387-79418-1_14, ISBN   9780387794174
  7. ↑ Simcox, K. D.; Weber, D. F. (1985). "Location of the Benzoxazinless (bx) Locus in Maize by Monosomic and B-A Translocational Analyses1". Crop Science. 25 (5): 827. doi:10.2135/cropsci1985.0011183X002500050024x.
  8. ↑ Frey, M; Kliem, R; Saedler, H; Gierl, A (Jan 6, 1995). "Expression of a cytochrome P450 gene family in maize". Molecular & General Genetics. 246 (1): 100–9. doi:10.1007/bf00290138. PMID   7823905. S2CID   29908288.
  9. 1 2 Melanson, D; Chilton, MD; Masters-Moore, D; Chilton, WS (Nov 25, 1997). "A deletion in an indole synthase gene is responsible for the DIMBOA-deficient phenotype of bxbx maize". Proceedings of the National Academy of Sciences of the United States of America. 94 (24): 13345–50. Bibcode:1997PNAS...9413345M. doi: 10.1073/pnas.94.24.13345 . PMC   24311 . PMID   9371848.
  10. ↑ Sharopova, N; McMullen, MD; Schultz, L; Schroeder, S; Sanchez-Villeda, H; Gardiner, J; Bergstrom, D; Houchins, K; Melia-Hancock, S; Musket, T; Duru, N; Polacco, M; Edwards, K; Ruff, T; Register, JC; Brouwer, C; Thompson, R; Velasco, R; Chin, E; Lee, M; Woodman-Clikeman, W; Long, MJ; Liscum, E; Cone, K; Davis, G; Coe EH, Jr (Mar–Apr 2002). "Development and mapping of SSR markers for maize". Plant Molecular Biology. 48 (5–6): 463–81. doi:10.1023/a:1014868625533. PMID   12004892. S2CID   25157785.
  11. ↑ Gardiner, J; Schroeder, S; Polacco, ML; Sanchez-Villeda, H; Fang, Z; Morgante, M; Landewe, T; Fengler, K; Useche, F; Hanafey, M; Tingey, S; Chou, H; Wing, R; Soderlund, C; Coe EH, Jr (Apr 2004). "Anchoring 9,371 maize expressed sequence tagged unigenes to the bacterial artificial chromosome contig map by two-dimensional overgo hybridization". Plant Physiology. 134 (4): 1317–26. doi:10.1104/pp.103.034538. PMC   419808 . PMID   15020742.
  12. ↑ Simcox, KD (1993). "Screening large populations for recessive bx1 genotypes; a variation of the FeCl3 root-tip squash assay". Maize Genetics Cooperation Newsletter. 67: 116. Retrieved Dec 24, 2013.
  13. ↑ Klun, Jerome A.; Guthrie, W. D.; Hallauer, Arnel R.; Russell, W. A. (1970). "Genetic Nature of the Concentration of 2,4-dihydroxy-7-methoxy 2H-l,4-benzoxazin- 3(4H)-one and Resistance to the European Corn Borer in a Diallel Set of Eleven Maize Inbreds1". Crop Science. 10 (1): 87. doi:10.2135/cropsci1970.0011183X001000010032x. ISSN   0011-183X.
  14. ↑ Ahmad, Shakoor; Veyrat, Nathalie; Gordon-Weeks, Ruth; Zhang, Yuhua; Martin, Janet; Smart, Lesley; Glauser, Gaétan; Erb, Matthias; Flors, Victor (2011). "Benzoxazinoid Metabolites Regulate Innate Immunity against Aphids and Fungi in Maize". Plant Physiology. 157 (1): 317–327. doi:10.1104/pp.111.180224. ISSN   0032-0889. PMC   3165881 . PMID   21730199.
  15. ↑ Zheng, Linlin; McMullen, Michael D.; Bauer, Eva; Schön, Chris-Carolin; Gierl, Alfons; Frey, Monika (2015). "Prolonged expression of the BX1 signature enzyme is associated with a recombination hotspot in the benzoxazinoid gene cluster in Zea mays". Journal of Experimental Botany. 66 (13): 3917–3930. doi:10.1093/jxb/erv192. ISSN   1460-2431. PMC   4473990 . PMID   25969552.
  16. ↑ Tzin, Vered; Hojo, Yuko; Strickler, Susan R; Bartsch, Lee J; Archer, Cairo M; Ahern, Kevin R; Zhou, Shaoqun; Christensen, Shawn A; Galis, Ivan (2017). "Rapid defense responses in maize leaves induced by Spodoptera exigua caterpillar feeding". Journal of Experimental Botany. 68 (16): 4709–4723. doi:10.1093/jxb/erx274. ISSN   0022-0957. PMC   5853842 . PMID   28981781.
  17. ↑ Maag, Daniel; Köhler, Angela; Robert, Christelle A.M.; Frey, Monika; Wolfender, Jean-Luc; Turlings, Ted C.J.; Glauser, Gaétan; Erb, Matthias (2016). "Highly localized and persistent induction of Bx1 -dependent herbivore resistance factors in maize". The Plant Journal. 88 (6): 976–991. doi: 10.1111/tpj.13308 . PMID   27538820.
  18. ↑ Kulik, V; Hartmann, E; Weyand, M; Frey, M; Gierl, A; Niks, D; Dunn, MF; Schlichting, I (Sep 23, 2005). "On the structural basis of the catalytic mechanism and the regulation of the alpha subunit of tryptophan synthase (TSA) from Salmonella typhimurium and BX1 from maize, two evolutionarily related enzymes". Journal of Molecular Biology. 352 (3): 608–20. doi:10.1016/j.jmb.2005.07.014. PMID   16120446.
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