Genotypic variation in sorghum [Sorghum bicolor (L.) Moench] exotic germplasm collections for drought and disease tolerance

Citation: Kapanigowda, M., . . . & Little, C. (2013). Genotypic variation in sorghum [Sorghum bicolor (L.) Moench] exotic germplasm collections for drought and disease tolerance. SpringerPlus, 2, 650. https://doi.org/10.1186/2193-1801-2-650Sorghum [Sorghum bicolor (L.) Moench] grain yield is severely affected by abiotic and biotic stresses during post-flowering stages, which has been aggravated by climate change. New parental lines having genes for various biotic and abiotic stress tolerances have the potential to mitigate this negative effect. Field studies were conducted under irrigated and dryland conditions with 128 exotic germplasm and 12 adapted lines to evaluate and identify potential sources for post-flowering drought tolerance and stalk and charcoal rot tolerances. The various physiological and disease related traits were recorded under irrigated and dryland conditions. Under dryland conditions, chlorophyll content (SPAD), grain yield and HI were decreased by 9, 44 and 16%, respectively, compared to irrigated conditions. Genotype RTx7000 and PI475432 had higher leaf temperature and grain yield, however, genotype PI570895 had lower leaf temperature and higher grain yield under dryland conditions. Increased grain yield and optimum leaf temperature was observed in PI510898, IS1212 and PI533946 compared to BTx642 (B35). However, IS14290, IS12945 and IS1219 had decreased grain yield and optimum leaf temperature under dryland conditions. Under irrigated conditions, stalk and charcoal rot disease severity was higher than under dryland conditions. Genotypes IS30562 and 1790E R had tolerance to both stalk rot and charcoal rot respectively and IS12706 was the most susceptible to both diseases. PI510898 showed combined tolerance to drought and Fusarium stalk rot under dryland conditions. The genotypes identified in this study are potential sources of drought and disease tolerance and will be used to develop better adaptable parental lines followed by high yielding hybrids

Genetic diversity and population structure among sorghum (Sorghum bicolor, L.) germplasm collections from Western Ethiopia

The Western Ethiopian region harbors a unique set of sorghum germplasm adapted to conditions not conventional to sorghums grown in other parts of the world. Accessions from the region possess unique resistance to multiple leaf and grain diseases. This study is aimed at exploring the extent of genetic variation and population structure among accessions of this region. A total of 123 accessions comprising 111 from Western Ethiopia (62 from Asosa and 49 from Pawe) and 12 U.S. adapted lines were genotyped using 30 sorghum simple sequence repeat markers (SSR). Genetic diversity and population structure were analyzed using PowerMarker and STRUCTURE software, respectively, based on 23 polymorphic SSR markers. Principal component analysis (PCA) was performed to view the variability in multi-dimensional space. Population structure analysis revealed considerable admixtures between Pawe and Asosa accessions, while the PowerMarker analysis grouped the accessions into three distinct clusters largely based on collection regions. The PCA did not clearly differentiate Asosa and Pawe accessions, but U.S. adapted lines were clearly separated from the rest. The study indicated the presence of marked genetic variability among accessions from Western Ethiopia and also provided clues on shared genetic events among accessions adapted to the two areas in Western Ethiopia.Keywords: Sorghum, genetic diversity, population structure, SSR, Ethiopi

Impact of deficit irrigation on sorghum physical and chemical properties and ethanol yield

The objective of this research was to study the effect of irrigation levels (five levels from 304.8 to 76.2 mm water) on the physical and chemical properties and ethanol fermentation performance of sorghum. Ten sorghum samples grown under semi-arid climatic conditions were harvested in 2011 from the Kansas State University Southwest Research-Extension Center near Garden City, Kansas, and evaluated. Irrigation had a significant effect on the physical properties, chemical composition, ethanol yield, and fermentation efficiency of sorghum. Sorghum kernel hardness increased and test weight decreased as the irrigation level decreased. Starch contents of sorghum samples grown under a low irrigation level were approximately 7% less than those grown under a high irrigation level. Protein contents ranged from 9.84% to 14.91% and increased as irrigation level decreased. Starch pasting temperature increased significantly, and starch peak pasting viscosity and setback viscosity decreased as the irrigation level decreased. Free amino nitrogen (FAN) increased significantly as irrigation decreased. Ethanol fermentation efficiency ranged from 90.6% to 91.9% and correlated positively with FAN during the first 30 h of fermentation (R² = 0.926). Deficit irrigation level had a negative impact on ethanol yield. The sorghum with low irrigation yielded about 8.9% less ethanol (434.52 mL ethanol per kg sorghum) than samples with higher irrigation (473.32 mL ethanol per kg sorghum). Residual starch contents in the distillers dried grains with solubles was less than 1% and ranged from 0.70% to 0.84%

Association mapping for grain quality in a diverse sorghum collection

Citation: Sukumaran, Sivakumar, Wenwen Xiang, Scott R. Bean, Jeffrey F. Pedersen, Stephen Kresovich, Mitchell R. Tuinstra, Tesfaye T. Tesso, Martha T. Hamblin, and Jianming Yu. “Association Mapping for Grain Quality in a Diverse Sorghum Collection.” The Plant Genome 5, no. 3 (2012): 126–35. https://doi.org/10.3835/plantgenome2012.07.0016.Knowledge of the genetic bases of grain quality traits will complement plant breeding efforts to improve the end-use value of sorghum [Sorghum bicolor (L.) Moench]. Candidate gene association mapping was used on a diverse panel of 300 sorghum accessions to assess marker–trait associations for 10 grain quality traits measured using the single kernel characterization system (SKCS) and near-infrared reflectance spectroscopy (NIRS). The analysis of the accessions through 1290 genomewide single nucleotide polymorphisms (SNPs) separated the panel into five subpopulations that corresponded to three major sorghum races (durra, kafir, and caudatum), one intermediate race (guinea-caudatum), and one working group (zerazera-caudatum). These subpopulations differed in kernel hardness, acid detergent fiber, and total digestible nutrients. After model testing, association analysis between 333 SNPs in candidate genes and/or loci and grain quality traits resulted in eight significant marker–trait associations. A SNP in starch synthase IIa (SSIIa) gene was associated with kernel hardness (KH) with a likelihood ratio-based R[superscript 2] (R[subscript LR][superscript 2]) value of 0.08, a SNP in starch synthase (SSIIb) gene was associated with starch content with an R[subscript LR][superscript 2] value of 0.10, and a SNP in loci pSB1120 was associated with starch content with an R[subscript LR][superscript 2] value of 0.09

Sorghum pathology and biotechnology - a fungal disease perspective: Part I. Grain mold, head smut, and ergot

Citation: Little, C., Perumal, R., Tesso, T., . . . & Magill, C. (2012). Sorghum Pathology and Biotechnology - A Fungal Disease Perspective: Part II. Anthracnose, Stalk Rot, and Downy Mildew. European Journal of Plant Science and Biotechnology, 6(1), 31-44. http://www.globalsciencebooks.info/Online/GSBOnline/images/2012/EJPSB_6(SI1)/EJPSB_6(SI1)31-44o.pdfThree common sorghum diseases, grain mold, head smut and ergot, each of which is directly related to seed production and quality are covered in this review. Each is described with respect to the causal organism or organisms, infection process, global distribution, pathogen variability and effects on grain production. In addition, screening methods for identifying resistant cultivars and the genetic basis for host resistance including molecular tags for resistance genes are described where possible

Sorghum pathology and biotechnology - a fungal disease perspective: Part II. Anthracnose, stalk rot, and downy mildew

Citation: Tesso, T., Perumal, R., Little, C., . . . Magill, C. (2011). Sorghum pathology and biotechnology - a fungal disease perspective: Part II. Anthracnose, stalk rot, and downy mildew. European Journal of Plant Science and Biotechnology, 6, 31-34.Foliar diseases and stalk rots are among the most damaging diseases of sorghum in terms of lost production potential, thus commanding considerable research time and expenditure. This review will focus on anthracnose, a fungal disease that causes both foliar symptoms and stalk rots along with the stalk rots caused by Fusarium spp. and Macrophomina phaseolina. Although the downy mildews are caused by oomycetes rather than true fungi, recent outbreaks have revealed resistance to previously effective chemical seed treatments and the evolution of new pathogenic races, once again pointing out the need for continuous vigilance. Sorghum diseases are described with respect to the causal organism or organisms, infection process, global distribution, pathogen variability and effects on grain production. In addition, screening methods for identifying resistant cultivars and the genetic basis for host resistance including molecular tags for resistance genes are described where possible along with prospects for future advances in more stable disease control