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Anthracnose and grain mold are two of the most significant diseases of sorghum, a versatile crop that plays an important part in the daily lives of millions of inhabitants, especially in the drier tropical regions. The aim of this study was to determine the influence of four agronomic traits in selected sorghum germplasms on the two diseases using Spearman's ρ test to identify significant pairwise correlations. Both anthracnose and grain mold scores were significantly and negatively correlated with seed weight and germination rate. The grain mold infection score also demonstrated negative correlations with plant height (Spearman ρ = −0.61 and p-value = <0.0001) and panicle length (Spearman ρ = −0.27 and p-value = 0.0022). In this investigation, principal component analysis and clustering variables analysis revealed that seed weight and germination rate exhibited a directional alignment, suggesting a positive association. Similarly, panicle length and plant height clustered together, suggesting a shared variation pattern. Additionally, a support vector machine and random forest models effectively predicted the germination rate based on the studied traits, highlighting the potential of machine learning in understanding complex trait relationships in sorghum. This work provides insights into the relationship between agronomic traits and disease resistance, thus contributing to sorghum improvement efforts. [ABSTRACT FROM AUTHOR]

Sorghum is a climate-resilient cereal and staple food crop for more than 200 million people in arid and semi-arid countries of Asia and Africa. Despite the economic importance, the productivity of sorghum in India is constrained by biotic and abiotic stresses such as incidences of shoot fly, grain mold and drought. Indian sorghum breeding focused on dual-purpose (grain and fodder), short-duration varieties with multiple resistance/tolerance to pests and diseases and improved nutritional quality (high protein, iron and zinc and low fat). In this context, it is important to ascertain the genetic progress made over 30 years by assessing the efficiency of past achievements in genetic yield potential and to facilitate future genetic improvement. The current study determined the genetic gain in 24 sorghum varieties developed by the national and state level research systems during 1990-2020. The 24 varieties were evaluated for three years (2018-2020) at six locations in Telangana state for yield, nutritional characteristics and tolerance to shoot fly and grain mold. The absolute grain yield genetic gain from the base year 1990 is 44.93 kg/ha/yr over the first released variety CSV 15. The realized mean yield increased from 2658 kg/ha of the variety CSV 15 in 1990s to 4069 kg/ha of SPV 2579 developed in 2020s. The absolute genetic gain for grain mold resistance is -0.11 per year with an overall relative gain of 1.46% over CSV 15. The top varieties for grain yield (SPV 2579, SPV 2678 and SPV 2578), fodder yield (PYPS 2, SPV 2769 and SPV 2679), shoot fly tolerance (PYPS 8, PYPS 2 and SPV 2179), mold tolerance (PYPS 8, PYPS 2 and SPV 2579) and high protein (PYPS 8, PYPS 2 and SPV 2769) were identified for possible scale up and further use in breeding program diversification. The study revealed that sorghum varieties bred with diverse genetic backgrounds such as landraces and with tolerance to pests and diseases had stable yield performance. Application of genomics and other precision tools can double genetic gains for these traits to strengthen sorghum cultivation in rainfed areas serving food and nutrition security. [ABSTRACT FROM AUTHOR]

Sorghum is a climate-resilient cereal and staple food crop for more than 200 million people in arid and semi-arid countries of Asia and Africa. Despite the economic importance, the productivity of sorghum in India is constrained by biotic and abiotic stresses such as incidences of shoot fly, grain mold and drought. Indian sorghum breeding focused on dual-purpose (grain and fodder), short-duration varieties with multiple resistance/tolerance to pests and diseases and improved nutritional quality (high protein, iron and zinc and low fat). In this context, it is important to ascertain the genetic progress made over 30 years by assessing the efficiency of past achievements in genetic yield potential and to facilitate future genetic improvement. The current study determined the genetic gain in 24 sorghum varieties developed by the national and state level research systems during 1990-2020. The 24 varieties were evaluated for three years (2018-2020) at six locations in Telangana state for yield, nutritional characteristics and tolerance to shoot fly and grain mold. The absolute grain yield genetic gain from the base year 1990 is 44.93 kg/ha/yr over the first released variety CSV 15. The realized mean yield increased from 2658 kg/ha of the variety CSV 15 in 1990s to 4069 kg/ha of SPV 2579 developed in 2020s. The absolute genetic gain for grain mold resistance is -0.11 per year with an overall relative gain of 1.46% over CSV 15. The top varieties for grain yield (SPV 2579, SPV 2678 and SPV 2578), fodder yield (PYPS 2, SPV 2769 and SPV 2679), shoot fly tolerance (PYPS 8, PYPS 2 and SPV 2179), mold tolerance (PYPS 8, PYPS 2 and SPV 2579) and high protein (PYPS 8, PYPS 2 and SPV 2769) were identified for possible scale up and further use in breeding program diversification. The study revealed that sorghum varieties bred with diverse genetic backgrounds such as landraces and with tolerance to pests and diseases had stable yield performance. Application of genomics and other precision tools can double genetic gains for these traits to strengthen sorghum cultivation in rainfed areas serving food and nutrition security.

Sorghum is a major grain crop used in traditional meals and health drinks, and as an efficient fuel. However, its productivity, value, germination, and usability are affected by grain mold, which is a severe problem in sorghum production systems, which reduces the yield of harvested grains for consumer use. The organic approach to the management of the disease is essential and will increase consumer demand. Bioactive molecules like mVOC (volatile organic compound) identification are used to unravel the molecules responsible for antifungal activity. The Streptomyces rochei strain (ASH) has been reported to be a potential antagonist to many pathogens, with high levels of VOCs. The present study aimed to study the inhibitory effect of S. rochei on sorghum grain mold pathogens using a dual culture technique and via the production of microbial volatile organic compounds (mVOCs). mVOCs inhibited the mycelial growth of Fusarium moniliforme by 63.75 and Curvularia lunata by 68.52%. mVOCs suppressed mycelial growth and inhibited the production of spores by altering the structure of mycelia in tripartite plate assay. About 45 mVOCs were profiled when Streptomyces rochei interacted with these two pathogens. In the present study, several compounds were upregulated or downregulated by S. rochei, including 2-methyl-1-butanol, methanoazulene, and cedrene. S. rochei emitted novel terpenoid compounds with peak areas, such as myrcene (1.14%), cymene (6.41%), and ç-terpinene (7.32%) upon interaction with F. moniliforme and C. lunata. The peak area of some of the compounds, including furan 2-methyl (0.70%), benzene (1.84%), 1-butanol, 2-methyl-(8.25%), and myrcene (1.12)%, was increased during tripartite interaction with F. moniliforme and C. lunata, which resulted in furan 2-methyl (6.60%), benzene (4.43%), butanol, 2-methyl (18.67%), and myrcene (1.14%). These metabolites were implicated in the sesquiterpenoid and alkane biosynthetic pathways and the oxalic acid degradation pathway. The present study shows how S. rochei exhibits hyperparasitism, competition, and antibiosis via mVOCs. In addition to their antimicrobial functions, these metabolites could also enhance plant growth. [ABSTRACT FROM AUTHOR]

Mold growth reduces the quality of stored grains, besides producing toxins that pose a potential threat to human health. Therefore, prevention of grain mold growth during storage is important to ensure a safe and high‐quality product, preferably using an eco‐friendly antifungal agent. The puroindoline (PIN) protein was extracted by Triton X‐114 and identified by QE mass spectrometry. Aspergillus flavus has attracted much attention because of its toxic secondary metabolites, and PIN protein showed a significant inhibition on A. flavus growth. Scanning electron microscopy revealed altered spore morphology of A. flavus following PIN protein treatment, and propidium iodide staining showed incomplete spore cell membranes. The disruption and deformation of A. flavus spores suggest that the cell walls and cell membranes were compromised. Decreased mitochondrial membrane potential and increased levels of intracellular reactive oxygen specieswere detected using JC‐1 and 2,7‐dichlorodihydrofluorescein diacetate staining, respectively. PIN protein could effectively inhibit the growth and aflatoxins B1 production of A. flavus in stored grains, such as wheat and rice. PIN proteins can inhibit the growth of many common grain storage molds, including Penicillium, Aspergillus spp. (A. flavus, A. glaucus, A. kawachii, A. ochraceus and A. niger), Alternaria and Fusarium graminearum, in a dose‐dependent manner. PIN protein has a significant inhibitory effect on the growth of grain molds, with a stronger inhibitory effect noted in wheat and rice. Our study provides a novel and simple theoretical basis for the selection and storage of mold resistance in grains and food during storage. [ABSTRACT FROM AUTHOR]

Abstract Background Sorghum grain mold is the most important disease of the crop. The disease results from simultaneous infection of the grain by multiple fungal species. Host responses to these fungi and the underlying molecular and cellular processes are poorly understood. To understand the genetic, molecular and biochemical components of grain mold resistance, transcriptome profiles of the developing grain of resistant and susceptible sorghum genotypes were studied. Results The developing kernels of grain mold resistant RTx2911 and susceptible RTx430 sorghum genotypes were inoculated with a mixture of fungal pathogens mimicking the species complexity of the disease under natural infestation. Global transcriptome changes corresponding to multiple molecular and cellular processes, and biological functions including defense, secondary metabolism, and flavonoid biosynthesis were observed with differential regulation in the two genotypes. Genes encoding pattern recognition receptors (PRRs), regulators of growth and defense homeostasis, antimicrobial peptides, pathogenesis-related proteins, zein seed storage proteins, and phytoalexins showed increased expression correlating with resistance. Notably, SbLYK5 gene encoding an orthologue of chitin PRR, defensin genes SbDFN7.1 and SbDFN7.2 exhibited higher expression in the resistant genotype. The SbDFN7.1 and SbDFN7.2 genes are tightly linked and transcribed in opposite orientation with a likely common bidirectional promoter. Interestingly, increased expression of JAZ and other transcriptional repressors were observed that suggested the tight regulation of plant defense and growth. The data suggest a pathogen inducible defense system in the developing grain of sorghum that involves the chitin PRR, MAPKs, key transcription factors, downstream components regulating immune gene expression and accumulation of defense molecules. We propose a model through which the biosynthesis of 3-deoxyanthocynidin phytoalexins, defensins, PR proteins, other antimicrobial peptides, and defense suppressing proteins are regulated by a pathogen inducible defense system in the developing grain. Conclusions The transcriptome data from a rarely studied tissue shed light into genetic, molecular, and biochemical components of disease resistance and suggested that the developing grain shares conserved immune response mechanisms but also components uniquely enriched in the grain. Resistance was associated with increased expression of genes encoding regulatory factors, novel grain specific antimicrobial peptides including defensins and storage proteins that are potential targets for crop improvement.

Sorghum is a major grain crop used in traditional meals and health drinks, and as an efficient fuel. However, its productivity, value, germination, and usability are affected by grain mold, which is a severe problem in sorghum production systems, which reduces the yield of harvested grains for consumer use. The organic approach to the management of the disease is essential and will increase consumer demand. Bioactive molecules like mVOC (volatile organic compound) identification are used to unravel the molecules responsible for antifungal activity. The Streptomyces rochei strain (ASH) has been reported to be a potential antagonist to many pathogens, with high levels of VOCs. The present study aimed to study the inhibitory effect of S. rochei on sorghum grain mold pathogens using a dual culture technique and via the production of microbial volatile organic compounds (mVOCs). mVOCs inhibited the mycelial growth of Fusarium moniliforme by 63.75 and Curvularia lunata by 68.52%. mVOCs suppressed mycelial growth and inhibited the production of spores by altering the structure of mycelia in tripartite plate assay. About 45 mVOCs were profiled when Streptomyces rochei interacted with these two pathogens. In the present study, several compounds were upregulated or downregulated by S. rochei, including 2-methyl-1-butanol, methanoazulene, and cedrene. S. rochei emitted novel terpenoid compounds with peak areas, such as myrcene (1.14%), cymene (6.41%), and ç-terpinene (7.32%) upon interaction with F. moniliforme and C. lunata. The peak area of some of the compounds, including furan 2-methyl (0.70%), benzene (1.84%), 1-butanol, 2-methyl-(8.25%), and myrcene (1.12)%, was increased during tripartite interaction with F. moniliforme and C. lunata, which resulted in furan 2-methyl (6.60%), benzene (4.43%), butanol, 2-methyl (18.67%), and myrcene (1.14%). These metabolites were implicated in the sesquiterpenoid and alkane biosynthetic pathways and the oxalic acid degradation pathway. The present study shows how S. rochei exhibits hyperparasitism, competition, and antibiosis via mVOCs. In addition to their antimicrobial functions, these metabolites could also enhance plant growth.

Increasing sorghum production per unit area in the farmer's field by developing high yielding tannin-free and grain mold tolerant varieties in Senegal is the goal of the present study. Line × tester mating design was used to cross eleven tannin-free non-photoperiodic male fertile sorghum varieties with two male-sterile A-lines to produce 22 F1 hybrids. These hybrids along with the thirteen parents and one grain mold resistant hybrid check were evaluated under natural grain mold infestation in two contrasted sites using a 6 × 6 lattice design with three replications. Results on combining ability suggested that additive gene actions were important in the control of grain mold resistance while non-additive gene actions were preponderant in the inheritance of grain yield. The parental lines F2-20, Macia, Faourou, and Dorado were the best general combiner for grain mold resistance. Of these, Dorado was identified as the best combiner for yield and yield components. Additionally, the hybrid CE310-31A × Sureño was identified as the best hybrids combination for yield, yield components and grain mold resistance. Furthermore, the hybrid crosses CE310-31A × F2-20, CE310-31A × Sureño and AVG-1 × Dorado showed the best mid-parent heterosis for grain yield and resistance to grain mold. Moreover, based on their combining ability and heterosis, seven hybrids were identified for their resistance to grain mold and high yielding. These hybrids could be tested in multi-location trials for a subsequent release. [ABSTRACT FROM AUTHOR]

Sorghum is the fifth most important cereal worldwide, spreading from Africa throughout the world. It is particularly important in the semi-arid tropics due to its drought tolerance, and when cultivated in Southeast Asia commonly occurs as a second crop during the dry season. We recovered Fusarium from sorghum in Thailand and found F. proliferatum, F. thapsinum and F. verticillioides most frequently, and intermittent isolates of F. sacchari and F. beomiforme. The relatively high frequencies of F. proliferatum and F. verticillioides, suggest mycotoxin contamination, particularly fumonisins and moniliformin, should be evaluated. Genetic variation within the three commonly recovered species was characterized with vegetative compatibility, mating type, Amplified Fragment Length Polymorphisms (AFLPs), and female fertility. Effective population number (Ne) was highest for F. verticillioides and lowest for F. thapsinum with values based on mating type allele frequencies higher than those based on female fertility. Based on AFLP genetic variation, the F. thapsinum populations were the most closely related, the F. verticillioides populations were the most distantly related, and the F. proliferatum populations were in an intermediate position. The genetic variation observed could result if F. thapsinum is introduced primarily with seed, while F. proliferatum and F. verticillioides could arrive with seed or be carried over from previous crops, e.g., rice or maize, which sorghum is following. Confirmation of species transmission patterns is needed to understand the agricultural systems in which sorghum is grown in Southeast Asia, which are quite different from the systems found in Africa, Australia, India and the Americas.

The infection caused by grain mold in rainy season grown sorghum deteriorates the physical and chemical quality of the grain, which causes a reduction in grain size, blackening, and making them unfit for human consumption. Therefore, the breeding for grain mold resistance has become a necessity. Pedigree breeding has been widely used across the globe to tackle the problem of grain mold. In the present study, a population breeding approach was employed to develop genotypes resistant to grain mold. The complex genotype × environment interactions (GEIs) make the task of identifying stable grain mold-resistant lines with good grain yield (GY) challenging. In this study, the performance of the 33 population breeding derivatives selected from the four-location evaluation of 150 genotypes in 2017 was in turn evaluated over four locations during the rainy season of 2018. The Genotype plus genotype-by-environment interaction (GGE) biplot analysis was used to analyze a significant GEI observed for GY, grain mold resistance, and all other associated traits. For GY, the location explained a higher proportion of variation (51.7%) while genotype (G) × location (L) contributed to 21.9% and the genotype contributed to 11.2% of the total variation. For grain mold resistance, G × L contributed to a higher proportion of variation (30.7%). A graphical biplot approach helped in identifying promising genotypes for GY and grain mold resistance. Among the test locations, Dharwad was an ideal location for both GY and grain mold resistance. The test locations were partitioned into three clusters for GY and two clusters for grain mold resistance through a “which-won-where” study. Best genotypes in each of these clusters were selected. The breeding for a specific cluster is suggested. Genotype-by-trait biplots indicated that GY is influenced by flowering time, 100-grain weight (HGW), and plant height (PH), whereas grain mold resistance is influenced by glume coverage and PH. Because GY and grain mold score were independent of each other, there is a scope to improve both yield and resistance together.

Intermittent drought and an incidence of grain mold disease are the two major constraints affecting sorghum production and productivity. The study aimed at developing drought-tolerant sorghum varieties possessing a high protein content and tolerance to grain mold with stable performance using additive main effects and multiplicative interaction (AMMI) and genotype and genotype × environment interaction (GGE) biplot methods. Systematic hybridization among the 11 superior landraces resulted in subsequent pedigree-based breeding and selection from 2010 to 2015 evolved 19 promising varieties of grains such as white, yellow, and brown pericarp grains. These grain varieties were evaluated for their adaptability and stability for yield in 13 rainfed environments and for possessing tolerance to grain mold in three hot spot environments. A variety of yellow pericarp sorghum PYPS 2 (3,698 kg/ha; 14.52% protein; 10.70 mg/100 g Fe) possessing tolerance to grain mold was identified as a stable variety by using both AMMI and GGE analyses. Four mega-environments were identified for grain yield and fodder yield. Sorghum varieties PYPS 2, PYPS 4, PYPS 8, and PYPS 11 were highly stable in E2 with a low grain mold incidence. Besides meeting the nutritional demand of smallholder farmers under dryland conditions, these varieties are suitable for enhancing sorghum productivity under the present climate change scenario.

The infection caused by grain mold in rainy season grown sorghum deteriorates the physical and chemical quality of the grain, which causes a reduction in grain size, blackening, and making them unfit for human consumption. Therefore, the breeding for grain mold resistance has become a necessity. Pedigree breeding has been widely used across the globe to tackle the problem of grain mold. In the present study, a population breeding approach was employed to develop genotypes resistant to grain mold. The complex genotype × environment interactions (GEIs) make the task of identifying stable grain mold-resistant lines with good grain yield (GY) challenging. In this study, the performance of the 33 population breeding derivatives selected from the four-location evaluation of 150 genotypes in 2017 was in turn evaluated over four locations during the rainy season of 2018. The Genotype plus genotype-by-environment interaction (GGE) biplot analysis was used to analyze a significant GEI observed for GY, grain mold resistance, and all other associated traits. For GY, the location explained a higher proportion of variation (51.7%) while genotype (G) × location (L) contributed to 21.9% and the genotype contributed to 11.2% of the total variation. For grain mold resistance, G × L contributed to a higher proportion of variation (30.7%). A graphical biplot approach helped in identifying promising genotypes for GY and grain mold resistance. Among the test locations, Dharwad was an ideal location for both GY and grain mold resistance. The test locations were partitioned into three clusters for GY and two clusters for grain mold resistance through a "which-won-where" study. Best genotypes in each of these clusters were selected. The breeding for a specific cluster is suggested. Genotype-by-trait biplots indicated that GY is influenced by flowering time, 100-grain weight (HGW), and plant height (PH), whereas grain mold resistance is influenced by glume coverage and PH. Because GY and grain mold score were independent of each other, there is a scope to improve both yield and resistance together. [ABSTRACT FROM AUTHOR]

Intermittent drought and an incidence of grain mold disease are the two major constraints affecting sorghum production and productivity. The study aimed at developing drought-tolerant sorghum varieties possessing a high protein content and tolerance to grain mold with stable performance using additive main effects and multiplicative interaction (AMMI) and genotype and genotype × environment interaction (GGE) biplot methods. Systematic hybridization among the 11 superior landraces resulted in subsequent pedigree-based breeding and selection from 2010 to 2015 evolved 19 promising varieties of grains such as white, yellow, and brown pericarp grains. These grain varieties were evaluated for their adaptability and stability for yield in 13 rainfed environments and for possessing tolerance to grain mold in three hot spot environments. A variety of yellow pericarp sorghum PYPS 2 (3,698 kg/ha; 14.52% protein; 10.70 mg/100 g Fe) possessing tolerance to grain mold was identified as a stable variety by using both AMMI and GGE analyses. Four mega-environments were identified for grain yield and fodder yield. Sorghum varieties PYPS 2, PYPS 4, PYPS 8, and PYPS 11 were highly stable in E2 with a low grain mold incidence. Besides meeting the nutritional demand of smallholder farmers under dryland conditions, these varieties are suitable for enhancing sorghum productivity under the present climate change scenario. [ABSTRACT FROM AUTHOR]

Background: Sorghum grain mold is the most important disease of the crop. The disease results from simultaneous infection of the grain by multiple fungal species. Host responses to these fungi and the underlying molecular and cellular processes are poorly understood. To understand the genetic, molecular and biochemical components of grain mold resistance, transcriptome profiles of the developing grain of resistant and susceptible sorghum genotypes were studied. Results: The developing kernels of grain mold resistant RTx2911 and susceptible RTx430 sorghum genotypes were inoculated with a mixture of fungal pathogens mimicking the species complexity of the disease under natural infestation. Global transcriptome changes corresponding to multiple molecular and cellular processes, and biological functions including defense, secondary metabolism, and flavonoid biosynthesis were observed with differential regulation in the two genotypes. Genes encoding pattern recognition receptors (PRRs), regulators of growth and defense homeostasis, antimicrobial peptides, pathogenesis-related proteins, zein seed storage proteins, and phytoalexins showed increased expression correlating with resistance. Notably, SbLYK5 gene encoding an orthologue of chitin PRR, defensin genes SbDFN7.1 and SbDFN7.2 exhibited higher expression in the resistant genotype. The SbDFN7.1 and SbDFN7.2 genes are tightly linked and transcribed in opposite orientation with a likely common bidirectional promoter. Interestingly, increased expression of JAZ and other transcriptional repressors were observed that suggested the tight regulation of plant defense and growth. The data suggest a pathogen inducible defense system in the developing grain of sorghum that involves the chitin PRR, MAPKs, key transcription factors, downstream components regulating immune gene expression and accumulation of defense molecules. We propose a model through which the biosynthesis of 3-deoxyanthocynidin phytoalexins, defensins, PR proteins, other antimicrobial peptides, and defense suppressing proteins are regulated by a pathogen inducible defense system in the developing grain. Conclusions: The transcriptome data from a rarely studied tissue shed light into genetic, molecular, and biochemical components of disease resistance and suggested that the developing grain shares conserved immune response mechanisms but also components uniquely enriched in the grain. Resistance was associated with increased expression of genes encoding regulatory factors, novel grain specific antimicrobial peptides including defensins and storage proteins that are potential targets for crop improvement. [ABSTRACT FROM AUTHOR]

Miridae is the largest Heteroptera family, with a tremendous worldwide economic impact, both as pests and natural enemies. Unlike most Hemiptera, herbivorous and omnivorous mirid bugs are lacerate/macerate and flush feeders, not phloem feeders. Plant responses to damage by arthropods of this feeding guild therefore occur via jasmonic acid or ethylene signaling pathways rather than the salicylic acid pathway. Moreover, unlike most other Heteroptera that lay eggs on the plant surface, mirids insert their eggs in plant tissues, resulting in oviposition injury. Similarly, regarding phytopathogenic fungi and oomycetes, a distinction should be made between biotrophic fungi (triggering the salicylic acid pathway plant response), and necrotrophic and/or hemibiotrophic fungi or oomycetes (triggering jasmonic acid or ethylene pathway plant responses). In that respect, phytopathogenic fungi or oomycetes (PFO) differ from phytopathogenic viruses and bacteria, the former being all biotrophic while the latter are theoretically hemibiotrophic. Here, for the first time, we review tripartite interactions between mirids, PFO, and crop plants. The major deliverables are as follows: Five major interaction frameworks are identified: (i) crop plant infection by PFO mechanically facilitated by prior mirid infestation; (ii) crop plant infection by PFO hampered by prior mirid infestation via crop plant signaling; (iii) crop plant infestation by mirids facilitated by prior PFO infection via crop plant signaling; (iv) crop plant infestation by mirids hampered by prior PFO infection via crop plant signaling; (v) crop plant infestation by mirids and/or infection by PFO hampered by prior mirid infestation and/or PFO infection via crop plant resource quality alteration. PFO and mirids may also occur concomitantly, favored by the same conditions, i.e., climatic or linked to endogeneous factors (e.g., redox status) in crop plant. Instances from each framework are described, and highlighted interactions are examined in view of managing mirid–PFO complexes on crop plants. [ABSTRACT FROM AUTHOR]

Abstract Grain mold, caused by a consortium of pathogenic fungal species, is the most important disease of sorghum [ Sorghum bicolor (L.) Moench]. Genome wide association study on 1425 diverse Ethiopian sorghum landraces identified a major grain mold resistance locus containing tightly linked and sequence related MYB transcription factor genes. The locus contains YELLOW SEED1 (Y1), a likely non-functional pseudo gene (Y2), and YELLOW SEED3 (Y3). SNPs and other sequence polymorphisms that alter the Y1 and Y3 genes correlated with susceptibility to grain mold and provided a strong genetic evidence. Accordingly, the expression of both Y1 and Y3 genes in the developing grain and glumes of a widely known susceptible sorghum line, RTx430, were severely reduced but significantly increased in the resistant line, RTx2911. In addition, the expression of flavonoid biosynthesis genes such as DIHYDROFLAVONOL 4-REDUCTASE 3 (DFR3) was significantly induced in the resistant line in response to inoculation by a mixture of spores from different molding fungi while the susceptible line displayed reduced expression. The data suggest that the MYB genes and their grain and glume specific expressions may determine the differential regulation of the flavonoid biosynthesis pathway genes, the synthesis of 3-Deoxyanthocynidins and ultimately responses to molding fungi. The study also suggested that resistance to grain mold may be negatively associated with grain functionality traits such as ' injera ' making quality of sorghum. Highlights • Grain mold resistance locus containing MYB transcription factor genes identified. • The locus regulates responses to molding fungi in the developing sorghum grain. • The locus contains a MYB gene, YELLOW SEED3 previously not described. • YELLOW SEED3 may be involved in synthesis of 3-Deoxyanthocyanins phytoalexins. • Grain mold resistance may be negatively associated with grain functionality traits. [ABSTRACT FROM AUTHOR]

The present investigation was carried out to estimate the nature and magnitude of genetic variability for yield and grain moldresistance in 99 sorghum F3 progenies of red × red and red × white crosses including parents and checks. Variation for grain moldassociated traits was analyzed with respect to grain hardness, panicle compactness, grain colour, glume length and glume colour.Among 99 F3 progenies 30 progenies exhibited partly hard grains and 19 progenies had hard grains and which exhibited lowincidence of grain mold. In case of panicle compactness, 6 progenies had very loose, 9 progenies had loose and 26 progenies hadsemi-loose panicles and exhibited low incidence of grain mold. Twenty one progenies and seven progenies had long glumecoverage and very long glume coverage respectively and these were resistant to grain mold. All the red grain coloured progeniesshowed low incidence of grain mold and progenies which had red and black coloured glumes were moderately resistant.Genotypes with hard grains, loose panicles, medium to long glume coverage and red and black coloured glumes had lowincidence of grain mold. First and eleventh F3 progenies of IS 24995 × IS 23585, first and ninth progeny of IS 24996 × IS 23585and 8th progeny of IS 25022 × IS 23585 were high yielding and resistant to grain mold.

In all sorghum (Sorghum bicolor (L.) Moench) production systems, grain molds can reduce the yield and quality of short duration cultivars if they mature in wet and humid weather. This investigation was taken up to find out combining ability for grain mold resistance under 4 environmental conditions by studying 168 hybrids and their parents along with checks. The pooled analysis of variance for combining ability revealed significant differences due to environments, parents, hybrids and various interactions indicating the existence of wide variability in the material under study. The ratios of additive to dominance variances revealed that additive gene action was predominant for inheritance of grain mold resistance (Panicle Grain Mold Rating - PGMR). Among the parents, two A-lines ICSA 369 and ICSA 370 and six testers viz., IS 41675, ICSR 91011, ICSR 89058, PVK 801, GD 65028, GD 65055 in all the 4 environments were identified as a good general combiners for grain mold resistance. These parents can be utilized for the development of grain mold resistant hybrids. [ABSTRACT FROM AUTHOR]

Rice contaminated with fungal species during storage is not only of poor quality and low economic value, but may also have harmful effects on human and animal health. The predominant fungal species isolated from rice grains during storage belong to the genera Aspergillus and Penicillium. Some of these fungal species produce mycotoxins; they are responsible for adverse health effects in humans and animals, particularly Aspergillus flavus, which produces the extremely carcinogenic aflatoxins. Not surprisingly, there have been numerous attempts to devise safety procedure for the control of such harmful fungi and production of mycotoxins, including aflatoxins. This review provides information about fungal and mycotoxin contamination of stored rice grains, and microbe-based (biological) strategies to control grain fungi and mycotoxins. The latter will include information regarding attempts undertaken for mycotoxin (especially aflatoxin) bio-detoxification and microbial interference with the aflatoxin-biosynthetic pathway in the toxin-producing fungi. [ABSTRACT FROM AUTHOR]

Sorghum is an important worldwide crop whose yield can be significantly reduced by anthracnose ( Colletotrichum sublineola ) and grain mold diseases (multiple fungi). The identification of new genetic sources of resistance to both diseases is imperative for the development of new sorghum varieties. To this end, a total of 80 exotic germplasm accessions from Burkina Faso (BFA) and South Africa (ZAF) were evaluated for anthracnose and grain mold resistance during two planting periods in 2012 at the USDA-ARS experimental farms in Isabela, Puerto Rico. Twelve accessions were resistant to anthracnose during both evaluations of which 10 are originally from BFA. The anthracnose resistant accessions identified herein had a hypersensitive reaction characterized by lesions having red and purple color. Likewise, 9 accessions exhibited grain mold resistance after being inoculated with a mixture of a conidial suspension of Fusarium thapsinum , Fusarium semitectum , and Curvularia lunata during both periods. Eight of these accessions (PI 586182, PI 586186, PI 647705, PI 647706, PI 647707, PI 647708, PI 647710, and PI 647712) originated from BFA, while one (PI 61666) is from ZAF. The PI 586186 was the only accession that exhibited resistance to both anthracnose and grain mold. The grain mold resistant accession PI 61666 has a panicle shape that resembles a standard United States commercial type sorghum and is also photoperiod insensitive. The results presented herein indicate that the BFA germplasm could be an important source for anthracnose and grain mold resistance genes. The integration of these anthracnose and grain mold resistant germplasm into sorghum breeding programs should aid in expanding the genetic diversity and in the development of new resistant varieties. [ABSTRACT FROM AUTHOR]

A lack of understanding of host-by-pathogen relations can hinder the success of breeding for resistance to a major disease. Fungal strain pathogenicity has to be understood from the virulence it can cause on susceptible genotypes and host resistance indicates which genotypes have resistance genes. Where the two worlds meet lies the place where researchers match the prevalent pathogen in the area of production with resistant varieties. This paper uses ergosterol concentration analysis as a measure of fungal biomass accumulation to assess levels of resistance in host genotypes. 11 sorghum genotypes were inoculated with 5 strains of fungi that are known to be associated with grain mold disease of sorghum. The resulting interaction was analyzed using GGE Biplot analysis and Cluster analysis which showed that none of the genotypes were resistant to Phoma sorghina and Curvularia lunata. Three genotypes were resistant to Fusarium thapsinum. One fungal strain ( Alternaria alternata) does not contribute any significant damage in the grain mold disease. Fusarium graminearum causes very little grain mold disease. There was no correlation between the fungal strains. Visual scoring did not correlate with ergosterol accumulation. Resistance to grain mold in sorghum is shown to be due to vertical or specific resistance genes. Sorghum breeders should, therefore, identify predominant fungal strains in their localities and then locate and tag these resistance genes in their germplasm and pyramid them in commercial varieties. [ABSTRACT FROM AUTHOR]

Grain mold and rust are diseases that can significantly reduce sorghum grain yield. Breeding for resistance to these diseases is hindered by inefficient disease screening. A viable option to greatly improve breeding efficiency is to identify molecular markers or genes linked to the host resistance. In this study, we applied 14,739 single nucleotide polymorphism markers to the sorghum mini core of 242 accessions that had been evaluated for rust resistance in both greenhouse and field and for grain mold in the field for 2 years. Through association mapping we have identified two loci linked to grain mold resistance and five loci linked to rust resistance. Among the two loci linked to grain mold resistance, one contained a homolog of the maize nonhost resistance gene Rxo1. Two of rust-linked loci each contained the rust resistance gene homologous to the maize rust resistance gene Rp1- D which is the B locus (the A locus containing Pu was not linked in this study) and to the wheat rust resistance gene Lr1. The remaining loci contained genes important in other steps of the defense response, such as cyclophilins that mediate resistance response preceding hypersensitive response (HR) and Hin1 directly involved in producing HR. The results from this study will facilitate marker-assisted selection of host resistance to grain mold and rust in sorghum. [ABSTRACT FROM AUTHOR]

Abstract: Grain mold is a serious disease of sorghum causing both qualitative and quantitative losses in grain production. There has been a drastic reduction in area and production in India due to the lack of resistant varieties to manage the disease. Genetic improvement for mold resistance has been suggested as a sole criterion for reducing losses associated with grain mold and several morphological and biochemical traits have been employed to aid screening for resistance. However, there is always a bias with visual scoring systems to rate disease severity; thus, ergosterol and flavan-4-ols content within the grain was evaluated as selection criteria. Twenty-five hybrids were selected based on their visual rating for grain mold resistance and grain color from replicated trials at two locations in India during 2004 and 2005 rainy seasons and grouped into colored resistant, white resistant, colored susceptible and white susceptible. The field grade score (FGS) and threshed grade score (TGS) were strongly and positively correlated with ergosterol content and weakly and negatively correlated with flavan-4-ols. Though the resistant hybrids had higher concentration of flavan-4-ols in methanol and acidified methanol extract compared to the susceptible hybrids, the white grained hybrids had negligible amounts indicating flavan-4-ols concentration is not a suitable selection criterion especially in white grained hybrids. The ergosterol content was higher in susceptible hybrids (19.49μg/g) compared to resistant hybrids (9.96μg/g) and it was marginally less in red hybrids (14.0μg/g) compared to white (17.2μg/g) hybrids. The highly significant correlation of ergosterol content with germination percentage, FGS and TGS validates the use of this trait for identification of grain mold resistant genotypes provided there is no delay in the estimation. Also the significant heterosis obtained for this trait indicates the existence of dominance gene action and suggests that further exploitation of this trait would benefit the development of grain mold resistant hybrids. [Copyright &y& Elsevier]

Abstract: Breeding for resistance to grain mold, an economically important disease of sorghum, has been only partially successful. Hybrid technology is well developed in sorghum due to availability of the cytoplasm male sterility (CMS) system and at present almost all commercial hybrids are based on the A1 CMS system. To compare the available alternate CMS systems for grain mold resistance, 72 hybrids were produced by crossing 36 A-lines (six CMS systems; A1, A2, A3, A4(M), A4(G), A4(VZM) each in six nuclear backgrounds) with two common restorers, and were evaluated during the 2006 and 2007 rainy seasons in grain mold nursery at ICRISAT. Data analyses indicated influence of cytoplasm on the responses of hybrids to grain mold infection as measured by panicle grain mold resistance (PGMR) score. The A1 cytoplasm seemed to contribute to grain mold resistance followed by A4(VZM) and A2 cytoplasms. The A4(M) cytoplasm had superior general combining ability (GCA) effects while the A1 and A4(VZM) cytoplasm based hybrids had superior specific combining ability (SCA) effects on the PGMR score. Almost all hybrids had significant mid-parent heterosis. The A1 cytoplasm is the best suited for the development of sorghum hybrids for the rainy season adaptation with grain mold resistance. However, use of alternate cytoplasms (A2 and A4(VZM)) for hybrid development will not increase susceptibility to grain mold in commercial grain production. [Copyright &y& Elsevier]

Grain mold, induced by a number of non-specific fungi, causes substantial loss to seed/grain yield and quality in sorghum (Sorghum bicolor (L.) Moench). Fungal sporulation and grain mold severity are greatly influenced by temperature and relative humidity (RH) levels. We studied the effects of three incubation temperatures (25, 27 and 28°C) and two sets of RH levels (first set: 85, 90, 95, 98, and 100%, second set: 95, 96, 97, 98, 99 and 100%) on sporulation and grain mold severity in three major mold fungi (Curvularia lunata, Fusarium moniliforme, and Bipolaris australiensis) and on four each of resistant, moderately resistant and susceptible sorghum genotypes for sporulation and mold severity of major fungi. Results indicated that both fungal sporulation and grain mold severity increased on most sorghum genotypes with increasing incubation temperature from 25 – 28°C and RH levels from 95 – 98%. A linear relationship was observed among RH levels, grain mold severity and fungal sporulation. The highest sporulation of all the three fungi occurred at 28°C and 98% RH after 5 days of incubation. Among the three fungi, C. lunata grew and sporulated faster than B. australiensis and F. moniliforme, in that order. Among the sorghum genotypes, IS 25017 supported the least sporulation and had the lowest mold severity, followed by IS 8545 and PVK 801. Seed quality parameters, such as seed germination, seedling vigor index, field emergence potential, dehydrogenase and ά-amylase activities declined significantly with increasing temperature and RH levels that supported heavy sporulation and grain colonization. [ABSTRACT FROM AUTHOR]

White sorghum (Sorghum bicolor) grain from tan plants is more desirable for human or animal consumption. Colonization by Fusarium and Alternaria spp. was assessed for near-isogenic lines differing in wound response (purple or tan) and pericarp color (red or white) in field-grown grain and in greenhouse-grown plants. Seeds were screened on a semi-selective medium for Alternaria and Fusarium. Significantly fewer fungal colonies were obtained from tan plants with white seed, and fewer numbers of Alternaria colonies were obtained from white seed, regardless of plant color, from an irrigated field, while there were no differences in fungal composition of seeds grown at a nonirrigated field. Screening of seed from the nonirrigated field on Fusarium semi-selective medium yielded fewer Fusarium isolations from seed grown on purple plants compared with seed from tan plants. When inoculated with Alternaria sp. and F. moniliforme, there can be no differences in lesion lengths on tan/white plants when compared with purple/red plants in most assays; in one assay, tan/white plants had smaller lesion lengths following inoculation with F. moniliforme. These results suggest that plants with white seeds were as resistant as plants with the red pericarp trait to colonization by Alternaria and Fusarium spp. However, the results also suggest that under appropriate environmental conditions seed from tan plants may be more susceptible to Fusarium spp. than seed from purple plants. [ABSTRACT FROM AUTHOR]

Two genes conferring the brown midrib (bmr) trait had been backcrossed into six elite sorghum lines, resulting in reduced lignin in the bmr lines when compared with the wild-type parent. Seed and leaf tissue from field-grown plants, planted at two locations, were screened for Alternaria spp. and Fusarium spp. on semi-selective media. The results suggest that bmr lines do not have increased susceptibility to colonization by Alternaria spp. However, significantly fewer colonies of Fusarium spp., including Fusarium moniliforme, were recovered from seed of reduced lignin lines from two genetic backgrounds. That the bmr trait in some genetic backgrounds might enable increased resistance to colonization by F. moniliforme was further supported by greenhouse experiments in which peduncles of developing heads were inoculated with F. moniliforme. Mean lesion measurements on bmr lines were significantly lower than those resulting from inoculations on wild-type lines. Analysis of near-isogenic lines revealed that mean lesion lengths on bmr lines were significantly less than those produced on their wild-type counterparts in four of the six genetic backgrounds. These results suggest that reduced lignin lines exhibit, in some cases, increased resistance to Fusarium spp., including F. moniliforme. [ABSTRACT FROM AUTHOR]

Grain mold, caused by several species of fungi, reduces grain yield and quality. This study examined the effect of the two most common grain mold fungi, Fusarium thapsinum and Curvularia lunata, inoculated singly and together on germination and seed mycoflora. Germination rates for the different cultivars have been reported in details previously. C. lunata was the most frequently isolated fungal species followed by F. thapsinum and F. semitectum. Non-inoculated control samples had Alternaria spp. and F. semitectum as themost frequently recovered fungal species followed by C. lunata. There were highly significant negative correlations between germination and C. lunata (r =-0.44 and P < 0.01) in 2000 and between germination and F. thapsinum (r = -0.52 and P < 0.01) in 2001. Significant negative correlations between F. semitectum and F. thapsinum, and highly significant negative correlations between F. thapsinum and C. lunata were observed. Data from this study indicate that the fungal species present, the environment, and the sorghum cultivar all influence seed mycoflora. [ABSTRACT FROM PUBLISHER]

Grain mold of Sorghum bicolor is one of the leading constraints for the production of optimum quality sorghum grain worldwide. Differences in mold levels among different varieties grown in the same environment imply that genes play a role in controlling mold severity. In order to determine if genes that function in active defense responses also affect molding, panicles of resistant and susceptible cultivars were inoculated at anthesis with conidial suspensions of Fusarium thapsinum and Curvularia lunata, the fungi most often found in naturally infected grain. RNA was extracted from the immature floral tissues at various times following inoculation. Levels of mRNA for four known defense-response genes, phenylalanine ammonia lyase (PAL1-1), chalcone synthase (CHS2G), β-1,3-glucanase (GLUC2-1) and chitinase (CHIT25-1) were examined by hybridization to PCR generated clones of the respective genes. Expression of each gene increased rapidly following inoculation with either fungus. Although differences were seen in response to the two pathogens, the general pattern was similar in resistant and susceptible cultivars. The results imply that factors other than the level or timing of active defense responses account for the cultivar differences seen when the plants are challenged at the time of flowering. [Copyright &y& Elsevier]

Field studies were conducted in 2000 and 2001 to investigate effects of two common grain mold fungi, Fusarium thapsinum, Curvularia lunata and a mixture of the two pathogens, on grain mold severity and seed germination in eight sorghum cultivars with different levels of vulnerability to grain mold. Significant effects due to cultivar, fungal treatment and their interaction were observed for grain mold severity (GMS) and for germination. Fungal treatments increased GMS and reduced seed germination in all cultivars. Sureno was the most resistant cultivar evaluated. All other cultivars exhibited susceptible reactions. The type of grain mold fungi present in the field influenced the level of GMS, since cultivars responded differently to inoculation with individual or multiple fungal species. Germination was significantly reduced by all fungal treatments. C. lunata had the most negative effect on germination in 2000 while F. thapsinum produced the most reduction in germination in 2001. These pathogens caused significant reductions in the germination rate, even though GMS ratings on inoculated panicles were low. [Copyright &y& Elsevier]

The effects of various concentrations of chitinase, thaumatin, and their mixtures on radial mycelial growth of five grain molding fungi were studied. When compared with the control, chitinase and chitinase+thaumatin mixtures markedly reduced mycelial growth of the fungal species studied, except for Fusarium semitectum. Reductions in fungal radial mycelial growth of 65.4% for Bipolaris sp. and 61.7% for Colletotrichum graminicola were noted when these fungi were grown on half-strength-potato dextrose agar amended with chitinase. A mixture of chitinase at 50 ml L-1+thaumatin at 37.5 mg L-1 reduced mycelial growth of Bipolaris sp. by 61.7%, C. graminicola by 56.2%, and Curvularia lunata by 44.9% when compared with the control. The levels of thaumatin used in this study were less effective in inhibiting mycelial growth, except for F. semitectum. This study for the first time showed the suppression of mycelial growth in vitro of F. thapsinum, Bipolaris sp., and C. graminicola isolated from sorghum grain. [ABSTRACT FROM AUTHOR]

Grain mold is a globally important panicle disease of sorghum [ Sorghum bicolor (L.) Moench] that occurs between floral anthesis and physiological maturity of the caryopsis. Many fungi, including Fusarium thapsinum, cause grain mold. In this study, sorghum florets of grain mold resistant (Sureno and Tx2911), moderately resistant (SC170), and susceptible (Tx430) cultivars were spray-inoculated with a high density (1 × 106 microconidia/ml) of F. thapsinum at anthesis. Mean caryopsis formation frequencies [CFF = (total caryopses/total spikelets per panicle) × 100] for F. thapsinum-inoculated Sureno and Tx2911 panicles did not significantly differ from their respective controls, however F. thapsinum-inoculated SC170 and Tx430 panicles were significantly less than controls. In addition, CFF was significantly reduced in F. thapsinum-inoculated Tx430 panicles when compared to the F. thapsinum-inoculated grain mold resistant genotypes (P = 0.011). This study suggests that screening of sorghum varieties for caryopsis formation using high-density inoculations at anthesis would provide an additional assay to measure F. thapsinum resistance in the greenhouse. [ABSTRACT FROM AUTHOR]