Chinese Sorghum Research Articles

The Genetic Diversity of 69 Widely Used Chinese Sorghum Hybrids Released between the 1970s and 2010s

Sorghum has a long history of cultivation in China. In this study, we aimed to clarify the genetic relationships and genetic variation trends in widely used Chinese sorghum hybrids which were released from the 1970s to 2010s and attempted to analyze the changes in sorghum breeding. A total of 257 alleles were detected by 51 polymorphic SSR markers among 69 widely used hybrids; an average of 5.04 alleles were detected by each marker. The average Shannon’s index and polymorphism information content (PIC) of markers were 1.39 and 0.70, respectively. Nei’s genetic diversity index continuously increased in four different breeding development stages (1973–1982, 1983–1992, 1993–2002, and 2003–2014). Genetic diversity gradually increased among the sorghum hybrids. Genetic similarity coefficients in the four breeding development stages first showed an increasing trend, and then a decreasing trend, finally stabilizing with an average value of 0.65. The genetic similarity changes in hybrids in early and late maturing areas were consistent at different breeding development stages. The genetic similarity coefficients in late maturing areas were constantly higher than those in the early maturing areas. This is related to China’s creative utilization of A2 cytoplasmic male sterile materials in the 1990s. A cluster analysis determined that 69 hybrids were divided into two groups, A and B. Group A could be further subdivided into four subgroups. These findings could provide a reference for parental selection and hybrid breeding in sorghum improvement programs.

Research on Genotype Markers for Plant Height and Assisted Breeding of Key Sorghum Resources in China.

Dwarfing and the selection of optimal plant types constitute the primary focus of sorghum breeding. However, the lack of clarity regarding the gene types associated with plant height genes Dw1-Dw4 in the primary breeding materials has led to increased plant heights in improved offspring of the same plant height type, resulting in unsatisfactory morphological traits. This study aimed to elucidate the gene types related to plant height in breeding materials, validate the regulatory mechanisms, and establish a material improvement system. The goal was to achieve molecular-marker-assisted dwarf breeding through the detection of plant height genes and the test cross verification of main Chinese sorghum materials. Using 38 main male sterile lines and 57 main restorer lines of grain sorghum as materials, three plant height genes were detected and classified. Ninety-five F1 generation hybrids of these materials, along with typical materials, were measured at the wax maturity stage. Test cross results demonstrated that the variation in dw1-dw3 genes in the breeding materials significantly influenced the plant height of hybrid offspring. The main male sterile lines in Chinese sorghum predominantly exhibited the "three-dwarf" type of Kafir and its improved lines, characterized by the genotype (Dw1-Dw2-dw3-dw4). On the other hand, restorer lines mainly showcased the improved "two-dwarf" (Dw1-Dw2-dw3-dw4) genotype of the Kaoliang/Caudatum subspecies, along with the "three-dwarf" type of some Kafir and its improved lines. The test materials predominantly contained dw3 genes, with relatively fewer dw1 genes in the restorer lines. The primary restorer materials lacked the dw2 gene, and dw2 significantly influenced plant type. The increased plant height in improved offspring of the same plant height type material was attributed to differences in gene types. Therefore, the enhancement of plant height in breeding materials should prioritize the use of different methods in conjunction with Dw1 and Dw2 classification.

GWAS of grain color and tannin content in Chinese sorghum based on whole-genome sequencing

Key messageSeventy-three QTL related to grain color and tannin content were identified in Chinese sorghum accessions, and a new recessive allelic variant of TAN2 gene was discovered.Sorghum is mainly used for brewing distilled liquors in China. Since grain tannins play an important role in liquor brewing, accurately understanding the relationship between grain color and tannin content can provide basis for selection standards of tannin sorghum. We resequenced a panel of 242 Chinese sorghum accessions and performed population structure and genome-wide association study (GWAS) to identify quantitative trait locus (QTL) affecting pericarp color, testa pigment, and tannin content. Phylogenetic analysis, principal component analysis (PCA), and admixture model were used to infer population structure. Two distinct genetic sub-populations were identified according to their corresponding northern and southern geographic origin. To investigate the genetic basis of natural variation in sorghum grain color, GWAS with 2,760,264 SNPs was conducted in four environments using multiple models (Blink, FarmCPU, GLM, and MLM). Seventy-three QTL were identified to be associated for the color of exocarp, mesocarp, testa, and tannin content on all chromosomes except chromosome 5, of which 47 might be novel QTL. Some important QTL were found to colocalize with orthologous genes in the flavonoid biosynthetic pathway from other plants, including orthologous of Arabidopsis (Arabidopsis thaliana) TT2, TT7, TT12, TT16 and AT5G41220 (GST), as well as orthologous of rice (Oryza sativa) MYB61 and OsbHLH025. Our investigation of the variation in grain color and tannin content in Chinese sorghum germplasm may help guide future sorghum breeding for liquor brewing.

First Report on Colletotrichum fructicola Causing Anthracnose in Chinese Sorghum and Its Management Using Phytochemicals.

Sorghum bicolor is cultivated worldwide. Leaf spots on sorghum, which lead to leaf lesions and impaired growth, are prevalent and severe in Guizhou Province, Southwest China. In August 2021, new leaf spot symptoms were observed on sorghum plants growing in agricultural fields. We used conventional tissue isolation methods and pathogenicity determination tests. Inoculations of sorghum with isolate 022ZW resulted in brown lesions similar to those observed under field conditions. The original inoculated isolates were reisolated and fulfilled Koch's postulates. Based on the morphological character and phylogenetic analyses of the combined sequences of the internal transcribed spacer (ITS) region and the β-tubulin (TUB2) and glyceraldehyde-3-phosphate dehydrogenase (GAPDH) genes, we identified the isolated fungus as C. fructicola. This paper is the first to report this fungus-causing disease in sorghum leaves. We studied the sensitivity of the pathogen to various phytochemicals. The sensitivity of C. fructicola to seven phytochemicals was measured using the mycelial growth rate method. Honokiol, magnolol, thymol, and carvacrol displayed good antifungal effects, with EC50 (concentration for 50% of the maximal effect) values of 21.70 ± 0.81, 24.19 ± 0.49, 31.97 ± 0.51, and 31.04 ± 0.891 µg/mL, respectively. We tested the control effect of the seven phytochemicals on the anthracnose caused by C. fructicola: honokiol and magnolol displayed good field efficacy. In this study, we expand the host range of C. fructicola, providing a basis for controlling sorghum leaf diseases caused by C. fructicola.

Prediction of available energy and amino acid digestibility of Chinese sorghum fed to growing-finishing pigs.

Two experiments were conducted to determine digestible energy (DE), metabolizable energy (ME), as well as the standardized ileal digestibility (SID) of crude protein (CP) and amino acids (AA) in 10 sorghum samples fed to pigs. In experiment 1, 22 crossbred barrows (Duroc × Yorkshire × Landrace, Initial body weight [BW]: 70.0 ± 1.8 kg) were selected and allotted to a replicated 11 × 3 incomplete Latin square design, including a basal diet and 10 sorghum energy diets and three consecutive periods. Each period had 7 d adaptation and 5 d total feces and urine collection. The DE and ME were determined by the total collection and the difference method. In experiment 2, 22 crossbred barrows (Duroc × Yorkshire × Landrace, Initial BW: 41.3 ± 1.2 kg) that had a T-cannula installed in the distal ileum were assigned to a replicated 11 × 3 incomplete Latin square design, including an N-free diet and 10 sorghum diets. Each period had 5 d adaptation and 2 d ileal digesta collection. The basal endogenous N losses were measured by the N-free diet method. All diets in experiment 2 were added 0.30% titanium dioxide as an indigestible marker for calculating the ileal CP and AA digestibility. On an as-fed basis, the DE and ME contents in sorghum were 3,410 kcal/kg (2,826 to 3,794 kcal/kg) and 3,379 kcal/kg (2,785 to 3,709 kcal/kg), respectively. The best-fit prediction equation for DE and ME were DE = 6,267.945 - (1,271.154 × % tannin) - (1,109.720 × % ash) (R2 = 0.803) and ME = 51.263 + (0.976 × DE) (R2 = 0.994), respectively. The SID of CP, Lys, Met, Thr, and Trp (SIDCP, SIDLys, SIDMet, SIDThr, and SIDTrp) in 10 sorghum samples were 78.48% (69.56% to 84.23%), 74.27% (61.11% to 90.60%), 92.07% (85.16% to 95.40%), 75.46% (66.39% to 80.80%) and 87.99% (84.21% to 92.37%), respectively. The best prediction equations for SID of CP and the first four limiting AAs were as following: SIDCP = 93.404 - (21.026 × % tannin) (R2 = 0.593), SIDCP = 42.922 - (4.011 × % EE) + (151.774 × % Met) (R2 = 0.696), SIDLys = 129.947 - (670.760 × % Trp) (R2 = 0.821), SIDMet = 111.347 - (232.298 × % Trp) (R2 = 0.647), SIDThr = 55.187 + (3.851 × % ADF) (R2 = 0.609) and SIDTrp = 95.676 - (10.824 × % tannin) (R2 = 0.523), respectively. Overall, tannin and ash are the first and second predictors of DE and ME values of sorghum, respectively, and the tannin, EE, Trp, ash, CF, and ADF can be used as the key predictors for SID of CP and first four limiting AAs.

Selection Signatures in Chinese Sorghum Reveals Its Unique Liquor-Making Properties.

Chinese sorghum (S. bicolor) has been a historically critical ingredient for brewing famous distilled liquors ever since Yuan Dynasty (749 ∼ 652 years BP). Incomplete understanding of the population genetics and domestication history limits its broad applications, especially that the lack of genetics knowledge underlying liquor-brewing properties makes it difficult to establish scientific standards for sorghum breeding. To unravel the domestic history of Chinese sorghum, we re-sequenced 244 Chinese sorghum lines selected from 16 provinces. We found that Chinese sorghums formed three distinct genetic sub-structures, referred as the Northern, the Southern, and the Chishui groups, following an obviously geographic pattern. These sorghum accessions were further characterized in liquor brewing traits and identified selection footprints associated with liquor brewing efficiency. An importantly selective sweep region identified includes several homologous genes involving in grain size, pericarp thickness, and architecture of inflorescence. Our result also demonstrated that pericarp strength rather than grain size determines the ability of the grains to resist repeated cooking during brewing process. New insight into the traits beneficial to the liquor-brewing process provides both a better understanding on Chinese sorghum domestication and a guidance on breeding sorghum as a multiple use crop in China.

Germination percentage and emergence potential of nine newly introduced temperate forage germplasms in Shika, Nigeria

A trial was conducted to investigate the germination percentage and emergence potential of nine imported temperate forage germplasms at the National Animal Production Research Institute, Shika, Nigeria. The seeds consisted of seven grasses namely; Beefsteak plant (Fructus perillae), Sweet elephant grass (Pennisetum alopecuroides), Wild foxtail millet (Setaria viridis), Napier grass (Pennisetum purpureum), King grass (Pennisetum sinese), Chinese sorghum (Sweet sorghum) and Zea mexican schard (Purus frumentum) and two legumes namely; Chinese woad (Isatis tinctoria) and Chinese alfalfa (Medicago sativa). A laboratory germination test and pot emergence trial was carried out to ascertain their viability. The result of the experiment showed that Sweet elephant grass, napier grass and king grass recorded over 90 % germination and the least was 30 % in Chinese sorghum. Chinese alfalfa and wild foxtail millet had least germination percentage with 100 % Seed dormancy.Highest emergence rate, seedling length and seedling vigour indexwere observed in king grass than the other forage germplasms. The highest percentage emergence was obtained in king grass > sweet elephant grass > napier grass > Zea mexican schard > beefsteak plant > Chinese woad > Chinese sorghum, respectively. It was concluded that these forages can successfully be adopted as animal feed resources in Nigeria and therefore, recommended formulti-locational trials in all the ecological zones of the country.

Screening and identification of Chinese sorghum landraces for salt tolerance at germination and seedling stages

<p indent=0mm>The deterioration of soil salinization has caused great harm to modern agricultural production in the world. Sorghum is not only one of five main crops, but also an outstanding salt tolerant crop. The screening and identification of sorghum salt toletion of sorghum salt tolerance will be very important to the development and utilization of salinized land, increasing grain yield and maintaining sustainable agricultural development. In this experiment, 110 sorghum landraces were selected to test salt tolerance at germination <sc>(200 mmol L^-1</sc> NaCl treated) and seedling stages <sc>(100 mmol L^-1</sc> NaCl treated). The two germination indicators including the germination potential and the germination rate, as well as seven seedling indicators, including the relative chlorophyll content (SPAD), seedling length, root length, seedling fresh weight, seedling dry weight, root fresh weight, root dry weight were measured. The relative values of various indicators under salt stress were calculated, showing that the relative germination potential and relative germination rate of 110 sorghum landraces were 0<bold>–</bold>98.89% and 23.65<bold>%–</bold>101.79%, and The seven seedling indicators were 59.53%<bold>–</bold>99.91%, 52.47%<bold>–</bold>95.23%, 47.87%<bold>–</bold>100.14%, 27.43%<bold>–</bold>95.28%, 30.48%<bold>–</bold>98.26%, 21.62%<bold>–</bold>100.34%, 31.46%<bold>–</bold>102.13%, respectively. Combined the membership function value analysis, principal component analysis with cluster analysis, the salt tolephyll content (SPAD), seedling length, root length, seedling fresh weight, seedling dry weight, root fresh weight, root dry weight were measured. The relative values of various indicators under salt stress were calculated, showing that the relative germination potential and relative germination rate of 110 sorghum landraces were 0<bold>–</bold>98.89% and 23.65<bold>%–</bold>101.79%, and The seven seedling indicators were 59.53%<bold>–</bold>99.91%, 52.47%<bold>–</bold>95.23%, 47.87%<bold>–</bold>100.14%, 27.43%<bold>–</bold>95.28%, 30.48%<bold>–</bold>98.26%, 21.62%<bold>–</bold>100.34%, 31.46%<bold>–</bold>102.13%, respectively. Combined the membership function value analysis, principal component analysis with cluster analysis, the salt tolerance ability of the 110 landraces at germination stage and seedling stage was comprehensively evaluated and the 110 landraces were clustered into four groups. A batch of sorghum landraces with salt tolerance at germination and seedling stages were identified, especially ten landraces, including Chaoyangbangchui (00003011) from Inner Mongolia and the Baidazimao (00001081) from Beijing showed high salt tolerance, which can be used in further research. There was no significant correlation in salt toleghum landraces with salt tolerance at germination and seedling stages were identified, especially ten landraces, including Chaoyangbangchui (00003011) from Inner Mongolia and the Baidazimao (00001081) from Beijing showed high salt tolerance, which can be used in further research. There was no significant correlation in salt tolerance between the germination stage and the seedling stage. Principal component analysis results indicated that seedling dry weight and root fresh weight can be used as indicators for the evaluation of salt tolerance of a large number of sorghum landraces at seedling stage.

Characterization of the complete chloroplast genome of the Chinese sorghum, Sorghum bicolor from China

Chinese sorghum (Sorghum bicolor) is the most famous C4 plant and the most important cereal crops in the world. In this study, we obtained the complete chloroplast genome sequence of Chinese sorghum using BGISEQ-500 Sequencing Platform. Its chloroplast genome size has 141,266 bp, containing a large single copy region (83,406 bp), a small single copy region (13,712 bp), and a pair of IR regions (22,174 bp). The overall GC contents of the chloroplast genome were 38.5%. This circular genome contains 140 annotated genes, including 84 protein-coding genes, 48 tRNAs, and eight rRNAs. Further, the phylogenetic analysis using maximum likelihood (ML) method showed that Chinese sorghum has the closest phylogenetic relationship with Sorghum arundinaceum. This complete chloroplast genomes can be subsequently used for the genetic breeding and brewing industry.

Evaluation of Genetic Variation among Sorghum Varieties from Southwest China via Genome Resequencing.

Little is known regarding genomic variation among glutinous sorghum [ (L.) Moench] varieties grown in southwest China, which are primarily used to brew the popular Jiang-flavor liquor. This study evaluated genomic variation among six representative sorghum accessions via whole-genome resequencing. The evaluation revealed 2365,363 single-nucleotide polymorphisms (SNPs), 394,365 insertions and deletions, and 47,567 copy number variations among the six genomes. Chromosomes 5 and 10 showed relatively high SNP densities, whereas whole-genome diversity in this population was low. In addition, some chromosomal loci exhibited obvious selection during the breeding process. Sorghum accessions from southwest China formed an elite germplasm population compared with the findings of other geographic populations, and the elite variety 'Hongyingzi' contained 79 unique genes primarily involved in basic metabolism. The six sorghum lines contained a large number of high-confidence genes, with Hongyingzi in particular possessing 104 unique genes. These findings advance our understanding of domestication of the sorghum genome, and Chinese sorghum accessions will be valuable resources for further research and breeding improvements.

Field-based high-throughput phenotyping of plant height in sorghum using different sensing technologies

BackgroundPlant height is an important morphological and developmental phenotype that directly indicates overall plant growth and is widely predictive of final grain yield and biomass. Currently, manually measuring plant height is laborious and has become a bottleneck for genetics and breeding programs. The goal of this research was to evaluate the performance of five different sensing technologies for field-based high throughput plant phenotyping (HTPP) of sorghum [Sorghum bicolor (L.) Moench] height. With this purpose, (1) an ultrasonic sensor, (2) a LIDAR-Lite v2 sensor, (3) a Kinect v2 camera, (4) an imaging array of four high-resolution cameras were evaluated on a ground vehicle platform, and (5) a digital camera was evaluated on an unmanned aerial vehicle platform to obtain the performance baselines to measure the plant height in the field. Plot-level height was extracted by averaging different percentiles of elevation observations within each plot. Measurements were taken on 80 single-row plots of a US × Chinese sorghum recombinant inbred line population. The performance of each sensing technology was also qualitatively evaluated through comparison of device cost, measurement resolution, and ease and efficiency of data analysis.ResultsWe found the heights measured by the ultrasonic sensor, the LIDAR-Lite v2 sensor, the Kinect v2 camera, and the imaging array had high correlation with the manual measurements (r ≥ 0.90), while the heights measured by remote imaging had good, but relatively lower correlation to the manual measurements (r = 0.73).ConclusionThese results confirmed the ability of the proposed methodologies for accurate and efficient HTPP of plant height and can be extended to a range of crops. The evaluation approach discussed here can guide the field-based HTPP research in general.

Southern rice black-streaked dwarf virus: a white-backed planthopper-transmitted fijivirus threatening rice production in Asia

Southern rice black-streaked dwarf virus (SRBSDV), a non-enveloped icosahedral virus with a genome of 10 double-stranded RNA segments, is a novel species in the genus Fijivirus (family Reoviridae) first recognized in 2008. Rice plants infected with this virus exhibit symptoms similar to those caused by Rice black-streaked dwarf virus. Since 2009, the virus has rapidly spread and caused serious rice losses in East and Southeast Asia. Significant progress has been made in recent years in understanding this disease, especially about the functions of the viral genes, rice–virus–insect interactions, and epidemiology and control measures. The virus can be efficiently transmitted by the white-backed planthopper (WBPH, Sogatella furcifera) in a persistent circulative propagative manner but cannot be transmitted by the brown planthopper (Nilaparvata lugens) and small brown planthopper (Laodelphax striatellus). Rice, maize, Chinese sorghum (Coix lacryma-jobi) and other grass weeds can be infected via WBPH. However, only rice plays a major role in the virus infection cycle because of the vector’s preference. In Southeast Asia, WBPH is a long-distance migratory rice pest. The disease cycle can be described as follows: SRBSDV and its WBPH vector overwinter in warm tropical or sub-tropical areas; viruliferous WBPH adults carry the virus from south to north via long-distance migration in early spring, transmit the virus to rice seedlings in the newly colonized areas, and lay eggs on the infected seedlings; the next generation of WBPHs propagate on infected seedlings, become viruliferous, disperse, and cause new disease outbreaks. Several molecular and serological methods have been developed to detect SRBSDV in plant tissues and individual insects. Control measures based on protection from WBPH, including seedbed coverage, chemical seed treatments, and chemical spraying of seedlings, have proven effective in China.

Genetic Diversity in a Collection of Chinese Sorghum Landraces Assessed by Microsatellites

Genetic diversity was characterized in a collection of 159 sorghum (Sorghum bicolor L. Moench) landraces gathered from the colder region (primarily the northeastern region) of China. A set of 41 microsatellites or simple sequence repeat (SSR) markers distributed throughout the 10 chromosomes of sorghum was utilized in the analysis. Majority (40 out of 41 SSRs, 98%) of the SSR markers were polymorphic and highly informative with polymorphism information content (PIC) value ranging from 0.05 to 0.92. An estimation of genetic similarity coefficients (GSC, with values ranging from 0.42 to 0.96) revealed a range of variability in this collection of sorghum landraces. Eight clusters of accessions were identified at a cut off at 0.50 GSC and these groupings were supported by the analysis of subpopulations using Structure. This study provides evidence that Chinese landraces of sorghum exhibit moderate genetic diversity and results from cluster analysis may well aid in identification of diverse accessions that can serve as parental lines for efficient utilization and application of these germplasm into sorghum breeding programs.

Assessment of Genetic Diversity in Chinese Sorghum Landraces Using SSR Markers as Compared with Foreign Accessions

The genetic variation of 184 Chinese sorghum landraces(Sorghum bicolor L.) from a broad geographic area and representing different phenotypes,and 69 representative foreign cultivated sorghum accessions(world sorghum),was assessed using 32 nuclear SSR primer pairs.Overall,lower level of genetic diversity was detected in Chinese sorghum than in world sorghum.The allelic richness(Rs) and Nei's allele diversity(He) for Chinese sorghum and world sorghum were 9.81 and 0.629,and 11.52 and 0.745,respectively.Fewer unique alleles were detected in Chinese sorghum than in world sorghum.Chinese sorghum had a genetic diversity level lower than accessions from East Africa(He=0.732),North America(He=0.707) and South Asia(He=0.712);and was only comparable to those from South African accessions(He=0.609).Marked differences in level of genetic variation were revealed between Chinese sorghum landraces from 12 provinces,with Rs ranging from 3.64 to 4.88 and He from 0.517 to 0.714.Accessions from Jilin Province exhibited the highest level of genetic diversity among all regions in China,which was comparable to the sorghum in East Africa.The results indicated a strong divergence of Chinese sorghum from world sorghum,but a weak differentiation among Chinese sorghum both on regional and type bases.Principal component analysis(PCA) clearly separated Chinese sorghum from world accessions but could not separate Chinese sorghum into discrete geographical or phenotypic groups.Analysis of molecular variance(AMOVA) indicated that 20.43% of the total genetic variation was attributable to the difference between world and Chinese sorghum and 79.57% occurred among Chinese and world sorghum accessions.For Chinese sorghum,partitioning the total variation revealed that genetic diversity mainly existed among accessions within regions(91.94%) or eco-regions(94.97%) rather than among regions(8.06%) or eco-regions(5.03%).Similarly,a large portion(97.93%) of the total variation was found within types compared to among types(2.07%).Our study supports the view that Chinese sorghum is of African origin.Chinese sorghum may have experienced a long history of natural and human selection when largely isolated from outside world since prehistoric time.Suggestions for sorghum breeding programs were presented in the light of these data.

Genetic diversity in Chinese sorghum landraces revealed by chloroplast simple sequence repeats

A collection of sorghum, including more than 12,000 Chinese landraces, has been constructed and maintained in China. However, the genetic diversity of Chinese sorghum landraces has not been fully investigated, and the origin of Chinese sorghum is still in dispute. In this study, the complete chloroplast genome sequence of sorghum line Tx623B was searched for simple sequence repeats (SSRs). 31 SSR loci with at least 10 mononucleotide repeats or five dinucleotide repeats were identified, and primer pairs for 27 loci were designed. Chloroplast DNA variation in cultivated sorghum was investigated by using these primer pairs on 185 Chinese sorghum landraces and 70 cultivated sorghum accessions from other countries. Among the 27 loci, 14 were polymorphic. The number of alleles per polymorphic locus ranged from 2 to 5 with an average of 2.79. Allelic data at 14 polymorphic loci were combined to give 12 haplotypes. The average allelic diversity index across the 14 polymorphic loci and corresponding haplotype diversity were markedly lower for Chinese sorghum landraces than were those for accessions from other countries. However, Chinese sorghum landraces shared a predominant allele at each polymorphic locus and a predominant haplotype with foreign accessions. Our results indicate that Chinese landraces experienced a severe maternal bottleneck during the introduction process with a predominant haplotype being present in 171 of 185 accessions analyzed. Except for one rare exception, haplotypes found in Chinese landraces were either identical or closely related to those found in foreign accessions and could not be separated clearly from them by cluster analysis. Our results are consistent with the hypothesis of African origin of Chinese sorghum.

Evaluation of Sorghum Germplasm from China against Claviceps africana, Causal Agent of Sorghum Ergot

Forty Chinese sorghum landraces maintained by the USDA-ARS Plant Genetic Resources Conservation Unit, Griffin, GA were evaluated for ergot resistance at the Texas A&amp;M Research Farm, College Station, Texas, during the 2005 and 2006 growing seasons. The male sterile line, ATx623, was included as a susceptible control and three IS8525 derived lines were included as resistant controls. The disease infection level was low in the susceptible check in 2005 due to unfavorable environmental conditions, but the majority of the Chinese accessions showed a higher level of tolerance than the resistant controls and in contrast, infection severity was high in 2006. The IS8525 resistant controls averaged 25% infection compared to an average infection of 18% for the 40 Chinese accessions. Four Chinese accessions, PI63923, PI511832, PI610749, and PI610688, recorded less than 10% ergot infection and thus, these four accessions may possess genes for ergot resistance. Further research is underway to evaluate these accessions under multi-environments to confirm resistance and to determine if the resistance is associated with pollination characteristics. Accepted for publication 19 February 2008. Published 19 May 2008.

A Comparison of U.S. and Chinese Sorghum Germplasm for Early Season Cold Tolerance

ABSTRACTEarly season cold tolerance in grain sorghum [Sorghum bicolor (L.) Moench] is a desirable trait for extending its production range and minimizing risks associated with early spring plantings. Ten Chinese Kaoliang accessions were compared with 10 U.S. inbred parental lines and 10 U.S. commercial hybrids for a range of cold tolerance traits under laboratory, growth chamber, and field settings. Chinese lines were superior to both the inbred and hybrid classes in laboratory germination rates and field‐based rates of emergence. In the growth chamber assays, Kaoliangs were not significantly different than U.S. hybrids for most traits measured at either of the two temperature treatments (12 and 24°C), with the exception of shoot length, for which the Chinese germplasm was higher. At the cooler temperature, Kaoliangs were significantly greater than U.S. inbreds for only fresh shoot weight; when tested at the warmer temperature, Kaoliangs had higher dry root weight, fresh and dry shoot weights, and fresh and dry whole plant weights, relative to the U.S. inbred class. The U.S. hybrids had greater total plot weight and final stand counts in the field than Kaoliangs, which were likewise higher than U.S. inbreds for both of these traits. Chinese accessions from this working group would serve as a source of favorable genes primarily for tolerance to low temperatures during the germination and emergence phase of growth in the breeding of cold tolerance sorghum lines.

Chinese sorghum genetic resources

In its long period of evolution and cultivation, Chinese sorghums have formed a rich genetic base in which unique characteristics have evolved. These resources and their characteristics have been identified and partially utilized within China’s breeding programs. Records and data have been compiled and updated into theAnnuals of Chinese Sorghum Varieties, Catalogue of Chinese Sorghum Variety Resources. These evaluations and recorded information provide a solid base from which further studies and utilization of this important source of genetic diversity can take place in the future.

Starch Properties of Barnard Red, a South African Red Sorghum Variety of Significance in Traditional African Brewing

Starch was isolated from Barnard Red (a South African sorghum variety) and a Chinese sorghum sample. Starch and flour properties (gelatinization, pasting, and gel texture) were compared with those of a standard corn starch. Significant findings were: 1. Barnard Red starch had lower gelatinization temperature than either Chinese sorghum or corn starch; 2. starch gels of corn and Barnard Red were of similar hardness; 3. Barnard Red starch pastes had very high viscosity compared to corn and Chinese sorghum; 4. Barnard Red starch shear-thinned more than its flour paste in the absence of amylase activity.

Genetic contribution of Chinese landraces to the development of sorghum hybrids

The origin of sorghum hybrids developed in China in the past several decades was analyzed in order to assess genetic contribution of Chinese landraces (Kaoliang) to the sorghum hybrids, to evaluate the genetic diversity existing in the A-lines and R-lines mainly used in breeding programs, and to outline a proper strategy for the future development of sorghum improvement. Basically, Chinese sorghum landraces have played an important role in the development of R-lines while foreign germplasm have played an essential role in the development of A-lines. Because cytoplasmic male-sterility has not been certainly found in Chinese sorghum, cytoplasmic and nuclear genetic backgrounds of A-lines will continue to depend on foreign sorghum types in the future. Genetic diversification including cytoplasmic diversification has to be a priority in future hybrid breeding and production. To obtain superior hybrid vigor, Chinese sorghum germplasm will have to play a more important role in hybrid breeding programs in the future.