The Grain Mold Pathogen, Fusarium thapsinum, Reduces Caryopsis Formation in Sorghum bicolor

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.     

Antifungal Proteins during Sorghum Grain Development and Grain Mould Resistance

Proteins potentially inhibitory to the growth of grain‐moulding fungi in vitro have been identified from sorghum seeds. However, their role in vivo during fungi infection is still not clear. The objective of the present study was to evaluate the presence of antifungal proteins (AFPs) during grain development. Sureño (a grain mould‐resistant line), RTx430 (a grain mould‐susceptible) and their F₁ hybrid, were planted at two moisture levels. Caryopses were collected from each genotype every 7 days after anthesis (DAA) during development and maturity of the grain. Significant levels of grain mould occurred naturally. Levels of four AFPs (sormatin, chitinases, β‐1,3‐glucanases and ribosomal‐inactivating proteins) were determined using the immunoblotting technique. During grain development (7–35 DAA), Sureño and the F₁ hybrid showed higher levels of sormatin and chitinase than RTx430. RIPs levels in Sureño and the F₁ hybrid were higher than those in RTx430 after 21 DAA. Sormatin, chitinases, β‐1,3‐glucanases and RIPs levels in Sureño and in the F₁ hybrid were higher than those of RTx430 after grain physiological maturity. AFPs are associated with grain mould resistance because Sureño and the F1 hybrid induce and/or retain higher AFPs levels under grain mould infection pressure than did RTx430.     

Induction of Defence Responses in Roots and Mesocotyls of Sorghum Seedlings by Inoculation with Fusarium thapsinum and F. proliferatum, Wounding and Light

The defence reactions of sorghum seedlings 7 days after inoculation with Fusarium thapsinum and F. proliferatum, and interactions with wounding and exposure to light were studied to determine whether responses to these fungi differed from those to abiotic stresses. In non‐wounded plants, inoculation with both fungi increased concentrations of anthocyanins and soluble phenolics and activities of peroxidase (POX), chitinase and β‐1,3‐glucanase in the roots, and increased β‐1,3‐glucanase activity in the mesocotyls. There was no effect of inoculation on phenylalanine ammonia‐lyase (PAL) activity. Wounding by itself increased anthocyanin content of mesocotyls. Wounding also had a variety of interactions with inoculation. Exposure to light had very little effect on any defence response measured. A time course experiment showed that induction of chitinase and β‐1,3‐glucanase occurred in less than 24 h after inoculation. POX activity increased 2 days after inoculation, followed by a transient increase in PAL activity. The content of anthocyanins and soluble phenolics in roots of inoculated seedlings increased gradually compared with controls over 6 days. The responses of sorghum seedlings to inoculation with F. thapsinum and F. proliferatum were similar to those found by other workers following challenge by necrotrophic pathogens and were different from those induced by wounding and exposure to light.     

Biochemical characterisation of grain mould resistant and susceptible genotypes and PGPR-induced resistance in the host to Curvularia lunata and Fusarium proliferatum

Resistance to biotic stresses in plants is either due to the presence of preformed biochemical compounds or induced in response to external stimulus. In this study, 13 grain mould resistant and seven susceptible lines of sorghum were analysed for biochemical defence mechanism. The levels of total phenols and phenylalanine ammonia lyase were almost same in the resistant and susceptible genotypes. However, two additional isoforms of peroxidase were found in the three of the 13 resistant genotypes. The isoform peroxidase corresponding to the R _f value of 0.25 was found in the resistant genotypes IS 13969, ICSB 377 and IS 8219-1, and two genotypes IS 13969 and ICSB 377 had an additional isoform corresponding to the R _f value of 0.32. The results indicated the genotype specific association of peroxidases with grain mould resistance in sorghum. Nine bacterial strains (Bacillus pumilus SB 21, Bacillus megaterium HiB 9, Bacillus subtilis BCB 19, Pseudomonas plecoglossicida SRI 156, Brevibacterium antiquum SRI 158, B. pumilus INR 7, P. fluorescens UOM SAR 80, P. fluorescens UOM SAR 14, B. pumilus SE 34) were tested to induce systemic resistance in sorghum cultivars 296B and Bulk Y against the highly pathogenic grain mould pathogens Curvularia lunata and Fusarium proliferatum, respectively. The bacterial isolates were effective in inducing resistance in sorghum. Among the strains tested, SRI 158 was found highly effective in reducing grain mould severity in both the genotypes.     

Response of near‐isogenic sorghum lines,differing at the P locus for plant colour,to grain mould and head smut fungi

Leaves and stalks of many sorghum genotypes accumulate dark red or purple pigments upon wounding while some plants, called ‘tan,’ do not. Grains with unpigmented ‘white’ pericarps grown on tan plants are more desirable for food. The hypothesis tested was that pigments in plants protected grain against the panicle diseases grain mould and head smut. Near‐isogenic tan or purple plant colour genotypes with white grain were planted at Lincoln and Ithaca, NE and Corpus Christi, TX. The field grown grain was plated onto semi‐selective media to detect the presence of grain colonisation by mould genera Alternaria, Fusarium and Curvularia. More Fusarium and Curvularia spp. were recovered from grain grown at Corpus Christi than the Nebraska locations; however, there was no indication that the grain from purple plants was more resistant to the three fungal genera. Most fungi were identified morphologically as Alternaria alternata. Molecular identification of Fusarium species, using translation elongation factor 1‐α gene sequences, showed that Fusarium thapsinum and Fusarium proliferatum infected grain at all three locations. Head smut disease of panicles, caused by the fungus Sporisorium reilianum, was assessed at Corpus Christi; surprisingly, purple plants had significantly greater disease incidence than tan plants. We propose that the tan plant colour lines with white grain are promising for development of food‐grade sorghums not more susceptible than pigmented lines to grain mould and head smut.     

Identification and Characterization of Toxigenic Fusaria Associated with Sorghum Grain Mold Complex in India

Fusarium species are dominant within the sorghum grain mold complex. Some species of Fusarium involved in grain mold complex produce mycotoxins, such as fumonisins. An attempt was made to identify Fusarium spp. associated with grain mold complex in major sorghum-growing areas in India through AFLP-based grouping of the isolates and to further confirm the species by sequencing part of α-Elongation factor gene and comparing the sequences with that available in the NCBI database. The dendrogram generated from the AFLP data clustered the isolates into 5 groups. Five species of Fusarium—F. proliferatum, F. thapsinum, F. equiseti, F. andiyazi and F. sacchari were identified based on sequence similarity of α-Elongation factor gene of the test isolates with those in the NCBI database. Fusarium thapsinum was identified as predominant species in Fusarium—grain mold complex in India and F. proliferatum as highly toxigenic for fumonisins production. Analysis of molecular variance (AMOVA) revealed 54% of the variation in the AFLP patterns of 63 isolates was due to the differences between Fusarium species, and 46% was due to differences between the strains within a species.     

Ergosterol concentration and variability in genotype-by-pathogen interaction for grain mold resistance in sorghum

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.     

The effect of inoculating flowers and developing fruits with Botrytis cinerea on post-harvest grey mould of red raspberry

Raspberry flowers were inoculated in the glasshouse and field with dry conidia of Botrytis cinerea and the fruits derived from them subjected to post-harvest rot tests at c. 20°C and high humidity. Apparently healthy fully-ripe picked fruits derived from inoculated flowers developed grey mould faster than those from non-inoculated flowers in all tests. In the glasshouse experiments, fruits from inoculated tightly closed flower buds rotted more slowly than those from inoculated open flowers or those at later developmental stages. Fruits from inoculated whole flowers rotted more rapidly than those from emasculated flowers; the addition of pollen to emasculated flowers had little effect on post-harvest grey mould. In the dry summer of 1984 no fruits in the field from inoculated whole flowers rotted before ripening, but in the wet season of 1985 pre-harvest grey mould was common and the surviving healthy fruits rotted in c. 1 day after picking. Only minor differences were detected in host susceptibility to post-harvest grey mould in both glasshouse and field tests, the ranking of genotypes varied depending on whether or not flowers had been inoculated. The susceptibility of pistils of 40 Rubus genotypes to infection was examined 7 and 28 days after inoculation of stigmas with dry conidia. Conidia germinated on the stigmas and produced hyphae which grew through transmitting tissues of the styles to infect carpels symptomlessly in 17 red raspberries, one blackberry, two Rubus spp. and one hybrid. No germination occurred on stigmas of cv. Carnival and New York Selection 817.     

Field inoculation of sorghum and rice withAzospirillum spp. andHerbaspirillum seropedicae

Two field experiments were carried out at the UAPNPBS experimental station, Seropédica, with two sorghum and one rice cultivars. The establishment, and inoculation effects, ofAzospirillum spp. andHerbaspirillum strains marked with antibiotic resistance were investigated. One grain sorghum (BR 300) and one sugar sorghum (Br 505) cultivar were used.Azospirillum lipoferum strain S82 (isolated from surface sterilized roots of sorghum) established in both cultivars and comprised 40 to 80% of theAzospirillum spp. population in roots and stems 60 days after plant emergence (DAE).Azospirillum amazonense strain AmS91 (isolated from surface-sterilized roots of sorghum) reached only 50%. At 90 DAE, S82 almost disappeared (less than 30% of establishment) while the establishment of AmS91 remained constant in roots and stems. No establishment ofH. seropedicae strain H25 (isolated from surface-sterilized roots of sorghum) orA. lipoferum strain S65 (isolated from the root surface of sorghum) could be observed on inoculated roots. Inoculation with S82, AmS91 or S65 but not withH. seropedicae H25, increased plant dry weight of both cultivars and total N in grain of the grain sorghum. In rice,A. lipoferum Al 121 andA. brasilense Sp 245 (isolated from surface sterilized rice and wheat roots respectively) established in the roots but there was no increase inAzospirillum spp. numbers due to inoculation. None of the strains affected plant growth or rice grain yield.Azospirillum amazonense, A82 andH. seropedicae Z95, which did not establish in roots, significantly enhanced seed germination.     

Fusarium Species from the Fusarium fujikuroi Species Complex Involved in Mixed Infections of Maize in Northern Sinaloa,Mexico

Fusarium species belonging to the Fusarium fujikuroi species complex (FFSC) are associated with maize in northern Mexico and cause Fusarium ear and root rot. In order to assess the diversity of FFSC fungal species involved in this destructive disease in Sinaloa, Mexico, a collection of 108 fungal isolates was obtained from maize plants in 2007–2011. DNA sequence analysis of the calmodulin and elongation factor 1α genes identified four species: Fusarium verticillioides, F. nygamai, F. andiyazi and F. thapsinum (comprising 79, 23, 4 and 2 isolates, respectively). Differential distribution of Fusarium species in maize organs was observed, that is F. verticillioides was the most frequently isolated species from maize seeds, while F. nygamai predominated on maize roots. Mixed infections with F. verticillioides/F. thapsinum and F. verticillioides/F. nygamai were detected in maize seeds and roots, respectively. Pathogenicity assay demonstrated the ability of the four species to infect maize seedlings and induce different levels of disease severity, reflecting variation in aggressiveness, plant height and root biomass. Isolates of F. verticillioides and F. nygamai were the most aggressive. These species were able to colonize all root tissues, from the epidermis to the vascular vessels, while infection by F. andiyazi and F. thapsinum was restricted to the epidermis and adjacent cortical cells. This is the first report of F. nygamai, F. andiyazi and F. thapsinum infecting maize in Mexico and co‐infecting with F. verticillioides. Mixed infections should be taken into consideration due to the production and/or accumulation of diverse mycotoxins in maize grain.     

Spore production and mycorrhizal development in various tropical crop hosts infected with Glomus clarum

Plant growth, mycorrhizal development and vesicular arbuscular spore production were examined in five tropical crop host species inoculated with Glomus clarum and grown in a glasshouse. In one of the two experiments, sequential harvests of maize, sorghum and chickpea were made in order to study spore production in relation to plant growth and mycorrhizal development. Spore numbers in each of these hosts increased at a fairly constant rate until maximum plant dry weight, when spore production ceased. Sorghum and maize produced considerably more spores than chickpea, with spore numbers being closely correlated with mycorrhizal root length. In the second experiment, Glomus clarum was cultured on each of maize, millet, sorghum, groundnut and chickpea for three consecutive generations before cross-inoculation of the spores from each host onto all five hosts. Sporulation with respect to host size was generally greatest when the inoculum used to infect a host had been produced on that host. The growth-promoting effects of the fungus were not influenced by the source of the inoculum. More spores were produced on the cereals than the legumes. Differences in spore numbers amongst hosts and plant generations were apparently influenced mainly by infected root length and by the growth period.     

Banks grass mite (Oligonychus pratensis) abundance on sorghum cultivars with different levels of nitrogen use and metabolism efficiency

Banks grass mite (Oligonychus pratensis (Banks)), abundance was recorded for three years on sorghum (Sorghum bicolor (L.) Moench) cultivars with different levels of nitrogen (N) use and metabolism efficiency. The cultivars included 77CS1, SC630-11E, R6956, and SC325-12. Nitrogen fertilizer was applied to plots containing each cultivar at 0,45, and 180 kg Na ha^–1. Significantly more mites were on plants at 180 kg N ha^–1 than at 0 or 45 kg N ha^–1. The lowest mite densities were recorded on SC325-12, the N-use-inefficient and N-metabolism-efficient cultivar. In July,O. pratensis abundance was statistically equivalent on SC325-12 and on R6956, the other N-metabolism-efficient cultivar. In August, mite densities on R6956 were as high as on 77CS1 and SC630-11E, which are N-metabolism-ineficient cultivars. Mite densities were lower on N-use-inefficient and N-metabolism-efficient sorghum cultivars than on their respective efficiency counterparts. Physiological differences in N-use and metabolism-inefficient cultivars may influence the amount of leaf N plus the amount and form of amino acids and other N-based chemicals in sorghum leaves. These plant chemicals have been shown to influence mite abundance on several hosts, and may have been key to influencing the results of these experiments.     

Antifungal Effect and Protective Role of Ursolic Acid and Three Phenolic Derivatives in the Management of Sorghum Grain Mold Under Field Conditions

In this study, investigation was carried out under in vitro as well as field conditions to explore inhibitors of sorghum grain mold. Phytochemicals, viz., methyl trans‐p‐coumarate (AIC‐1), methyl caffeate (AIC‐2), syringic acid (AIC‐3), and ursolic acid (UA), at different concentrations (500, 750, and 1000 ppm) were tested on spore germination of Alternaria alternata, Curvularia lunata, Fusarium moniliforme, F. pallidoroseum, and Helminthosporium sp. Significant growth inhibition (P < 0.001) was observed against all fungi except A. alternata which was found to be resistant to AIC‐3. Further, two separate sets of field experiments involving spraying of water and F. moniliforme suspension over chemicals treated (1000 ppm) sorghum panicles were done. The levels of protection varied with different treatments which were graded using a standard 1 – 9 rating scale. The Fusarium‐challenged panicles (FCP) showed lesser susceptibility and decreased the rate of infection of grain mold (grade 7.0), compared to simple UA, AIC‐2, and AIC‐1 treatments (7.4, 7.6, and 8.0 grade, resp.). The HPLC quantification of differentially induced phenolic acids in treated sorghum grains substantiated this effect disclosing the higher accumulation of chlorogenic, vanillic, and salicylic acids in FCP. This might be due to defensive induction of these acids by the plants. Although mold control by examined chemicals were lesser than the standard Tilt (grade 5.9), they were found to be nontoxic to mammalian cells under cytotoxicity assay.     

Inheritance of osmotic adjustment to water stress in three grain sorghum crosses

Water stress is one of the major constraints to the grain yield of sorghum in tropical and sub-tropical areas of the world. Osmotic adjustment has been widely proposed as a plant attribute that confers adaptation to water stress. The inheritance of osmotic adjustment to water stress was investigated in a series of generations derived from the three possible bi-parental crosses between two inbred sorghum lines with a high capacity for osmotic adjustment (Tx2813 and TAM422; high-OA lines) and one with a low capacity (QL27; low-OA line). Broad-sense heritability on a single-plant basis was generally found to be high. Analysis of segregation ratios by the mixture method of clustering identified two independent major genes for high osmotic adjustment. The line Tx2813 possessed a recessive gene which is given the symbol oa1; the line TAM422 possessed an additive gene which is given the symbol OA2. There was some evidence that there may be other minor genes which influence the expression of osmotic adjustment in these crosses as two putative transgressive segregants, with higher osmotic adjustment than the parents, were identified from the cross between Tx2813 and TAM422. Populations of recombinant inbred lines were developed and characterised for osmotic adjustment for two of the crosses (QL27 x TAM422, low-OA x high-OA; Tx2813 x TAM422, high-oal x high-OA2). These will be used to conduct experiments which test hypotheses about the contribution of the high-osmotic-adjustment genes to the grain yield of sorghum under a range of water-stress conditions.     

Assessment of sorghum genetic resources of Ethiopia for anthracnose (Colletotrichum sublineolum Henn.) resistance and agronomic traits

Sorghum anthracnose caused by Colletotrichum sublineolum Henn. is one of the key diseases limiting sorghum production and productivity. Development of anthracnose‐resistant sorghum genotypes possessing yield‐promoting agronomic traits is an important breeding goal in sorghum improvement programs. The objective of this study was to determine the responses of diverse sorghum genetic resources for anthracnose resistance and agronomic traits to identify desirable lines for breeding. A total of 366 sorghum collections and three standard checks were field evaluated during the 2016 and 2017 cropping seasons. Lines were artificially inoculated with a virulent pure isolate of the pathogen. Anthracnose disease severity was assessed to calculate the area under disease progress curve (AUDPC). Agronomic traits such as panicle length (PL), panicle width (PW), head weight (HW) and thousand grain weight (TGW) were measured. Lines showed highly significant differences (p < .001) for anthracnose severity, AUDPC and agronomic traits. Among the collections 32 lines developed levels of disease severity between 15% and 30% in both seasons. The following sorghum landraces were selected: 71708, 210903, 74222, 73955, 74685, 74670, 74656, 74183, 234112, 69412, 226057, 214852, 71420, 71484, 200126, 71557, 75120, 71547, 220014, 228179, 16212, 16173, 16133, 69088, 238388, 16168 and 71570. These landraces had a relatively low anthracnose severity possessing farmer‐preferred agronomic traits. The selected genotypes are useful genetic resources to develop anthracnose‐resistant sorghum cultivars.     

Natural occurrence of trichothecene-producing Fusaria isolated from India with particular reference to sorghum

In this study a total of 167 isolates collected from different food materials (68.8% from sorghum and the remaining from various other food materials) were assayed by PCR for amplification of the tri 5 gene present in trichothecene-producing Fusaria. Amplification of the tri 5 fragment was observed in 45 isolates (39 isolates from sorghum and 6 isolates from vegetables). Isolates found positive for presence of the tri 5 gene were classified into different morphological groups based on their cultural and conidial characters; 11 of the tri 5 positive isolates from moldy grains of sorghum, one from each morphology group were selected for further analyses. Five deoxynivalenol producers and three deoxynivalenol and Fusarenon-X producers were detected by analysing culture filtrates of the 11 isolates using GC-MS. One isolate each were identified as producers of NIV alone, or NIV along with DON or DAS toxins. Identification of these isolates to the species level was carried out using spore morphology and sequence comparison of the translation elongation factor 1-alpha (EF-1α) gene against the database as well as using phylogenetic analyses. The isolates were identified as Fusarium proliferatum (6), F. nelsonii (2), F. equiseti (1), F. thapsinum (1) and F. sacchari (1). Amplified Fragment Length Polymorphism (AFLP) based grouping clustered the isolates of same species together. This is the first detailed study of trichothecene production by Fusarium spp. associated with sorghum grain mold in India and the identification of F. nelsonii and F. thapsinum as producers of trichothecenes.     

The Physiology of Heterosis in Sorghum with Respect to Environmental Stress

The hypothesis that heterosis in biomass production of sorghum(Sorghum bicolor L. Moench) may be ascribed to stability incarbon exchange rate (CER) over a wide range of environmentalconditions was evaluated. This hypothesis was based on previousresults from detached leaves that hybrids sustained greaterCER over a wider temperture range than their parents. Two grain sorghum hybrids (ATx378/RTx430 and ATx378/RTx434)and their parental lines were grown in the greenhouse in a gradientof ambient temperatures under two water regimes (well-irrigatedand drought up to heading). Plant water-use (estimated by weighingpots), leaf area, leaf gas exchange, grain yield, and above-groundbiomass were determined. Significant heterosis was found for biomass, grain yield perplant, and grain number per panicle. No heterosis occurred forharvest index, indicating that heterosis in grain yield wasdue to heterosis in biomass. Neither growth duration nor leafarea could explain heterosis in biomass. CER and stomatal conductancefor hybrid ATx378/RTx430 in the controls were greater than forboth its parents at leaf temperatures above 38 °C. This,however, was not observed in the other hybrid which was lessheterotic for biomass and grain yield in the controls. WhenCER data were subjected to a stability analysis by joint linearregression, the two hybrids had greater CER than their respectiveparents especially under conditions favouring high CER. Whenextreme stress conditions developed, the hybrid's performancedepended on its genetic background more than on heterosis. Sorghum, Sorghum bicolor L. Moench., heterosis, hybrids, photosynthesis, transpiration, stomata, drought, heat, temperature     

Host plant resistance to grain mould in germplasm accessions of pearl millet (Pennisetum glaucum [L.] R. Br.)

Abstract

The paucity of information on the moulds in Indian pearl millet (Pennisetum glaucum) led to the studies that were conducted at ICRISAT, India to evaluate (a) 447 germplasm accessions of 32 countries for mould reaction in rainy season, (b) threshed grain mould rating (TGMS) and mycoflora on grains of each accession, and (c) mould scores in field and in vitro. Post physiological maturity evaluation showed that 16% of the accessions secured a mould rating of 2. In TGMS, 18% were mould free and 57% secured a rating of 2 on a 1 – 9 scale. Assessment of twenty representative accessions in vitro against individual and mixed conidial suspensions (1 × 10⁽⁶⁾ conidia ml^(?1)) of Fusarium moniliforme, F. pallidoroseum and Curvularia pennisetti indicated significant correlation (r = 0.97) between the overall field and in vitro scores of mixed spores inoculations. The mycoflora for TGMS in blotter test revealed that Fusarium moniliforme, F. pallidoroseum, Curvularia pennisetti, Helminthosporium spp., Alternaria spp. and Colletotrichum spp. to be the major fungi affecting pearl millet grain. It is advisable to harvest panicles at the physiological maturity stage to obtain better quality grains. A strong negative correlation between TGMS and % GS (r = 0.4601) and positive correlation between TGMS and % UGS (r = 0.4654) indicated that, the lesser the threshed grain mould rating higher the % seed germination.     

Developing a flexible,high‐efficiency Agrobacterium‐mediated sorghum transformation system with broad application

Sorghum is the fifth most widely planted cereal crop in the world and is commonly cultivated in arid and semi‐arid regions such as Africa. Despite its importance as a food source, sorghum genetic improvement through transgenic approaches has been limited because of an inefficient transformation system. Here, we report a ternary vector (also known as cohabitating vector) system using a recently described pVIR accessory plasmid that facilitates efficient Agrobacterium‐mediated transformation of sorghum. We report regeneration frequencies ranging from 6% to 29% in Tx430 using different selectable markers and single copy, backbone free ‘quality events’ ranging from 45% to 66% of the total events produced. Furthermore, we successfully applied this ternary system to develop transformation protocols for popular but recalcitrant African varieties including Macia, Malisor 84‐7 and Tegemeo. In addition, we report the use of this technology to develop the first stable CRISPR/Cas9‐mediated gene knockouts in Tx430.