Sweet Sorghum Genetic Diversity and Association Mapping for Brix and Height

Abstract

Sweet sorghum [Sorghum bicolor (L.) Moench], like its close relative, sugarcane (Saccharum spp.), has been selected to accumulate high levels of edible sugars in the stem. Sweet sorghums are tall and produce high biomass in addition to sugar. Little has been documented about the genetic relationships and diversity within sweet sorghums and how sweet sorghums relate to grain sorghum racial types. In this study, a diverse panel of 125 sorghums (mostly sweet) was successfully genotyped with 47 simple sequence repeats (SSRs) and 322 single nucleotide polymorphisms (SNPs). Using both distance-based and modelbased methods, we identifi ed three main genetic groupings of sweet sorghums. Based on observed phenotypes and known origins we classifi ed the three groups as historical and modern syrup, modern sugar/energy types, and amber types. Using SSR markers also scored in an available large grain sorghum germplasm panel, we found that these three sweet groupings clustered with kafi r/bicolor, caudatum, and bicolor types, respectively. Using the information on population structure and relatedness, association mapping was performed for height and stem sugar (brix) traits. Three signifi cant associations for height were detected. Two of these, on chromosomes 9 and 6, support published QTL studies. One signifi cant association for brix, on chromosome 1, 12kb from a glucose-6-phosphate isomerase homolog, was detected.

Variation de caractères agromorphologiques et du Brix d’une collection de sorghos à tige sucrée du Burkina Faso

“…L'accumulation des sucres semble liée à la capacité de la plante à développer une importante biomasse. Ritter et al (2008), Murray et al (2009) et Gutjahr (2012 ont également obtenu des corrélations significatives et positives entre le Brix, la hauteur de la plante, le poids sec de la tige et le cycle. La corrélation entre le Brix et le rendement en grains était par contre négative (Ritter et al, 2008).…”

“…Il regroupe différents écotypes dont la caractéristique commune est l'accumulation de quantités importantes d'hydrates de carbones dans leurs tiges juteuses (Ritter et al, 2008 ;Wang et al, 2013). Les principaux sucres contenus dans ce jus sont le saccharose, le glucose et le fructose, dans des proportions variables selon les variétés (Schaffer et Gourley, 1982 ;Murray et al, 2009). Selon Gutjahr (2012), les sorghos sucrés sont définis comme des sorghos de grande taille avec une importante biomasse.…”

“…Ils sont peu productifs et ont des grains de mauvaise qualité. Ces sorghos sont cultivés dans plusieurs pays comme les Etats-Unis (Ali et al, 2007 ;Murray et al, 2009 ;Wang et al, 2009), le Niger (Deu et al, 2008, la Chine (Zhang et al, 2009 ;Pei et al, 2010), la Guinée et le Mali (Sagnard et al, 2011). Le sorgho à tige sucrée est traditionnellement cultivé en Afrique où leurs tiges sont consommées comme friandises et leurs grains sont utilisés dans l'alimentation humaine et animale.…”

Duplicate and Conquer: Multiple Homologs ofPHOSPHORUS-STARVATION TOLERANCE1Enhance Phosphorus Acquisition and Sorghum Performance on Low-Phosphorus Soils

“…The Bayesian cluster analysis implemented in the STRUCTURE software (Pritchard et al, 2000) was used to estimate population structure in the association panel based on 310 SNPs distributed across the sorghum genome (Murray et al, 2009). The number of subpopulations, k, was allowed to vary from 1 to 12, with three independent runs for each value of k. The admixture model with correlated allele frequencies was adopted, with a burn-in length of 50,000 and a 50,000 run length, and a correction factor for Hardy-Weinberg equilibrium departure, l, was estimated with an independent run with k = 1.…”

Correlation and path coefficient analysis of agronomic and quality traits in a bioenergy crop, sweet sorghum [Sorghum bicolor (L.) Moench]

“…Therefore, selection for FSY needs to take into consideration PH, SD, BRX and JY. Significant genotypic variability among sweet sorghum germplasm was also reported by Ali et al (2008) and Murray et al (2009) for PH and juice BRX.…”