GC-MS Analysis of Hydrophobic Root Exudates of <i>Sorghum</i> and Implications on the Parasitic Plant <i>Striga asiatica</i>

Erickson, Jocelyn; Schott, Daniel; Reverri, Timothy; Muhsin, Waliyyah; Ruttledge, Thomas

doi:10.1021/jf0111099

Cited by 40 publications

(29 citation statements)

References 18 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Although very little variation in the levels of dihydrosorgoleone (measured as sorgoleone) was found between many of the high and low germination stimulant accessions (N13, P954063, SRN39, Framida and IS9830) used by study, others reported a nearly 30-fold variation among 25 sorghum varieties (Nimbal et al 1996). Some have also suggested that variations in the levels of resorcinol (methoxy-dihydrosorgoleone), a biochemically related metabolite, could stabilize dihydrosorgoleone, preserving its function and thereby modulating the Striga germination stimulant activity in the rhizosphere (Erickson et al 2001). Alkylresorcinol synthase 1 (ARS1), a sorghum gene involved in biosynthesis of dihydrosorgoleone, was recently identified on SBI-05 and cloned (Cook et al 2010; Phytozome database sorghum gene ID is Sb05g022500).…”

Section: Discussionmentioning

confidence: 99%

Molecular tagging and validation of microsatellite markers linked to the low germination stimulant gene (lgs) for Striga resistance in sorghum [Sorghum bicolor (L.) Moench]

et al. 2011

View full text Add to dashboard Cite

Striga is a devastating parasitic weed in Africa and parts of Asia. Low Striga germination stimulant activity, a well-known resistance mechanism in sorghum, is controlled by a single recessive gene (lgs). Molecular markers linked to the lgs gene can accelerate development of Striga-resistant cultivars. Using a high density linkage map constructed with 367 markers (DArT and SSRs) and an in vitro assay for germination stimulant activity towards Striga asiatica in 354 recombinant inbred lines derived from SRN39 (low stimulant) × Shanqui Red (high stimulant), we precisely tagged and mapped the lgs gene on SBI-05 between two tightly linked microsatellite markers SB3344 and SB3352 at a distance of 0.5 and 1.5 cM, respectively. The fine-mapped lgs region was delimited to a 5.8 cM interval with the closest three markers SB3344, SB3346 and SB3343 positioned at 0.5, 0.7 and 0.9 cM, respectively. We validated tightly linked markers in a set of 23 diverse sorghum accessions, most of which were known to be Striga resistant, by genotyping and phenotyping for germination stimulant activity towards both S. asiatica and S. hermonthica. The markers co-segregated with Striga germination stimulant activity in 21 of the 23 tested lines. The lgs locus similarly affected germination stimulant activity for both Striga species. The identified markers would be useful in marker-assisted selection for introgressing this trait into susceptible sorghum cultivars. Examination of the sorghum genome sequence and comparative analysis with the rice genome suggests some candidate genes in the fine-mapped region (400 kb) that may affect strigolactone biosynthesis or exudation. This work should form a foundation for map-based cloning of the lgs gene and aid in elucidation of an exact mechanism for resistance based on low Striga germination stimulant activity.

show abstract

Section: Discussionmentioning

confidence: 99%

Molecular tagging and validation of microsatellite markers linked to the low germination stimulant gene (lgs) for Striga resistance in sorghum [Sorghum bicolor (L.) Moench]

et al. 2011

View full text Add to dashboard Cite

show abstract

“…The term sorgoleone is most frequently used to describe the compound corresponding to the predominant congener identified in sorghum root exudates (Netzly et al, 1988;Kagan et al, 2003), 2-hydroxy-5-methoxy-3-[(Z,Z)-8',11',14'-pentadecatriene]-p-benzoquinone (Figure 1), which has been estimated to account for between ;40 and 90% of the exudate material (w/w) in various accessions (e.g., Nimbal et al, 1996;Czarnota et al, 2001;Baerson et al, 2008a;Dayan et al, 2009). The remaining exudate consists primarily of 4,6-dimethoxy-2-[(Z,Z)-8',11',14'-pentadecatriene]resorcinol (methoxy-dihydrosorgoleone) and sorgoleone congeners differing in the length or degree of saturation of the aliphatic side chain and in the substitution pattern of the quinone ring (Erickson et al, 2001;Kagan et al, 2003;Rimando et al, 2003;Dayan et al, 2009). The fact that sorgoleone acts as a potent broad-spectrum inhibitor active against many agronomically important monocotyledonous and dicotyledonous weed species and appears to affect multiple targets in vivo (e.g., Netzly and Butler, 1986;Einhellig and Souza, 1992;Nimbal et al, 1996;Rimando et al, 1998;Czarnota et al, 2001;Bertin et al, 2003;Duke, 2003) may make it promising for development as a natural product alternative to synthetic herbicides (Duke, 2003).…”

Section: Introductionmentioning

confidence: 99%

Alkylresorcinol Synthases Expressed in Sorghum bicolor Root Hairs Play an Essential Role in the Biosynthesis of the Allelopathic Benzoquinone Sorgoleone

et al. 2010

View full text Add to dashboard Cite

Sorghum bicolor is considered to be an allelopathic crop species, producing phytotoxins such as the lipid benzoquinone sorgoleone, which likely accounts for many of the allelopathic properties of Sorghum spp. Current evidence suggests that sorgoleone biosynthesis occurs exclusively in root hair cells and involves the production of an alkylresorcinolic intermediate (5-[(Z,Z)-89,119,149-pentadecatrienyl]resorcinol) derived from an unusual 16:3D 9,12,15 fatty acyl-CoA starter unit. This led to the suggestion of the involvement of one or more alkylresorcinol synthases (ARSs), type III polyketide synthases (PKSs) that produce 5-alkylresorcinols using medium to long-chain fatty acyl-CoA starter units via iterative condensations with malonyl-CoA. In an effort to characterize the enzymes responsible for the biosynthesis of the pentadecyl resorcinol intermediate, a previously described expressed sequence tag database prepared from isolated S. bicolor (genotype BTx623) root hairs was first mined for all PKS-like sequences. Quantitative real-time RT-PCR analyses revealed that three of these sequences were preferentially expressed in root hairs, two of which (designated ARS1 and ARS2) were found to encode ARS enzymes capable of accepting a variety of fatty acyl-CoA starter units in recombinant enzyme studies. Furthermore, RNA interference experiments directed against ARS1 and ARS2 resulted in the generation of multiple independent transformant events exhibiting dramatically reduced sorgoleone levels. Thus, both ARS1 and ARS2 are likely to participate in the biosynthesis of sorgoleone in planta. The sequences of ARS1 and ARS2 were also used to identify several rice (Oryza sativa) genes encoding ARSs, which are likely involved in the production of defense-related alkylresorcinols.

show abstract

“…The root hairs of sorghum produce an oily exudate containing the lipid benzoquinone sorgoleone (2-hydroxy-5-methoxy-3-[(8′Z, 11′Z)-8′, 11′, 14′-pentadecatriene]-p-benzoquinone), which is a potent allelochemical (Netzly and Butler, 1986;Inderjit and Duke, 2003). Sorgoleone and its 1 4-hydroquinone form together account for~50% of the oily exudates from sorghum root hairs (Erickson et al, 2001;Dayan et al, 2009). The remaining percentage consists primarily of alkyl resorcinol analogs, along with small amounts of several sorgoleone congeners that vary in the substitutions in the aromatic ring (Fate and Lynn, 1996;Rimando et al, 1998;Kagan et al, 2003).…”

Section: Introductionmentioning

confidence: 99%

Enhancing Sorgoleone Levels in Grain Sorghum Root Exudates

et al. 2010

View full text Add to dashboard Cite

Sorgoleone, found in the root exudates of sorghum [(Sorghum bicolor (L.) Moench], has been a subject of continued research. Sorgoleone production in grain sorghum roots was investigated under different growth conditions. Methanol was the most effective solvent for extracting sorgoleone from grain sorghum roots. Sorgoleone production is high in young developing plants. The maximum concentration (microg mg(-1) root dry weight) was produced in 5-d-old seedlings; beyond this age, production declined. However, considering both root weight and sorgoleone content per seedling, 10-d-old seedlings had the highest total amounts (microg). Compared with the control, sorgoleone content increased 6.1, 8.6, and 14.2 times when sorghum seeds were treated with auxins, Hoagland solution, and a combination of auxins and Hoagland solution, respectively. Among the innate immunity response elicitors, cellulose (an elicitor of plant origin) stimulated higher sorgoleone production than the others, and it produced 6.2 times more sorgoleone than the control. Combined treatment of sorghum seeds with half strength Hoagland solution and 5 microg ml(-1) of IBA significantly increased both root growth and sorgoleone content in sorghum seedlings.

show abstract

GC-MS Analysis of Hydrophobic Root Exudates of Sorghum and Implications on the Parasitic Plant Striga asiatica

Cited by 40 publications

References 18 publications

Molecular tagging and validation of microsatellite markers linked to the low germination stimulant gene (lgs) for Striga resistance in sorghum [Sorghum bicolor (L.) Moench]

Molecular tagging and validation of microsatellite markers linked to the low germination stimulant gene (lgs) for Striga resistance in sorghum [Sorghum bicolor (L.) Moench]

Alkylresorcinol Synthases Expressed in Sorghum bicolor Root Hairs Play an Essential Role in the Biosynthesis of the Allelopathic Benzoquinone Sorgoleone

Enhancing Sorgoleone Levels in Grain Sorghum Root Exudates

Contact Info

Product

Resources

About