The Sorghum (Sorghum bicolor) Brown Midrib 30 Gene Encodes a Chalcone Isomerase Required for Cell Wall Lignification

In sorghum (Sorghum bicolor) and other C4 grasses, brown midrib (bmr) mutants have long been associated with plants impaired in their ability to synthesize lignin. The brown midrib 30 (Bmr30) gene, identified using a bulk segregant analysis and next-generation sequencing, was determined to encode a chalcone isomerase (CHI). Two independent mutations within this gene confirmed that loss of its function was responsible for the brown leaf midrib phenotype and reduced lignin concentration. Loss of the Bmr30 gene function, as shown by histochemical staining of leaf midrib and stalk sections, resulted in altered cell wall composition. In the bmr30 mutants, CHI activity was drastically reduced, and the accumulation of total flavonoids and total anthocyanins was impaired, which is consistent with its function in flavonoid biosynthesis. The level of the flavone lignin monomer tricin was reduced 20-fold in the stem relative to wild type, and to undetectable levels in the leaf tissue of the mutants. The bmr30 mutant, therefore, harbors a mutation in a phenylpropanoid biosynthetic gene that is key to the interconnection between flavonoids and monolignols, both of which are utilized for lignin synthesis in the grasses.

Impact of foliar fungicides on disease and silage quality of brown midrib (BMR) corn hybrids in Wisconsin

Corn, Zea mays L., is one of the most widely grown crops in the United States due to its importance as a feed, food, and fuel crop. Silage is a high energy, fermented feed that uses the entire corn plant and is important for feeding dairy cows. Any disease that affects the plant’s physiology can reduce silage quality. The goal of this study was to evaluate fungicide treatments on silage corn hybrids to determine their effect on fungal diseases, including those caused by Fusarium graminearum, on silage quality. Foliar fungicide trials were conducted in Arlington, Wisconsin in 2018 and 2019 and included two brown-midrib silage hybrids. In-field disease ratings were collected for foliar disease symptoms, ear rot severity, and lodging. Harvested silage was analyzed for yield, quality parameters, and mycotoxin (deoxynivalenol, DON) concentration. There were significant differences in all measured parameters between years and hybrids; however, only the foliar disease ratings were consistently reduced by the use of fungicide treatments. DON concentrations were significantly lower for two fungicide treatments in one hybrid in 2019. There were no significant differences among the treatments used on yield or any quality parameters in this study. More research needs to be done to find potential fungicides that can consistently reduce F. graminearum damage and DON concentration in silage corn.

Sorghum Brown Midrib19 (Bmr19) Gene Links Lignin Biosynthesis to Folate Metabolism

Genetic analysis of brown midrib sorghum (Sorghum bicolor) mutant lines assembled in our program has previously shown that the mutations fall into four allelic groups, bmr2, bmr6, bmr12 or bmr19. Causal genes for allelic groups bmr2, bmr6 and bmr12, have since been identified. In this report, we provide evidence for the nature of the bmr19 mutation. This was accomplished by introgressing each of the four bmr alleles into nine different genetic backgrounds. Polymorphisms from four resequenced bulks of sorghum introgression lines containing either mutation, relative to those of a resequenced bulk of the nine normal midrib recurrent parent lines, were used to locate their respective causal mutations. The analysis confirmed the previously reported causal mutations for bmr2 and bmr6 but failed in the case of bmr12-bulk due to a mixture of mutant alleles at the locus among members of that mutant bulk. In the bmr19-bulk, a common G → A mutation was found among all members in Sobic.001G535500. This gene encodes a putative folylpolyglutamate synthase with high homology to maize Bm4. The brown midrib phenotype co-segregated with this point mutation in two separate F2 populations. Furthermore, an additional variant allele at this locus obtained from a TILLING population also showed a brown midrib phenotype, confirming this locus as Bmr19.

Analisis Pertumbuhan Mindi (Melia azedarach L.) dan Produktivitas Sorgum (Sorghum bicolor L.) Galur G55 dan BIOSS-04 dalam Sistem Agroforestri

needs was decreasing. So it needs a system that maximizes land one of them is agroforestry. Agroforestry will combine mindi tree (Melia azedarach L.) were 2 years old with a spacing of 2.5 mx 2.5 m, and agricultural crops is sorgum strain of SEAMEO BIOTROP development results that G55 is a BMR (Brown midrib) strain and BIOSS 04 which belonging in sweet sorghum. The research purpose is to analyze the growth of mindi on agroforestry systems and monoculture and analyze the growth and productivity of sorghum on agroforestry systems and monoculture. The results showed growth of mindi as high tree, diameter of stem, canopy and root diameter larger on agroforestry than monocultures. Growth and productivity of sorghum in the two strains showed lower on agroforestry cropping pattern. Sorghum G55 and BIOSS 04 strains can grow under mindi trees but can not produce optimally. Keywords: Agroforestri, Melia azedarach, Sorghum bicolor