CcNAC6 Acts as a Positive Regulator of Secondary Cell Wall Synthesis in Sudan Grass (Sorghum sudanense S.).

The degree of forage lignification is a key factor affecting its digestibility by ruminants such as cattle and sheep. Sudan grass (Sorghum sudanense S.) is a high-quality sorghum forage, and its lignocellulose is mostly stored in the secondary cell wall. However, the secondary cell wall synthesis mechanism of Sudan grass has not yet been studied in depth. To further study the secondary cell wall synthesis mechanism of Sudan grass using established transcriptome data, this study found that CcNAC6, a homologous gene of Arabidopsis AtSND2, is related to the secondary cell wall synthesis of Sudan grass. Accordingly, we constructed a CcNAC6-overexpressing line of Arabidopsis to investigate the function of the CcNAC6 gene in secondary cell wall synthesis. The results showed that the overexpression of the CcNAC6 gene could significantly increase the lignin content of Arabidopsis. Based on subcellular localization analysis, CcNAC6 is found in the nucleus. In addition, yeast two-hybridization screening showed that CcCP1, associated with secondary cell wall synthesis, can interact with CcNAC6. Therefore, the above results indicate that CcNAC6 has a positive regulatory effect on the secondary cell wall synthesis of Sudan grass, and it is speculated that CcNAC6 may be the main regulator of the secondary cell wall synthesis of Sudan grass through its interaction with another regulatory protein, CcCP1. This study provides a theoretical basis and new genetic resources for the creation of new Sudan grass germplasm with a low lignin content.

CcNAC1 by Transcriptome Analysis Is Involved in Sudan Grass Secondary Cell Wall Formation as a Positive Regulator.

Sudan grass is a high-quality forage of sorghum. The degree of lignification of Sudan grass is the main factor affecting its digestibility in ruminants such as cattle and sheep. Almost all lignocellulose in Sudan grass is stored in the secondary cell wall, but the mechanism and synthesis of the secondary cell wall in Sudan grass is still unclear. In order to study the mechanism of secondary cell wall synthesis in Sudan grass, we used an in vitro induction system of Sudan grass secondary cell wall. Through transcriptome sequencing, it was found that the NAC transcription factor CcNAC1 gene was related to the synthesis of the Sudan grass secondary cell wall. This study further generated CcNAC1 overexpression lines of Arabidopsis to study CcNAC1 gene function in secondary cell wall synthesis. It was shown that the overexpression of the CcNAC1 gene can significantly increase lignin content in Arabidopsis lines. Through subcellular localization analysis, CcNAC1 genes could be expressed in the nucleus of a plant. In addition, we used yeast two-hybrid screening to find 26 proteins interacting with CcNAC1. GO and KEGG analysis showed that CcNAC1 relates to the metabolic pathways and biosynthesis of secondary metabolites. In summary, the synthesis of secondary cell wall of Sudan grass can be regulated by CcNAC1.

Phytoremediation potential of hybrid Pennisetum in cadmium-contaminated soil and its physiological responses to cadmium.

Cadmium (Cd) contamination in soil is a global problem. Recently, phytoremediation with plants, possessing high biomass and moderate Cd enrichment ability, has received excessive attention as a cost-effective method for Cd remediation from the soil. In this study, the plant growth, physiological responses, Cd concentration, accumulation, and distribution of the C4 grass hybrid Pennisetum (HP) were studied in different levels of Cd-contaminated soil in a pot experiment. Furthermore, a field trial was also conducted to accurately assess its practical phytoremediation potential in natural Cd-contaminated fallow filed. The results showed that HP possessed effective antioxidant enzymes to scavenge ROS and strong physiological coordination in response to Cd stress. The HP had a considerable Cd enrichment ability, and the maximal Cd uptake of 1.08 mg plant-1 was achieved at 60 mg kg-1 Cd in the pot. The maximal concentration of Cd in the aboveground parts and roots of HP were 49.33 mg kg-1 and 103.33 mg kg-1, respectively, when soil Cd was 70 mg kg-1 in the pot. The bioconcentration factor (BCF) of Cd in the aboveground parts was less than 1, while the BCF in the root was greater than 1, and the translocation factor (TF) was less than 0.5 in all Cd treatment groups. A total of 46.89-65.46% absorbed Cd stored in the aboveground parts in the pot. The Cd concentration in roots of HP was significantly higher compared to those in leaves and stems, and all BCFs were greater than 1.5 in a lightly Cd-contaminated field (0.35 mg kg-1). Furthermore, HP had high aboveground dry biomass up to 54.63 t ha-1 and accumulated 16.13 g ha-1 Cd in its aboveground parts in the field, which was accounted for about 91.54% of the total Cd extracted by the plant. The soil Cd concentration was reduced by 60.00% after planting HP. Our results suggest that HP is a potential phytoextractor for Cd in lightly Cd-contaminated soil as well as a phytostabilizer under strong Cd stress in the pot.

Evaluation of biological and chemical additives on microbial community, fermentation characteristics, aerobic stability, and in vitro gas production of SuMu No. 2 elephant grass.

BACKGROUND: The study was conducted to evaluate the effects of biological and chemical additives on microbial community, fermentation characteristics, aerobic stability, and in vitro gas production of SuMu No. 2 elephant grass. RESULTS: Aerobic bacteria and yeast were not affected on days 5 and 7 but were significantly (P < 0.224) reduced on days 14, 30, and 60, whereas lactic acid and lactic acid bacteria were significantly (P > 0.001) higher in all ensiling days within all treatment groups. During the ensiling days, the pH, acetic acid, butyric acid, and yeast were decreased in all treatment groups, whereas the Lactobacillus plantarum group and L. plantarum + natamycin group were highly significantly (P > 0.001) decreased. During air exposure, the water-soluble carbohydrates, ammonia nitrogen, lactic acid, and acetic acid were not affected on days 1-4, whereas pH and aerobic bacteria (were significantly (P < 0.05) increased on days 2-4. The addition of Lactobacillus plantarum and natamycin increased the gas production, in vitro dry matter digestibility, and in vitro neutral detergent fiber of SuMu No. 2 elephant grass silages. CONCLUSIONS: The addition of biological and chemical additives, such as L. plantrum alone and the combination with natamycin, affected the undesirable microbial community, fermentation characteristics, aerobic stability, and in vitro gas of SuMu No. 2 elephant grass. © 2021 Society of Chemical Industry.

Improving hybrid Pennisetum growth and cadmium phytoremediation potential by using Bacillus megaterium BM18-2 spores as biofertilizer.

Environmental pollution with heavy metals becomes an issue of serious concern worldwide. Cadmium is considered one which adversely affects living organisms. Recently, the usage of endophytic bacteria to enhance the plant growth and phytoremediation of heavy metals contaminated sites is gaining great attention. The current study focused on utilizing the spores of Bacillus megaterium BM18-2 as biofertilizer for enhancing the growth of Cd hyperaccumulator Hybrid Pennisetum and Cd tolerance of the plant. Therefore, the production of the highest proportion of BM18-2 spores in short incubation time was investigated using different culture media. The results revealed that the maximum proportion of BM18-2 spores (90%) was obtained following incubation for 48 h in Tryptone- yeast extract media (TY). Furthermore, several growth parameters of H. Pennisetum were shown to be significantly improved by inclusion of BM18-2 spores into Cd contaminated soil in contrast to non- inoculated plant. The chlorophyll concentration of the leaves rose by 5%, 13%, and 22.89% with increasing Cd concentration of soil (20, 40 and 60 mg/Kg, respectively). The percentage of total nitrogen content of the root, stem and leaf was increased due to the bacterial spores inoculation and the highest percentage was recorded in the leaf in all treatments. Moreover, Cd phytoremediation capacity of H. Pennisetum greatly enhanced with the application of BM18-2 spores into the soil. An obvious correlation was also observed between Cd accumulation and bacterial colonization where the Cd accumulation enhanced by 21.9%, 16.5%, and 94.6% and the maximum count of BM18-2 (27 × 105, 194 × 104,and 145 × 104 CFU/g) were recorded in the root system in 20, 40, and 60 mg/Kg Cd spiked soil, respectively. Consequently, the spores of BM18-2 was proven to succeed as biofertilizer to improve growth of H. pennisetum during Cd stress which subsequently improved the phytoremediation of Cd contaminated soil.

Ensiling of whole-plant hybrid pennisetum with natamycin and Lactobacillus plantarum impacts on fermentation characteristics and meta-genomic microbial community at low temperature.

BACKGROUND: The aim of the current research was to clarify the impacts of the ensiling of whole-plant hybrid pennisetum with natamycin and Lactobacillus plantarum on fermentation characteristics and the meta-genomic microbial community at low temperatures. RESULTS: During the ensiling process, lactic acid (LA) and lactic acid bacteria (LAB) significantly (P < 0.05) increased and acetic acid (AA), water-soluble carbohydrate (WSC), ammonia total nitrogen (NH3-N), and yeast significantly (P < 0.05) reduced in treatments as compared to controls. Different treatments and different ensiling days led to variations in the bacterial community at family and genus levels. The family Lactobacillaceae and genera Lactobacillus and Pediococcus are dominant communities in treatment silage. The family and genus levels bacterial ecology and fermentation quality were analyzed by principal component analysis (PCA). The PCO1, and PCO2 can be explained by 10.81% and 72.14% of the whole variance regularly, similarly in PCO1 and PCO2 can be explained 24.23% and 52.06% regularly. The core bacterial micro-biome operational taxonomic unit (OTU) numbers increased in treatments, as compared to controls, on different hybrid pennisetum ensiling days. CONCLUSIONS: The inoculation of L. plantarum alone and combined with natamycin influenced the fermentation quality and reduced undesirable microorganisms during the fermentation of hybrid pennisetum silage. Natamycin alone did not significantly enhance the concentration of organic acid but numerically enhanced in treatments group as compared to control. © 2020 Society of Chemical Industry.

Effects of natamycin and Lactobacillus plantarum on the chemical composition, microbial community, and aerobic stability of Hybrid pennisetum at different temperatures.

This study evaluated the effects of natamycin and Lactobacillus plantarum on the chemical composition, microbial community, and aerobic stability of Hybrid pennisetum at different temperatures. Different concentrations of natamycin (0.50 g L-1, 1.00 g L-1, and 1.50 mg L-1) significantly (p > 0.05) reduced the growth of undesirable microorganisms. During the ensiling periods the pH, ammonia nitrogen (NH3-N), acetic acid (AA), butyric acid (BA), aerobic bacteria (AB), and yeast were significantly (p > 0.05) reduced, while the lactic acid and lactic acid bacteria were significantly (p < 0.05) influenced in the SLP and SLNP groups as compared to the SP and SNP groups at high temperature (29-30 °C). During air exposure, water-soluble carbohydrate, ammonia nitrogen (NH3-N), lactic acid (LA), and acetic acid (AA) were not influenced, while pH and aerobic bacteria were significantly (p < 0.05) enhanced after three days (72 hours) of air exposure, and lactic acid bacteria were significantly (p > 0.05) reduced at ambient temperature (9-10 °C). It is concluded that the addition of L. plantarum CICC 20765 alone and in combination with natamycin reduced the content of AA, pH, NH3-N, BA, and undesirable microbial community, and enhanced the chemical composition, fermentation quality, and air exposure. Natamycin alone did not significantly enhance the organic acid profile but improved the air exposure. Furthermore, more effort is needed to evaluate the effects on silage preservation on a large scale and on animal performance.

Effect of endophytic Bacillus megaterium colonization on structure strengthening, microbial community, chemical composition and stabilization properties of Hybrid Pennisetum.

BACKGROUND: This study was conducted to analyze the effects of endophytic Bacillus megaterium (BM 18-2) colonization on structure strengthening, microbial community, chemical composition and stabilization properties of Hybrid Pennisetum. RESULTS: The BM 18-2 had successfully colonized in the interior tissues in both leaf and stem of Hybrid Pennisetum. During ensiling, the levels of pH, acetic acid (AA), butyric acid (BA), propionic acid (PA), and the population of yeast and aerobic bacteria were significantly (P > 0.05) lower, while lactic acid bacteria (LAB) and lactic acid (LA) were significantly (P < 0.001) higher with the steps forward of ensiling in with BM 18-2 as compared to without BM 18-2 colonized of Hybrid Pennisetum. During the different ensiling days, at days 3, 6, 15, and 30, the genus Brevundimonas, Klebsiella, Lactococcus, Weissella, Enterobacter, Serratia, etc. population were significantly decreased, while genus Pediococcus acidilactici and Lactobacillus plantarum were significantly influenced in treated groups as compared to control. The genus Lactobacillus and Pediococcus were positively correlated with treatment groups. CONCLUSIONS: It is concluded that the endophytic bacteria strain BM 18-2 significantly promoted growth characteristics and biomass yield before ensiling and after ensiling inoculated with or without Lactobacillus plantarum could improve the distinct changes of the undesirable microbial diversity, chemical composition, and stabilization properties in with BM 18-2 as compared to without BM 18-2 colonized Hybrid Pennisetum. © 2019 Society of Chemical Industry.

Potential effect of the microbial fermented feed utilization on physicochemical traits, antioxidant enzyme and trace mineral analysis in rabbit meat.

The study investigated the potential effect of the microbial fermented feed utilization on physicochemical traits, antioxidant enzyme and trace mineral analysis in rabbit meat. A total of 72 six-week-old male rabbits were weighed and randomly divided into four groups (1) (SRKC) control; (2) (SRKP) Lactobacillus plantarum 1 × 106  cfu/g fresh weight (FW); (3) (SRKG) Pediococcus acidilactici 1 × 106 cfu/g FW and (4) (SRKPG) P. acidilactici + L. plantarum 1 × 106 cfu/g FW. Performance characteristic, weekly body weight, was positively (p < .05) enhanced, while daily feed intake (DFI) and feed convention ratio (FCR) were not influenced in treatments group as compared to untreated. The water, protein, water holding capacity (WHC) and dry matter (DM) concentration were positively (p < .05) influenced, while ash, pH, lightness, redness and yellowness were not influenced in treated group as compared to untreated. The concentration of glutathione peroxidase (Gpx), superoxide dismutase (SOD) and aspartate aminotransferase (AST) was positively (p < .05) influenced in treatments group as compared to control. Regarding trace minerals, copper (Cu), iron (Fe), manganese (Mn) and zinc (Zn) were positively (p > .05) reduced in treated group as compared to untreated. It is concluded that the addition of lactic acid bacteria (L. plantarum and P. acidilactici) in Hybrid pennisetum silage had a constructive influence on rabbit health performance and meat biochemistry.

Endophytic Bacillus megaterium BM18-2 mutated for cadmium accumulation and improving plant growth in Hybrid Pennisetum.

Hybrid Pennisetum (Pennisetum americanum × P. purpureum Schumach L.) is a tall and rapidly growing perennial C4 bunch grass. It has been considered as a promising plant for phytoremediation of heavy metal-contaminated soil due to its high biomass, high resistance to environmental stress, pests and diseases. Heavy metal bioavailability level is the most important parameter for measurement of the phytoremediation efficiency. Endophytic bacteria were used to further enhance phytoremediation of heavy metals through bioaccumulation or bioabsorption process. In the present study, the endophytic Bacillus megaterium strain 'BM18' isolated from hybrid Pennisetum was screened under 10-70 µM cadmium (Cd) stress for Cd-resistant mutant colonies. And one such mutant colony'BM18-2' was obtained from the screen. Comparably, 'BM18-2' was more Cd-tolerant and had higher Cd removal ability than the original strain'BM18'. The amount of IAA and ammonia production, and phosphate solubilization were 1.09, 1.23 and 1.24 times in 'BM18-2' than those of 'BM18', respectively. Full genome sequencing of these two strains revealed 6 different genes: BM18GM000901, BM18GM005669 and BM18GM005870 encoding heavy metal efflux pumps, BM18GM003487 and BM18GM005818 encoding transcriptional regulators for metal stress biosensor and BM18GM001335 encoding a replication protein. Inoculation with 'BM18-2' or 'BM18' both significantly reduced the toxic effect of Cd on hybrid Pennisetum, while the effect of 'BM18-2' on plant growth promotion in the presence of Cd was significantly better that of 'BM18'. Therefore, the mutated strain 'BM18-2' could be used as a potential agent for Cd bioremediation, improving growth and Cd absorption of hybrid Pennisetum in Cd contaminated soil.

IAA stimulates pollen tube growth and mediates the modification of its wall composition and structure in Torenia fournieri.

The effects of several hormones on pollen tube growth were compared in Torenia fournieri and it was found that IAA was the most effective, stimulating pollen tube growth and causing the shank part of pollen tubes to be slender and straighter. The role of IAA was investigated by studying the changes in ultrastructure and PM H(+)-ATPase distribution in the pollen tubes and the modification of the tube wall. Using the fluorescent marker FM4-64, together with transmission electron microscopy, it was shown that secretory vesicles and mitochondria increased in IAA-treated tubes. Immunolocalization and fluorescence labelling, together with Fourier-transform infrared analysis, detected that IAA enhanced the level of PM H(+)-ATPase and the synthesis of pectins, and reduced the cellulose density in pollen tubes. Importantly, to observe the orientation of cellulose microfibrils in pollen tubes in situ, atomic force microscopy was used to examine the 'intact' tube wall. Atomic force microscopy images showed that cellulose microfibrils were parallel to each other in the subapical region of IAA-treated tubes, but disorganized in control tubes. All results provided new insights into the functions of cellulose microfibrils in pollen tube growth and direction, and revealed that the IAA-induced changes of pollen tubes were attributed to the increase in secretory vesicles, mitochondria, and PM H(+)-ATPase, and the modification of pectin and cellulose microfibrils in the tube wall.