Enhancement of Photosynthetic Capacity in Spongy Mesophyll Cells in White Leaves of Actinidia kolomikta

Repairing Host Damage Caused by Tobacco Mosaic Virus Stress: Design, Synthesis, and Mechanism Study of Novel Oxadiazole and Arylhydrazone Derivatives

Tobacco mosaic virus (TMV), as one of the most traditional and extensive biological stresses, poses a serious threat to plant growth and development. In this work, a series of 1-phenyl/tertbutyl-5-amino-4-pyrazole oxadiazole and arylhydrazone derivatives was synthesized. Bioassay evaluation demonstrated that the title compounds (P1-P18) without a "thioether bond" lost their anti-TMV activity, while some of the ring-opening arylhydrazone compounds exhibited superior in vivo activity against TMV in tobacco. The EC50 value of title compound T8 for curative activity was 139 μg/mL, similar to that of ningnanmycin (NNM) (EC50 = 152 μg/mL). Safety analysis revealed that compound T8 had no adverse effects on plant growth or seed germination at a concentration of 250 μg/mL. Morphological observation revealed that compound T8 could restore the leaf tissue of a TMV-stressed host and the leaf stomatal aperture to normal. A mechanism study further revealed that compound T8 not only restored the photosynthetic and growth ability of the damaged host to normal levels but also enhanced catalase (CAT) activity and reduced the content of malondialdehyde (MDA) and hydrogen peroxide (H2O2) in the damaged host, thereby reducing the oxidation damage to the host. TMV-green fluorescent protein (GFP) experiments further demonstrated that compound T8 not only slowed the transmission speed of TMV in the host but also inhibited its reproduction. All of the experimental results demonstrated that compound T8 could reduce the oxidative damage caused by TMV stress and regulate the photosynthetic ability of the host, achieving the ability to repair damage, to make the plant grow normally.

Regulatory effect of graphene on growth and carbon/nitrogen metabolism of maize (Zea mays L.)

BACKGROUND

Leakage of graphene into the environment has resulted from its increasing use. Although the impact of graphene on ecosystems is already in full swing, information regarding its impact on plants is lacking. In particular, the effects of graphene on plant growth and development vary, and basic information on the regulation of carbon and nitrogen metabolism is missing. In the current study, the way in which graphene (0, 25, 50, 100, and 200 g kg-1 ) affects maize seedlings was studied in terms of morphological and biochemical indicators. The purpose of this study was to understand better how graphene regulates plant carbon and nitrogen metabolism and to understand its interactions with leaf structure and plant growth.

RESULTS

The results showed that 50 g kg-1 graphene increased plant height, stem diameter, leaf area, and dry weight; however, this was inhibited by the high level of graphene (200 g kg-1 ). Further studies indicated that different concentrations of graphene could increase leaf thickness and vascular bundle area as well as the net photosynthetic rate (Pn) of leaves; 25 and 50 g kg-1 graphene enhanced the leaves stomatal conductance (Cond), transpiration rate (Tr), intercellular carbon dioxide (Ci), and chlorophyll content. Higher concentrations decreased the above indicators. At 50 g kg-1 , graphene increased the activity of carbon/nitrogen metabolism enzymes by increasing carbon metabolites (fructose, sucrose, and soluble sugars) and soluble proteins (nitrogen metabolites). These enzymes included sucrose synthase (SS), sucrose phosphate synthase (SPS), nitrate reductase (NR), glutamine synthase (GS), and glutamate synthase (GOGAT).

CONCLUSION

These results indicate that graphene can regulate the activities of key enzymes involved in carbon and nitrogen metabolism effectively and supplement nitrogen metabolism through substances produced by carbon metabolism by improving photosynthetic efficiency, thus maintaining the balance between carbon and nitrogen and promoting plant growth and development. The relationship between these indexes explained the mechanism by which graphene supported the growth of maize seedlings by enhancing photosynthetic carbon metabolism and maintaining metabolic balance. For maize seedling growth, graphene treatment with 50 g kg-1 soil is recommended. © 2023 Society of Chemical Industry.

Cloning of the Soybean GmNHL1 Gene and Functional Analysis under Salt Stress

When encountered in the soybean seedling stage, salt stress has serious impacts on plant growth and development. This study explores the role of the soybean NDR1/HIN1-like family gene GmNHL1 under salt stress. First, the GmNHL1 gene was successfully cloned, and bioinformatic analysis revealed multiple cis-acting elements which are related to adversity stress and involved in the oxidative response in the promoter region. Sub-cellular localization analysis indicated that the protein expressed by GmNHL1 was localized on the cell membrane. An over-expression vector of the target gene and a CRISPR/Cas9 gene-editing vector were constructed, and the recipient soybean variety Jinong 74 was genetically transformed using the Agrobacterium tumefaciens-mediated method. By analyzing the performance of the different plants under salt stress, the results showed that GmNHL1 was over-expressed in the T2 generation. The germination potential, germination rate, germination index, and vitality index of the strain were significantly higher than those of the recipient control JN74. Under salt stress conditions, the root microanatomical structure of the GmNHL1 over-expressing material remained relatively intact, and its growth was better than that of the recipient control JN74. Measurement of physiological and biochemical indicators demonstrated that, compared with the receptor control JN74, the malondialdehyde and O2- contents of the GmNHL1 over-expressing material were significantly reduced, while the antioxidant enzyme activity, proline content, and chlorophyll content significantly increased; however, the results for GmNHL1 gene-edited materials were the opposite. In summary, over-expression of GmNHL1 can improve the salt tolerance of plants and maintain the integrity of the root anatomical structure, thereby more effectively and rapidly reducing the accumulation of malondialdehyde and O2- content and increasing antioxidant enzyme activity. This reduces cell membrane damage, thereby improving the salt tolerance of soybean plants. These results help to better understand the mechanism of salt tolerance in soybean plants, laying a theoretical foundation for breeding new stress-resistant varieties of soybean.

Novel 1,3,4-Thiadiazole Derivatives: Synthesis, Antiviral Bioassay and Regulation the Photosynthetic Pathway of Tobacco against TMV Infection

Tobacco mosaic virus (TMV) is a systemic virus that poses a serious threat to crops worldwide. In the present study, a series of novel 1-phenyl-4-(1,3,4-thiadiazole-5-thioether)-1H-pyrazole-5-amine derivatives was designed and synthesized. In vivo antiviral bioassay results indicated that some of these compounds exhibited excellent protective activity against TMV. Among the compounds, E₂ (EC₅₀ = 203.5 μg/mL) was superior to the commercial agent ningnanmycin (EC₅₀ = 261.4 μg/mL). Observation of tobacco leaves infected with TMV-GFP revealed that E₂ could effectively inhibit the spread of TMV in the host. Further plant tissue morphological observation indicated that E₂ could induce the tight arrangement and alignment of the spongy mesophyll and palisade cells while causing stomatal closure to form a defensive barrier to prevent viral infection in the leaves. In addition, the chlorophyll content of tobacco leaves was significantly increased after treatment with E₂, and the net photosynthesis (Pn) value was also increased, which demonstrated that the active compound could improve the photosynthetic efficiency of TMV-infected tobacco leaves by maintaining stable chlorophyll content in the leaves, thereby protecting host plants from viral infection. The results of MDA and H₂O₂ content determination revealed that E₂ could effectively reduce the content of peroxides in the infected plants, reducing the damage to the plants caused by oxidation. This work provides an important support for the research and development of antiviral agents in crop protection.