Systematic Analysis of the BrHAT Gene Family and Physiological Characteristics of Brassica rapa L. Treated with Histone Acetylase and Deacetylase Inhibitors under Low Temperature.

Brassica rapa L. is an important overwintering oilseed crop in Northwest China. Histone acetyltransferases (HATs) play an important role in epigenetic regulation, as well as the regulation of plant growth, development, and responses to abiotic stresses. To clarify the role of histone acetylation in the low-temperature response of B. rapa L., we identified 29 HAT genes in B. rapa L. using bioinformatics tools. We also conducted a comprehensive analysis of the physicochemical properties, gene structure, chromosomal localization, conserved structural domains and motifs, cis-acting regulatory elements, and evolutionary relationships of these genes. Using transcriptome data, we analyzed the expression patterns of BrHAT family members and predicted interactions between proteins; the results indicated that BrHATs play an important role in the low-temperature response of B. rapa L. HAT inhibitor (curcumin; CUR) and histone deacetylase inhibitor (Trichostatin A; TSA) were applied to four B. rapa L. varieties varying in cold resistance under the same low-temperature conditions, and changes in the physiological indexes of these four varieties were analyzed. The inhibitor treatment attenuated the effect of low temperature on seed germination, and curcumin treatment was most effective, indicating that the germination period was primarily regulated by histone acetylase. Both inhibitor treatments increased the activity of protective enzymes and the content of osmoregulatory substances in plants, suggesting that histone acetylation and deacetylation play a significant role in the response of B. rapa L. to low-temperature stress. The qRT-PCR analyses showed that the expression patterns of BrHATs were altered under different inhibitor treatments and low-temperature stress; meanwhile, we found three significantly differentially expressed genes. In sum, the process of histone acetylation is involved in the cold response and the BrHATs gene plays a role in the cold stress response.

Fast and Selective Degradation of Biomass for Xylose, Glucose and Lignin under Mild Conditions.

The conversion of lignocellulose into valuable chemicals has been recognized as the key technology in green chemistry. However, selective degradation of hemicellulose and cellulose with the production of lignin is still a challenge. Therefore, a two-step process has been developed to degrade corncob into xylose and glucose under mild conditions. At first, the corncob was treated with the lower concentration of zinc chloride aqueous solution (30-55 w%) at 95 °C with a short reaction time (8-12 min) and 30.4 w% (selectivity = 89%) of xylose obtained with a solid residue of the composite of cellulose and lignin. Next, the solid residue was treated with a high concentration of zinc chloride aqueous solution (65-85 w%) at 95 °C for about 10 min, and 29.4 w% (selectivity = 92%) of glucose can be obtained. Combining the two steps, the total yield of xylose is 97%, while glucose is 95%. In addition, high pure lignin can be obtained simultaneously, which was confirmed using HSQC studies. Furthermore, for the solid residue of the first-step reaction, a ternary deep eutectic solvent (DES) (choline chloride/oxalic acid/1,4-butanediol, ChCl/OA/BD) has been used to separate the cellulose and lignin efficiently, and high-quality cellulose (Re-C) and lignin (Re-L) were obtained. Furthermore, it provides a simple method to disassemble the lignocellulose for monosaccharides, lignin, and cellulose.