Genetic background impacts soluble and cell wall-bound aromatics in brown midrib mutants of sorghum.
Sorghum (Sorghum bicolor (L.). Moench) BMR-6 and BMR-12 encode cinnamylalcohol dehydrogenase and caffeic acid-O-methyltransferase, respectively. We have evaluated the impact of two bmr alleles, bmr-6 and bmr-12, respectively, on soluble and wall-bound aromatics in near isogenic, wild-type (WT), bmr-6, bmr-12 and double-mutant (DM; bmr-6 and bmr-12) plants in two genetic backgrounds, RTx430 and Wheatland. Immunoblots confirmed that COMT protein was essentially absent in bmr-12 and DM plants, but was present in bmr-6 and WT plants. In contrast, although CAD activity was not detected in bmr-6 and DM plants, proteins crossreacting to anti-CAD sera were found in stem extracts from all genotypes. In both sorghum backgrounds, WT plants had lowest amounts of free aromatics, higher levels of cell wall-bound pCA and FA esters and guaiacyl (G), syringyl (S), and p-hydroxyphenyl (H) lignins. Soluble aromatics and cell wall phenolic ester content in Wheatland DM plants resembled that of Wheatland bmr-6 plants, whereas in the RTx430 background, levels of these components in the DM plants more closely resembled those observed in bmr-12 plants. In both backgrounds, bmr-6 plants exhibited reduced levels of G, S, and H lignins relative to WT, and increased incorporation of G-indene into lignin. In bmr-12 plants, there was greater incorporation of G- and 5-hydroxyguaiacyl (5-OHG) lignin into cell walls. Histochemical staining of internode sections from Wheatland plants indicated that apparent lignification of cortical sclerenchyma and vascular bundle fibers was greatest and most uniform in WT plants. Relative staining intensity of these tissues was decreased in bmr-6, followed by bmr-12 plants. DM plants exhibited poor staining of cortical sclerenchyma and vascular bundle fibers.
Palmer
Nathan A
NA
Grain, Forage and Bioenergy Research Unit, USDA-ARS, University of Nebraska-Lincoln, East Campus, 314 Biochemistry Hall, Lincoln, NE 68583-0737, USA.
Sattler
Scott E
SE
Saathoff
Aaron J
AJ
Funnell
Deanna
D
Pedersen
Jeffery F
JF
Sarath
Gautam
G
D002473:Cell Wall / Q000378:metabolism*; D003373:Coumaric Acids / Q000378:metabolism; D004951:Esterification; D008401:Gas Chromatography-Mass Spectrometry; D006841:Hydrocarbons, Aromatic / Q000378:metabolism*; D015151:Immunoblotting; D008031:Lignin / Q000096:biosynthesis; D009154:Mutation / Q000235:genetics*; D010088:Oxidoreductases / Q000378:metabolism; D010940:Plant Proteins / Q000378:metabolism; D018547:Plant Stems / Q000166:cytology / Q000378:metabolism; D012995:Solubility; D045868:Sorghum / Q000166:cytology / Q000201:enzymology / Q000235:genetics* / Q000378:metabolism*; D014020:Tissue Extracts
D003373:Coumaric Acids; D006841:Hydrocarbons, Aromatic; D010940:Plant Proteins; D014020:Tissue Extracts; D008031:Lignin; C004999:ferulic acid; D010088:Oxidoreductases
Annu Rev Plant Biol. 2003;54:519-46
14503002
J Agric Food Chem. 2002 Jun 19;50(13):3789-94
12059161
J Biol Chem. 2000 Mar 3;275(9):6537-45
10692459
Planta. 1991 Nov;185(4):538-44
24186532
Nat Biotechnol. 2007 Jul;25(7):759-61
17572667
Proc Natl Acad Sci U S A. 1999 Aug 31;96(18):10045-50
10468559
Theor Appl Genet. 2002 Jan;104(1):127-31
12579437
J Ind Microbiol Biotechnol. 2008 May;35(5):343-354
18205019
Nature. 1970 Aug 15;227(5259):680-5
5432063
BMC Genomics. 2007 Jan 18;8:22
17233901
Plant J. 1998 Jun;14(5):545-53
9675900
Phytochemistry. 2002 Oct;61(3):221-94
12359514
Plant Physiol. 1993 Jun;102(2):481-489
12231836
Phytochemistry. 2001 Aug;57(7):1069-84
11430980
Bioresour Technol. 2007 Nov;98(16):2985-92
17156999
Proc Natl Acad Sci U S A. 2008 Jan 15;105(2):464-9
18180449
Plant Physiol Biochem. 2008 Mar;46(3):356-70
18272377
Planta. 2007 Jun;226(1):235-50
17226026
Mol Genet Genomics. 2003 May;269(2):205-14
12756532
J Biol Chem. 2002 Dec 6;277(49):47412-9
12351655
Planta. 2005 Mar;220(5):678-88
15452707
C R Biol. 2004 Sep-Oct;327(9-10):847-60
15587076
Phytochemistry. 2007 Jun;68(11):1521-9
17466347
Plant Mol Biol. 2006 Nov;62(4-5):697-714
17016741
Phytochemistry. 2007 Jul;68(14):1957-74
17467016
Planta. 2004 Nov;220(1):56-63
15252733
Planta. 2007 Aug;226(3):741-51
17457604
J Agric Food Chem. 2002 Sep 25;50(20):5558-65
12236679