Sorghum Tissues Research Articles

Cadmium Phytoremediation Effect of Sweet Sorghum Assisted with Citric Acid on Typical Parent Soil in Southern China

Sweet sorghum has a large biomass and strong cadmium (Cd) absorption capacity, which has the potential for phytoremediation of Cd-contaminated soil. In order to study the Cd phytoremediation effect of sweet sorghum assisted with citric acid on the typical parent materials in southern China, a field experiment was carried out in two typical parent material farmland areas (neutral purple mud field and jute sand mud field) with Cd pollution in Hunan Province. The results showed that:① Citric acid had no inhibitory effect on the growth of sweet sorghum. After the application of citric acid, the aboveground biomass of sweet sorghum at the maturity stage increased by 10.1%-24.7%. ② Both sweet sorghum planting and citric acid application reduced the soil pH value, and the application of citric acid further reduced the soil pH value at each growth stage of sweet sorghum; this decrease was greater in the neutral purple mud field, which decreased by 0.24-0.72 units. ③ Both sweet sorghum planting and citric acid application reduced the total amount of soil Cd, and the decreases in the neutral purple mud field and jute sand mud field were 23.8%-52.2% and 17.1%-31.8%, respectively. The acid-extractable percentage of soil Cd in both places increased by 38.6%-147.7% and 4.8%-22.7%, respectively. ④ The application of citric acid could significantly increase the Cd content in various tissues of sweet sorghum. The Cd content in the aboveground part of the plant in the neutral purple mud field was higher than that in the jute sand mud field, and the Cd content in stems and leaves was 0.25-1.90 mg·kg-1 and 0.21-0.64 mg·kg-1, respectively. ⑤ After applying citric acid, the Cd extraction amount of sweet sorghum in neutral purple mud soil in the mature stage reached 47.56 g·hm-2. In summary, citric acid could enhance the efficiency of sweet sorghum in the phytoremediation of Cd-contaminated soil, and the effect was better in neutral purple mud fields. This technology has the potential for remediation coupled with agro-production for heavy metal-contaminated farmland.

The influence of microstructural characteristics and cell wall material properties on the mechanical behaviors of different tissues of sorghum stems

Sorghum stems comprise different tissue components, i.e., rind, pith, and vascular bundles in the rind and pith regions, of different cell morphologies and cell wall characteristics. The overall responses of stems to mechanical loadings depend on the responses of these tissues themselves. Investigating how each tissue deforms to various loading conditions will inform us of the failure mechanisms in sorghum stems when exposed to wind loadings, which can guide the development of lodging-resistant variants. To this end, numerical analyses were implemented to investigate the effects of cell morphologies and cell wall properties on the overall mechanical responses of the above four tissues under tension and compression. Microstructures of different tissues were constructed from microscopic images of the tissues using computer-aided design (CAD), which were then used for finite element (FE) analyses. Shell finite elements were used to model the cell walls, and the classical lamination model was used to determine the overall mechanical responses of cell walls having different fiber composite arrangements. The results from the numerical analyses helped explain how the loading (boundary) conditions, the cell microstructures, the mechanical properties of cell walls of different tissues, the cell wall thickness, the microfibril angle (MFA) of fiber composites of the cell walls, and the turgor pressure affected the overall mechanical responses of the tissues. Tissue stiffening or softening behaviors were attributed to different microstructural deformations, i.e., local or global buckling of cell walls, cell collapse, densifications of cells, or reorientation and rearrangement of cells. The mechanical properties and thickness of cell walls only affected the stiffness and load-bearing ability of the tissues. The turgor pressure affected the compressive responses but its effect on tensile responses was negligible. The MFA had a significant influence on the stiffness and load-bearing ability when the tissues were loaded along their longitudinal axis, but it had an insignificant effect on loading in the transverse direction. Tissues with smaller cell sizes and denser cells were stronger and stiffer than those with larger cell sizes. The numerical simulations also revealed that rind and rind vascular bundles were stiffer and had higher load-bearing ability than pith and pith vascular bundles.

RNA-Seq Analysis of Aboveground and Underground Parts of Biomass Sorghum Was Performed to Evaluate Its Suitability for Environmental Remediation.

"Alto2" is a new biomass sorghum variety, which has the characteristics of fast growth, high growth, and strong cadmium (Cd) resistance, so it has the application prospect of soil remediation plants. In order to reveal the Cd resistance mechanism of this plant and pave the way for genetic breeding and cultivation of efficient remediation plants in the future, in this research, through the determination of Cd content in various tissues of sorghum under Cd stress and the physicochemical response combined with RNA-Seq analysis, the mechanism of Cd resistance of "Alto2" was initially revealed. The results show biomass sorghum "Alto2" was mainly connected with aboveground and underground parts through the MAPK signaling pathway and plant hormone signaling pathway, and transmit stress signal in response to Cd stress. Chelase and metal-binding proteins may be the functional genes mainly responsible for Cd enrichment and transport and regulated by stress signals. However, the expression of aboveground transporters was not significant. This may be because Cd in biomass sorghum is mainly concentrated in the underground part and is enriched by the chelation of secondary metabolites from plant roots by the cell wall leading to inhibition of aboveground transporter expression. The results of this study indicate that the biomass sorghum "Alto2" on Cd has high resistance, but the lack of the aboveground enrichment of transportability requires further research to improve the Cd transportability of this plant.

Characterization of the m6A gene family in sorghum and its function in growth, development and stress resistance

N6-methyladenosine (m6A) is one of the most common types of RNA modification and is involved in regulating various stages of plant growth and development. Sorghum is a C4 crop with the characteristics of fast growth, high yield, and resistance to salinity and alkalinity. However, the systematic identification of m6A regulatory components in sorghum and the exploration of their potential functions in stress responses have not yet been achieved. In this study, 29 m6A-regulated genes were identified from the genome of sorghum, and gene signatures were analyzed. The potential functions of m6A regulatory components involved in sorghum growth, development, and crop yield were predicted by integrating the expression profiles in different sorghum tissues in a series of developmental stages under different environmental stresses. Most of the m6A-regulated genes were differentially expressed when the response of sorghum to environmental stress was regulated, and the trends were different in response to different environmental stresses. Transient transformation experiments showed that m6A-regulated genes mediated sorghum responses to stress by regulating reactive oxygen species accumulation. The results of this study suggested that m6A-regulated genes played an important role in regulating sorghum growth and responding to environmental stresses, providing a reference for improving crop quality and stress resistance from an epigenetic perspective.

Response of nutrient elements in leaf tissues of sweet sorghum (Sorghum bicolor) to interactive effects of soil-drenched triterpenoid phytonematicides

Root-knot (Meloidogyne species) nematode population densities on various crops, including sweet sorghum, were consistently decreased by three triterpenoid phytonematicides that are currently available as Nemarioc-AL, Nemafric-BL and Mordica. These compounds have chemically different active ingredients. The interaction between triterpenoid phytonematicides and the accumulation of nutrients in plant leaf tissues has not yet been studied, with the exception of Nemarioc-AL and Nemafric-BL. The objective of this study was to investigate the interactive effects of triterpenoid phytonematicides on accumulation of nutrient elements in leaf tissues of sweet sorghum under microplot conditions in Limpopo Province, South Africa during 2020 and 2021. Nemarioc-AL, Nemafric-BL and Mordica were laid in a 2 × 2 × 2 factorial experiment, respectively. The test treatments were arranged in a randomized complete block design, with eight replications, conducted on artificial microplots containing steam pasteurized soil. At 150 days after inoculation, the second order interaction (Nemarioc-AL × Nemafric-BL × Mordica) significantly (P=0.05) increased accumulation of Ca, K and Mg in leaf tissues of sweet sorghum, but without affecting P, Fe, Na and Zn. Relative to untreated control, second order interaction increased Ca, K and Mg by 206, 164 and 289%, respectively. In accordance with the density-dependent growth principles of entities exposed to allelochemicals, soil-drenched administration of triterpenoid phytonematicides dramatically modified the accumulation of nutritional components in leaf tissues of sweet sorghum.

Zinc supply influenced the growth, yield, zinc content, and expression of ZIP family transporters in sorghum.

Zinc deficiency altered shoot and root growth, plant biomass, yield, and ZIP family transporter gene expression in sorghum. Zinc (Zn) deficiency affects several crop plants' growth and yield, including sorghum. We have evaluated the sorghum under various concentrations of Zn supply for phenotypic changes, Zn content, and expression of Zn-regulated, iron-regulated transporter-like proteins (ZIP) family genes. Zn deficiency reduced the shoot and root growth, plant biomass, and yield by > 50%. The length and number of lateral roots were increased by more than 50% under deficient Zn compared to sufficient Zn. Ten SbZIP family transporter genes showed dynamic expression in shoot and root tissues of sorghum under deficient and sufficient Zn. SbZIP2, 5, 6, 7, and 8 were expressed in all tissues under deficient and sufficient Zn. SbZIP2, 4, 5, 6, 7, 8, and 10 were highly induced in shoot tissues by deficient Zn. The expression level of SbZIP6, 7, 8, and 9 was higher in root tissues under deficient Zn. The phylogenetic analysis revealed that most SbZIP family proteins are closely associated with the ZmZIP family of maize. The functional residues His177 and Gly182 are fully conserved in all SbZIP family transporters, as revealed by homology modeling and multiple sequence alignment. This study may provide a foundation for improving the Zn-use efficiency of sorghum.

Sorghum WRKY transcription factor SbWRKY45 enhanced seed germination under drought stress in transgenic Arabidopsis

The WRKY transcription factors (TFs) family is an important family of plant-specific TFs, playing vital roles in various abiotic and biotic stress responses. WRKY TFs are gaining considerable attention due to their significant roles in stress responses. However, their functions in sorghum (Sorghum bicolor) are lagging behind. In this study, a WRKY gene designated as SbWRKY45 was isolated and characterized from sorghum. SbWRKY45, belonging to Group IIa, consists of one intron and two exons and encodes 430 amino acids. SbWRKY45 is located in chromosome 4. The cis-element prediction analysis showed that the promoter region of SbWRKY45 has several abiotic stress-associated elements. The qRT-PCR results showed that SbWRKY45 was significantly up-regulated in response to drought and cold under salt treatments, was notably changed, and was induced weakly under heat stress. SbWRKY45 exhibited a response to stress in different sorghum tissues, including leaves, stems, and roots. A tissue-specific expression pattern showed that SbWRKY45 was highly expressed in roots compared with leaves and stems, suggesting that SbWRKY45 may play an important role in roots. Overexpression of SbWRKY45 increased germination rates and promoted root growth in transgenic Arabidopsis under drought stress. Taken together, our findings indicate that SbWRKY45 may be involved in mediating the response to drought stress and play a vital role in the abiotic stress response of sorghum

Profiling of transcriptional regulators associated with starch biosynthesis in sorghum (Sorghum bicolor L.)

Starch presents as the major component of grain endosperm of sorghum (Sorghum bicolor L.) and other cereals, serving as the main energy supplier for both plants and animals, as well as important industrial raw materials of human beings, and was intensively concerned world widely. However, few documents focused on the pathway and transcriptional regulations of starch biosynthesis in sorghum. Here we presented the RNA-sequencing profiles of 20 sorghum tissues at different developmental stages to dissect key genes associated with sorghum starch biosynthesis and potential transcriptional regulations. A total of 1,708 highly expressed genes were detected, namely, 416 in grains, 736 in inflorescence, 73 in the stalk, 215 in the root, and 268 genes in the leaf. Besides, 27 genes encoded key enzymes associated with starch biosynthesis in sorghum were identified, namely, six for ADP-glucose pyrophosphorylase (AGPase), 10 for starch synthases (SSs), four for both starch-branching enzymes (SBE) and starch-debranching enzymes (DBEs), two for starch phosphorylases (SPs), and one for Brittle-1 (BT1). In addition, 65 transcription factors (TFs) that are highly expressed in endosperm were detected to co-express with 16 out of 27 genes, and 90 cis-elements were possessed by all 27 identified genes. Four NAC TFs were cloned, and the further assay results showed that three of them could in vitro bind to the CACGCAA motif within the promoters of SbBt1 and SbGBSSI, two key genes associated with starch biosynthesis in sorghum, functioning in similar ways that reported in other cereals. These results confirmed that sorghum starch biosynthesis might share the same or similar transcriptional regulations documented in other cereals, and provided informative references for further regulatory mechanism dissection of TFs involved in starch biosynthesis in sorghum.

HEIGHTENING SORGHUM NITROGEN UPTAKE WHILE MAINTAINING OPTIMAL SOIL NUTRIENT LEVELS THROUGH MINERAL FERTILISER APPLICATION

Improving nutrient management of soils is important in subsistence farming systems in the tropics due to declining soil fertility resulting from continuous cropping coupled with inadequate nutrient replenishment. Balancing nutrient inputs with crop removal is crucial in reducing the build-up of nutrients and minimises nutrient losses through different pathways, thus reducing the cost of production. This study aimed at evaluating the effect of N and P fertiliser on sorghum N uptake at Kampi ya Mawe (KYM) in Makueni County and Katumani (KAT) in Machakos County, Kenya. Two factors (nitrogen and phosphorus) each at two levels (0 and 75 kg ha-1) were evaluated, resulting in four treatments, each replicated thrice. At KYM, N content in sorghum tissues increased by 24.2% in comparison with the control following application of N at 75 kg ha-1. At KAT, plots amended with N and P at 75 kg ha-1 resulted in the highest N content in sorghum tissues at the three sorghum development stages assessed. At the seedling stage, an increase of 18.8% was observed. Sole N application led to an increase in N content in sorghum tissues of 17.6% at the seedling stage. A positive linear relationship between NO3-N and N content in sorghum tissues was also observed. The study showed that soil N uptake was higher in the early growth stages of sorghum. The results of this study are essential to farmers and extension officers as a guide to ensure timely fertiliser application to ensure optimum utilisation of nutrients during crop growth.

Evolution of an intermediate C4 photosynthesis in the non-foliar tissues of the Poaceae.

Carbon concentrating mechanisms (CCMs) in plants are abaptive features that have evolved to sustain plant growth in unfavorable environments, especially at low atmospheric carbon levels and high temperatures. Uptake of CO2 and its storage in the aerenchyma tissues of Lycopsids and diurnal acidity fluctuation in aquatic plants during the Palaeozoic era (ca. 300Ma.) would represent the earliest evolution of a CCM. The CCM parts of the dark reactions of photosynthesis have evolved many times, while the light reactions are conserved across plant lineages. A C4 type CCM, leaf C4 photosynthesis is evolved in the PACMAD clade of the Poaceae family. The evolution of C4 photosynthesis from C3 photosynthesis was an abaptation. Photosynthesis in reproductive tissues of sorghum and maize (PACMAD clade) has been shown to be of a weaker C4 type (high CO2 compensation point, low carbon isotope discrimination, and lack of Rubisco compartmentalization, when compared to the normal C4 types) than that in the leaves (normal C4 type). However, this does not fit well with the character polarity concept from an evolutionary perspective. In a recent model proposed for CCM evolution, the development of a rudimentary CCM prior to the evolution of a more efficient CCM (features contrasting to a weaker C4 type, leading to greater biomass production rate) has been suggested. An intermediate crassulacean acid metabolism (CAM) type of CCM (rudimentary) was reported in the genera, Brassia, Coryanthes, Eriopsis, Peristeria, of the orchids (well-known group of plants that display the CAM pathway). Similarly, we propose here the evolution of a rudimentary CCM (C4-like type pathway) in the non-foliar tissues of the Poaceae, prior to the evolution of the C4 pathway as identified in the leaves of the C4 species of the PACMAD clade.

Unraveling Sorghum Allelopathy in Agriculture: Concepts and Implications.

Allelopathy is an ecological phenomenon that involves the production and release of biomolecules from different crops, cultivated plants, and bacteria or fungi into the soil rhizosphere and impacts other organisms in the vicinity. Sorghum possesses vital allelopathic characteristics due to which it produces and releases different biomolecules from its root hairs, stems, and grains. Several studies have reported that sorghum acts as an allelopathic crop, decreasing the growth and eco-physiological attributes of surrounding plants and weeds growing simultaneously or subsequently in the field. Sorghum allelopathy has been exploited in the context of green manure, crop rotations, cover crops, and intercropping or mulching, whereas plant aqueous extracts or powder might be an alternate method of weed control. A diverse group of allelochemicals, including benzoic acid, p-hydroxybenzoic acid, vanillic acid, ferulic acid, chlorogenic acid, m-coumaric acid, p-coumaric acid, gallic acid, caffeic acid, p-hydroxibenzaldehyde, dhurrin, sorgoleone, m-hydroxybenzoic acid and protocatechuic acid, have been isolated and identified from different plant tissues of sorghum and root exudates. These allelochemicals, especially sorgoleone, have been investigated in terms of their mode(s) of action, specific activity and selectivity, release in the rhizosphere and uptake and translocation in sensitive species. The present review describes the importance of sorghum allelopathy as an ecological tool in managing weeds, highlighting the most recent advances in the allelochemicals present in sorghum, their modes of action, and their fate in the ecosystem. Further research should focus on the evaluation and selection of sorghum cultivars with high allelopathic potential, so that sorghum allelopathy can be better utilized for weed control and yield enhancement.

Effect of tannins on microwave-assisted extractability and color properties of sorghum 3-deoxyanthocyanins

Sorghum derived 3-deoxyanthocyanins (3-DXA) are of growing interest as natural food colors due to their unique stability compared to anthocyanins, but are generally difficult to extract. Microwave-assisted extraction (MAE) can dramatically improve extraction efficiency of 3-DXA from sorghum tissue. However, condensed tannins common in some sorghums could impact MAE extractability and color properties of 3-DXA. The objective of this work was to determine how presence of condensed tannins affect MAE extractability, stability, and color properties of sorghum 3-DXA. Sorghums of varying 3-DXA profile and tannin content, as well as purified tannins, were subjected to MAE and pigment yield and profile, aqueous color properties and stability at pH 1 – 5 monitored over time using, UV–vis spectroscopy, colorimetry, and UPLC-MS. The relative yield of 3-DXA from tannin sorghums was higher (3 – 10-fold) after MAE than from non-tannin sorghum (2-fold). During MAE, condensed tannins underwent extensive oxidative depolymerization to anthocyanidins (cyanidin and 7-O-methylcyanidin), which caused the tannin-sorghum pigment extracts to have a redder hue (12–43H°) compared to the non-tannin pigment extract (58H°). The tannin-derived anthocyanidins transformed over time into xanthylium pigments, resulting in increased extract H°. Tannins enhanced both color intensity (pH 1) and stability (pH 3–5) of the 3-DXA over 14 days, indicating they acted as copigments. The presence of tannins in sorghum enhances MAE extractability of 3-DXA from sorghum tissue, and could also potentially enhance their functionality in aqueous food systems. However, the initial changes in extract hue properties due to tannin-derived anthocyanidins should be considered.

English

The diversity and genetic differentiation of populations of Fusarium species associated with sorghum fields, both endophytes obtained from sorghum performing and non performing plants and isolates obtained from two sampling periods were investigated. Fusarium specific Internal Transcribed Spacer 2 (FITS2) primers set were used to assess genetic variability of 32 isolates from susceptible Fusarium spp. endophytes from Sorghum tissues. Fusarium thapsinum (Gibberella thapsina) with 68.75% of the isolates constituted the majority of Fusarium spp. isolated in performing plants. Gibberella thapsina species identified are described as non-pathogenic and associated to performing plant of sorghum. Previously, some species of Fusarium thapsinum have been recognized as pathogenic and responsible for yield losses in several cereal crops including Sorghum bicolor produced in Burkina Faso. The other Fusarium spp. identified in this study including Fusarium subglutinans, Fusarium chlamydosporum, Gibberella intermedia, Fusarium dlaminii, Fusarium oxysporum, Fusarium proliferatum, and Fusarium spp. An additional unknown fungi species were also identified. A diverse population of 10 sequence types was found, although 8 sequence types represented nearly two-thirds of the isolates studied. The sequence types were placed in different phylogenetic clades within Fusarium spp., and endophytic isolates were not monophyletic. Phylogenetic analysis from Neighbor-Joining/UnWeighted Neighbor-Joining showed a high genetic relationship among these 32 isolates of Fusarium spp. and high variation in FITS sequence of them. The use of specific phylomarker of the genus Fusarium allowed to identify the endophytic species of this genus and to establish the phylogenetic relationships between the endophytic species of Fusarium. The phylogenetic analysis revealed three groups of the fungi. However, no relationship between these groups and the geographical origins of these fungi has been established.   Key words: Fusarium thapsinum, endophyte, FITS2 marker, sorghum.

Variation in production of cyanogenic glucosides during early plant development: A comparison of wild and domesticated sorghum

Domestication has narrowed the genetic diversity found in crop wild relatives, potentially reducing plasticity to cope with a changing climate. The tissues of domesticated sorghum (Sorghum bicolor), especially in younger plants, are cyanogenic and potentially toxic. Species of wild sorghum produce lower levels of the cyanogenic glucoside (CNglc) dhurrin than S. bicolor at maturity, but it is not known if this is also the case during germination and early growth. CNglcs play multiple roles in primary and specialised metabolism in domesticated sorghum and other crop plants. In this study, the temporal and spatial distribution of dhurrin in wild and domesticated sorghum at different growth stages was monitored in leaf, sheath and root tissues up to 35 days post germination using S. bicolor and the wild species S. brachypodum and S. macrospermum as the experimental systems. Growth parameters were also measured and allocation of plant total nitrogen (N%) to both dhurrin and nitrate (NO3−) was calculated. Negligible amounts of dhurrin were produced in the leaves of the two wild species compared to S. bicolor. The morphology of the two wild sorghums also differed from S. bicolor, with the greatest differences observed for the more distantly related S. brachypodum. S. bicolor had the highest leaf N% whilst the wild species had significantly higher root N%. Allocation of nitrogen to dhurrin in aboveground tissue was significantly higher in S. bicolor compared to the wild species but did not differ in the roots across the three species. The differences in plant morphology, dhurrin content and re-mobilisation, and nitrate/nitrogen allocation suggest that domestication has affected the functional roles of dhurrin in sorghum.

Micronutrient Status in Soil and Sorghum (<i>Sorghum bicolor</i> (L.) Moench) Tissues in Daro Labu District, West Hararghe Zone of Oromia Region, Eastern Ethiopia

Updated information on status of soil fertility and the soil plant nutrient relationship is important for soil fertility improvement and subsequently increases crop yields. The study was conducted to assess soil fertility status of sorghum fields and micronutrient concentration in sorghum tissues and examine the relationship between soil and sorghum tissue test micronutrient at Daro Labu district, Eastern Ethiopia. Twelve sorghum growing fields from four kebeles were selected purposively. Field survey was conducted to collect general information about soil fertility management practices and record spatial data. A total of 12 composite soil samples from the depth of 0-20 cm and 12 sorghum tissue samples were collected. The data were analyzed by using SPSS version 20. The soil texture was sandy clay loam and sandy loam. Soil bulk density was ranged from 1.35 to 1.53 g cm^-3 within an acceptable range. The total porosity of soil was ranged from 41.49 to 45.27%. The soils were very low in OM content with values ranging from 0.60 to 1.18%. The TN content of soil was ranged from 0.06 to 0.14% which was low. The soils were better in their available P content. The CEC of soil ranged from medium to high. Exchangeable Ca and Mg were found to be high and medium respectively. Exchangeable K was low to medium which showed deficiency of K. The soil had adequate level of DTPA extractable Fe and Mn whereas deficiency of Cu and B was recorded. The 75% of soil was showed Zn deficiency. Sorghum tissue had adequate concentration of Fe and Mn. However, 66.67%, 16.67% and 58.33% of sorghum tissues were deficient with Cu (0.35 - 10.53 mg kg^-1), Zn (7.06 - 20.39 mg kg^-1) and B (0.18 - 4.69 mg kg^-1) concentration respectively. The extractable Fe, Mn, Cu, Zn and B concentration in a plant tissue were positively correlated with their respective soil micronutrients. The soil of the study areas were at normal condition in terms of the studied soil physical properties. The data regarding chemical fertility parameters indicated that OM, TN, P, K, Cu, Zn and B are the main limiting factors for crop production. Therefore, application of organic materials (compost, vermicompost, FYM, crop residue management) and balanced minerals fertilizers containing K, Cu, Zn and B could be recommended. Moreover, further studies on application rates of those fertilizers by considering soil type and crop variety are suggested.

Structure and Function of the Cytochrome P450 Monooxygenase Cinnamate 4-hydroxylase from Sorghum bicolor.

Cinnamate 4-hydroxylase (C4H; CYP73A) is a cytochrome P450 monooxygenase associated externally with the endoplasmic reticulum of plant cells. The enzyme uses NADPH-cytochrome P450 reductase as a donor of electrons and hydroxylates cinnamic acid to form 4-coumaric acid in phenylpropanoid metabolism. In order to better understand the structure and function of this unique class of plant P450 enzymes, we have characterized the enzyme C4H1 from lignifying tissues of sorghum (Sorghum bicolor), encoded by Sobic.002G126600 Here we report the 1.7 Å resolution crystal structure of CYP73A33. The obtained structural information, along with the results of the steady-state kinetic analysis and the absorption spectroscopy titration, displays a high degree of similarity of the structural and functional features of C4H to those of other P450 proteins. Our data also suggest the presence of a putative allosteric substrate-binding site in a hydrophobic pocket on the enzyme surface. In addition, comparing the newly resolved structure with those of well-investigated cytochromes P450 from mammals and bacteria enabled us to identify those residues of critical functional importance and revealed a unique sequence signature that is potentially responsible for substrate specificity and catalytic selectivity of C4H.

Sorgum [Sorghum bicolor (L.) Moench] Genomunda BES1 Transkripsiyon Faktör Ailesinin Genom Çaplı Analizi

BES1 transkripsiyon faktörü ailesi brassinosteroidlerin biyosentezinde önemli bir role sahiptir. Bitki büyüme ve gelişmesüreçlerini ve çevresel streslere yanıt mekanizmasını etkileyen bir steroid hormonudur. Bu çalışmanın amacı sorgum[Sorghum bicolor (L.) Moench] bitkisinin farklı dokularında farklı azot kaynakları (kontrol gübresi, amonyak, nitrat, üre)uygulanarak bu dokulardaki BES1 transkripsiyon faktörünün ifade profillerini belirlemek ve in siliko olarak BES1 genailesinin üyelerini genom çapında tespit ederek karakterize etmektir. Sorgum genomunda amino asit sayıları 190 ile 716,moleküler ağırlıkları 35.27 ile 80.54 kDa ve izoelektrik noktaları 5.0 ile 10.07 arasında değişen 9 Sobic-BES1 proteinibelirlenmiştir. Gen yapısı analizlerinde tahmini ekzonların sayısı 2 ile 10 arasında değişmiştir. S. bicolor, Arabidopsisthaliana ve Oryza sativa türlerinin BES1 proteinleri kullanılarak filogenetik ilişki tespit edilmiştir. Evrimsel süreçte Sobic-BES1-4 ve Sobic-BES1-9 genlerinin segmental duplike olduğu belirlenmiştir. İn siliko gen ifade analizlerine göre farklı azotkaynaklarının ve su kontrolünün uygulandığı kök ve sürgün dokularında Sobic-BES1-4 ve -9 genlerinin ifade seviyelerininen yüksek olduğu, diğer taraftan kullanılan azot kaynağına ve dokuya göre Sobic-BES1-1, Sobic-BES1-2 ve Sobic-BES1-8genlerinin ifade seviyelerinin farklılık gösterdiği belirlenmiştir. Bu çalışmanın sonuçları fonksiyonel gen araştırmaları içinbir temel sağlayacak olup, sorgum bitkisinde BES1 gen ailesinin anlaşılmasına katkı sunacaktır.

Phylogenomic Analysis of R2R3 MYB Transcription Factors in Sorghum and their Role in Conditioning Biofuel Syndrome.

Background Large scale cultivation of sorghum for food, feed, and biofuel requires concerted efforts for engineering multipurpose cultivars with optimised agronomic traits. Due to their vital role in regulating the biosynthesis of phenylpropanoid-derived compounds, biomass composition, biotic, and abiotic stress response, R2R3-MYB family transcription factors are ideal targets for improving environmental resilience and economic value of sorghum.Methods We used diverse computational biology tools to survey the sorghum genome to identify R2R3-MYB transcription factors followed by their structural and phylogenomic analysis. We used in-house generated as well as publicly available high throughput expression data to analyse the R2R3 expression patterns in various sorghum tissue types.Results We have identified a total of 134 R2R3-MYB genes from sorghum and developed a framework to predict gene functions. Collating information from the physical location, duplication, structural analysis, orthologous sequences, phylogeny, and expression patterns revealed the role of duplications in clade-wise expansion of the R2R3-MYB family as well as intra-clade functional diversification. Using publicly available and in-house generated RNA sequencing data, we provide MYB candidates for conditioning biofuel syndrome by engineering phenylpropanoid biosynthesis and sugar signalling pathways in sorghum.Conclusion The results presented here are pivotal to prioritize MYB genes for functional validation and optimize agronomic traits in sorghum.

Transcriptome Profiling and Genome-Wide Association Studies Reveal GSTs and Other Defense Genes Involved in Multiple Signaling Pathways Induced by Herbicide Safener in Grain Sorghum.

Herbicide safeners protect cereal crops from herbicide injury by inducing genes and proteins involved in detoxification reactions, such as glutathione S-transferases (GSTs) and cytochrome P450s (P450s). Only a few studies have characterized gene or protein expression profiles for investigating plant responses to safener treatment in cereal crops, and most transcriptome analyses in response to safener treatments have been conducted in dicot model species that are not protected by safener from herbicide injury. In this study, three different approaches were utilized in grain sorghum (Sorghum bicolor (L.) Moench) to investigate mechanisms involved in safener-regulated signaling pathways. An initial transcriptome analysis was performed to examine global gene expression in etiolated shoot tissues of hybrid grain sorghum following treatment with the sorghum safener, fluxofenim. Most upregulated transcripts encoded detoxification enzymes, including P450s, GSTs, and UDP-dependent glucosyltransferases (UGTs). Interestingly, several of these upregulated transcripts are similar to genes involved with the biosynthesis and recycling/catabolism of dhurrin, an important chemical defense compound, in these seedling tissues. Secondly, 761 diverse sorghum inbred lines were evaluated in a genome-wide association study (GWAS) to determine key molecular-genetic factors governing safener-mediated signaling mechanisms and/or herbicide detoxification. GWAS revealed a significant single nucleotide polymorphism (SNP) associated with safener-induced response on chromosome 9, located within a phi-class SbGST gene and about 15-kb from a different phi-class SbGST. Lastly, the expression of these two candidate SbGSTs was quantified in etiolated shoot tissues of sorghum inbred BTx623 in response to fluxofenim treatment. SbGSTF1 and SbGSTF2 transcripts increased within 12-hr after fluxofenim treatment but the level of safener-induced expression differed between the two genes. In addition to identifying specific GSTs potentially involved in the safener-mediated detoxification pathway, this research elucidates a new direction for studying both constitutive and inducible mechanisms for chemical defense in cereal crop seedlings.

THE MAIN WAYS OF INFECTION OF GRAIN SORGHUM BY BURKHOLDERIA ANDROPOGONIS (BURKHOLDERIACEAE, BURKHOLDERIALES) IN THE FOREST-STEPPE OF THE MIDDLE VOLGA REGION

Bacterial leaf stripe, caused by Burkholderia andropogonis, is one of the main sorghum diseases in the forest-steppe of the Middle Volga region. The purpose of the research was to examine the main ways of infection of sorghum by Burkholderia andropogonis. The studies were carried out on experimental fields of the Volga region Scientific Research Institute of Selection and Seed-growing and in the laboratories of Plant Protection and Microbiology of the Samara State Agricultural Academy in 2010-2015. The severity of sorghum leaf stripe in the stage of physiological maturity was 9-60%, with a maximum in high-drought (2010), minimum in wet and cool (2011) years. Losses of grain sorghum yield from B. andropogonis were on average up to 30 %. The main overwintering and primary inoculum sources reported are infested seeds. Up to 97-100 % of the sorghum seeds were infected with B. andropogonis. After sowing infected seeds, bacteria spread through the vascular system in seedlings and developing plants, penetrating into emerging and ripening seeds. The main indirect vector of bacterial leaf stripe is the flea beetle Phyllotreta vittula feeding on sorghum leaves. In the first half of July, adults of the new generation of P. vittula facilitate the penetration of the pathogen from B. andropogonis exudate into the tissues of sorghum through wounds that feeding beetles form on the upper surface of young leaves. The role of flea beetles P. vittula in the spread of the bacteria B andropogonis in crops of sorghum recorded for the first time.