[The research progress in determining lignocellulosic content by near infrared reflectance spectroscopy technology].

Near infrared reflectance spectroscopy technology, as a new analytic method, can be used to determine the content of lignin, cellulose and hemi-cellulose which is faster, effective, easier to operate, and more accurate than the traditional wet chemical methods. Nowadays it has been widely used in measuring the composition of lignocelluloses in woody plant and herbaceous plant. The domestic and foreign research progress in determining the lignin, cellulose and hemi-cellulose content in woody plant ( wood and bamboo used as papermaking raw materials and wood served as potential biomass energy) and herbaceous plant (forage grass and energy grass) by near infrared reflectance spectroscopy technology is comprehensively summarized and the advances in method studies of measuring the composition of lignocelluloses by near infrared reflectance spectroscopy technology are summed up in three aspects, sample preparation, spectral data pretreatment and wavelength selection methods, and chemometric analysis respectively. Four outlooks are proposed combining the development statues of wood, forage grass and energy grass industry. First of all, the authors need to establish more feasible and applicable models for a variety of uses which can be used for more species from different areas, periods and anatomical parts. Secondly, comprehensive near infrared reflectance spectroscopy data base of grass products quality index needs to be improved to realize on-line quality and process control in grassproducts industry, which can guarantee the quality of the grass product. Thirdly, the near infrared reflectance spectroscopy quality index model of energy plant need to be built which can not only contribute to breed screening, but also improve the development of biomass industry. Besides, modeling approaches are required to be explored and perfected any further. Finally, the authors need to try our best to boost the advancement in the determination method of lignin, cellulose and hemi-cellulose by near infrared reflectance spectroscopy from the laboratory to the practical applications. Along with the method of determining the lignin, cellulose and hemi-cellulose by near infrared spectroscopy being unceasingly perfected and matured, this technique will actively have a positive effect on the development of papermaking, forage grass and energy grass industry.

Proline improves switchgrass growth and development by reduced lignin biosynthesis.

Transgenic switchgrass overexpressing Lolium perenne L. delta1-pyrroline 5-carboxylate synthase (LpP5CS) in group I (TG4 and TG6 line) and group II (TG1 and TG2 line) had significant P5CS and ProDH enzyme activities, with group I plants (TG4 and TG6) having higher P5CS and lower ProDH enzyme activity, while group II plants had higher ProDH and lower P5CS enzyme activity. We found group II transgenic plants showed stunted growth, and the changed proline content in overexpressing transgenic plants may influence the growth and development in switchgrass. RNA-seq analysis showed that KEGG enrichment included phenylpropanoid biosynthesis pathway among group I, group II and WT plants, and the expression levels of genes related to lignin biosynthesis were significantly up-regulated in group II. We also found that lignin content in group II transgenic plants was higher than that in group I and WT plants, suggesting that increased lignin content may suppress switchgrass growth and development. This study uncover that proline can appropriately reduce lignin biosynthesis to improve switchgrass growth and development. Therefore, appropriate reduction in lignin content and increase in biomass are important for bioenergy crop to lower processing costs for biomass fermentation-derived fuels.

PvNAC1 increases biomass and enhances salt tolerance by decreasing Na+ accumulation and promoting ROS scavenging in switchgrass (Panicum virgatum L.).

Switchgrass (Panicum virgatum L.) is a bioenergy crop; thus, it is important to improve biomass to effectively produce bioethanol, particularly under adverse stress conditions. NAC transcription factors are involved in the abiotic stress response. PvNAC1 was isolated in the nucleus of switchgrass, with its C-terminal region containing a transcriptional activation domain. PvNAC1 expression was induced by dehydration, salt, H2O2, and abscisic acid treatments. Overexpressing (OE) PvNAC1 improved growth performance, leading to significantly taller and heavier (dry weight) plants. Moreover, cellulose content was significantly higher in OE plants, indicating that PvNAC1 plays an important role regulating growth and bioethanol production. PvNAC1 RNA interference (RNAi) switchgrass plants exhibited reduced dry weight and cellulose content. OE PvNAC1 enhanced tolerance to salt stress, through higher reactive oxygen species scavenging ability and less Na+ and more K+ accumulation in roots and shoots. RNAi plants were more sensitive to salt stress. The quantitative polymerase chain reaction results revealed that some stress responsive genes, three antioxidant enzymatic genes, and an ion homeostasis-related gene were upregulated in OE plants and downregulated in RNAi plants. These results show that PvNAC1 functions as a transcriptional activator in response to salt stress and growth.

Evaluation of processing technology for Triarrhena sacchariflora (Maxim.) Nakai for ethanol production.

The effects of dilute H2SO4 concentration, forage:sulfuric acid ratio, digestion time, and digestion temperature were evaluated to determine effects on ethanol yield of Triarrhena sacchariflora (Maxim.) Nakai. Twenty single factor experiments were conducted to evaluate H2SO4 concentration (0.5, 1.0, 1.5, 2.0, and 2.5%, w/w), forage:sulfuric acid ratio (1:6, 1:8, 1:10, 1:12, and 1:14, g/ml), digestion time (15, 30, 45, 60, and 90, min), digestion temperature (80, 100, 110, 120, and 125 °C) for 3 replicates of the 5 levels of each factor. Based on results of the single factor experiments, an incomplete factorial was designed to evaluate ethanol yield from the best combinations of single factors. Finally, the best combination was tested by enzymatic hydrolysis and fermentation experiment in selected combinations according to pretreatment results. Percentage cellulose, hemicellulose, and lignin contents of forage residue after pretreatment, and glucose and xylose concentrations of the filtrate were analyzed prior to enzymatic hydrolysis, and percentage crystallinity was observed in untreated grass and pretreated residue. In addition, the solid residues were then hydrolysed and fermented by cellulase and yeast, the concentrations of glucose and ethanol being monitored for 96 h. Results showed that the order of the effect of main effect factors was as follows: digestion temperature > dilute H2SO4 concentration > digestion time > forage:sulfuric acid ratio. The best process parameters evaluated were sulfuric acid concentration of 1.5%, forage:sulfuric acid ratio of 1:6, digestion time of 15 min, and digestion temperature of 120°C. With this combination of factors, 80% of the cellulose was hydrolysed in 96 h, and 78% converted to ethanol. The findings identified that hemicelluloses were the key deconstruction barrier for pretreatment of Triarrhena sacchariflora (Maxim.) Nakai for ethanol production. The results of this research provide evidence of appropriate combinations of processing factors for production of ethanol from Triarrhena sacchariflora (Maxim.) Nakai.

Enhanced anticancer activity of glutamate prodrugs of all-trans retinoic acid.

OBJECTIVES: All-trans retinoic acid (ATRA), an active metabolite of vitamin A, is widely used in the treatment of acute promyelocytic leukaemia and myelodysplastic syndrome. However, its high lipophilicity is thought to be responsible for the slow dissolution and low bioavailability following oral administration. In order to obtain compounds with better solubility characteristics to improve the transportation and bioavailability of ATRA, derivatives of ATRA containing glutamic acid or its sodium salt were synthesised. METHODS: The ATRA derivatives synthesised - all-trans retinoyl glutamate (RAE) and all-trans retinoyl sodium glutamate (RAENa(2)) - were characterised in terms of melting point, optical rotation, mass spectrometry, NMR and partition coefficient. A liposomal preparation formed from RAE was characterised by particle size and zeta potential. The anti-tumour activity of RAE and RAENa(2) was compared with that of ATRA in mice bearing S(180) tumours and their effects on the cell cycle were determined in human pro-myelocytic leukaemia HL-60 cells. KEY FINDINGS: RAE and RAENa(2) were more active than ATRA against tumour growth. Flow cytometry indicated that RAE and RAENa(2) induced HL-60 cell cycle arrest, similar to ATRA. DNA fragmentation studies suggested that apoptosis may be one of the mechanisms responsible for the anti-tumour activities. CONCLUSIONS: The two derivatives of ATRA, RAE and RAENa(2), exhibited improved aqueous solubility and were more effective in mice bearing S(180) tumours.