CaSnRK2.4-mediated phosphorylation of CaNAC035 regulates abscisic acid synthesis in pepper (Capsicum annuum L.) responding to cold stress.

Plant NAC transcription factors play a crucial role in enhancing cold stress tolerance, yet the precise molecular mechanisms underlying cold stress remain elusive. In this study, we identified and characterized CaNAC035, an NAC transcription factor isolated from pepper (Capsicum annuum) leaves. We observed that the expression of the CaNAC035 gene is induced by both cold and abscisic acid (ABA) treatments, and we elucidated its positive regulatory role in cold stress tolerance. Overexpression of CaNAC035 resulted in enhanced cold stress tolerance, while knockdown of CaNAC035 significantly reduced resistance to cold stress. Additionally, we discovered that CaSnRK2.4, a SnRK2 protein, plays an essential role in cold tolerance. In this study, we demonstrated that CaSnRK2.4 physically interacts with and phosphorylates CaNAC035 both in vitro and in vivo. Moreover, the expression of two ABA biosynthesis-related genes, CaAAO3 and CaNCED3, was significantly upregulated in the CaNAC035-overexpressing transgenic pepper lines. Yeast one-hybrid, Dual Luciferase, and electrophoretic mobility shift assays provided evidence that CaNAC035 binds to the promoter regions of both CaAAO3 and CaNCED3 in vivo and in vitro. Notably, treatment of transgenic pepper with 50 µm Fluridone (Flu) enhanced cold tolerance, while the exogenous application of ABA at a concentration of 10 µm noticeably reduced cold tolerance in the virus-induced gene silencing line. Overall, our findings highlight the involvement of CaNAC035 in the cold response of pepper and provide valuable insights into the molecular mechanisms underlying cold tolerance. These results offer promising prospects for molecular breeding strategies aimed at improving cold tolerance in pepper and other crops.

Fabrication of composite hydrogels by sonication-assisted assembly of okara cellulose nanofibers and chitosan: structure and properties.

BACKGROUND: Okara cellulose is a highly abundant, green, sustainable, and biodegradable polymer with many potential industrial applications. In this study, we fabricated composite hydrogels with okara cellulose nanofibers (CNFs) and chitosan (CH) by hydrating, sonicating, and heating them at 100 °C for 30 min, and then induced their assembly by cooling. The effects of okara CNF (with and without 2,2,6,6-tetramethylpiperidinyloxy (TEMPO) oxidation) and CH concentration on the structure and properties of the hydrogels was examined, including their microstructure, surface properties, rheological properties, and thermal stability. RESULTS: Our results indicate that there was an electrostatic attraction between the anionic okara CNF and cationic CH, which facilitated hydrogel formation. The surface, textural, rheological, and thermal stability properties were better for the composite hydrogels than for the single CH ones, as well as for the CNF that had undergone TEMPO oxidation. For the TC-CH hydrogels, the contact angle was 39.5°, the interfacial tension was 69.1 mN m-1 , and the surface tension was 1.44 mN m-1 . CONCLUSION: In this study, the novel hydrogels developed may be useful as a soft material in a range of applications in foods, supplements, health care products, cosmetics, and drugs. © 2023 Society of Chemical Industry.

Composite hydrogels formed from okara cellulose nanofibers and carrageenan: Fabrication and characterization.

Currently, there is great interest in converting edible agro-waste, such as okara from soybean production, into value-added products. For this study, we focus on fabricating composite hydrogels from okara cellulose nanofibers (CNFs) and carrageenan (CA). We also examined the effects of TEMPO oxidation of the okara CNFs, as well as CA concentration, on the microstructure and physicochemical properties of the composite hydrogels. The water holding capacity, oil holding capacity, surface tension, gel strength, and viscoelasticity of the composite microgels increased with increasing CA concentration, and it was found that the highest values were obtained for TC-CA2 hydrogel: contact angle = 43.6° and surface tension = 45.12 mN/m, which was attributed to the formation of a more regular and dense three-dimensional gel network. All the CNF-CA microgels had highly anionic ζ-potential values (-38.8 to -50.1 mV), with the magnitude of the negative charge increasing with TEMPO oxidation and carrageenan concentration. These results suggest there would be strong electrostatic repulsion between the composite hydrogels. The composite microgels produced in our work may be useful functional materials for utilization within the food industry, thereby converting a waste product into a valuable commodity.

Measurement of Linear Springs' Stiffness Factor Using Ultrasonic Sensing.

We designed an ultrasonic testing instrument that consisted of a single-chip microcomputer module, a digital display module, and an ultrasonic sensor module, which conveniently eliminated the troubles faced by the traditional Jolly's scale. For comparison purpose, three linear springs' stiffness factors were measured by Jolly's scale and by our ultrasonic testing instrument. We found that our instrument could more conveniently and in real time display the distance values between the ultrasonic ranging module and the horizontal bottom plate when loading different weights. By processing these distance data, we found that our instrument was more convenient for obtaining the linear springs' stiffness factors and that the results were more accurate than those of Jolly's scale. This study verified that our instrument can accurately realize the performance of Jolly's scale under diverse temperatures and humidity levels with high data reliability and perfect stability.