Photosynthesis: New light on biological oxygen production

Analysis of the response regulatory network of pepper genes under hydrogen peroxide stress

Hydrogen peroxide (H₂O₂) is a regulatory component related to plant signal transduction. To better understand the genome-wide gene expression response to H₂O₂ stress in pepper plants, a regulatory network of H₂O₂ stress-gene expression in pepper leaves and roots was constructed in the present study. We collected the normal tissues of leaves and roots of pepper plants after 40 days of H₂O₂ treatment and obtained the RNA-seq data of leaves and roots exposed to H₂O₂ for 0.5-24 h. By comparing the gene responses of pepper leaves and roots exposed to H₂O₂ stress for different time periods, we found that the response in roots reached the peak at 3 h, whereas the response in leaves reached the peak at 24 h after treatment, and the response degree in the roots was higher than that in the leaves. We used all datasets for K-means analysis and network analysis identified the clusters related to stress response and related genes. In addition, CaEBS1, CaRAP2, and CabHLH029 were identified through a co-expression analysis and were found to be strongly related to several reactive oxygen species-scavenging enzyme genes; their homologous genes in Arabidopsis showed important functions in response to hypoxia or iron uptake. This study provides a theoretical basis for determining the dynamic response process of pepper plants to H₂O₂ stress in leaves and roots, as well as for determining the critical time and the molecular mechanism of H₂O₂ stress response in leaves and roots. The candidate transcription factors identified in this study can be used as a reference for further experimental verification.

Mobility of Transgenic Nucleic Acids and Proteins within Grafted Rootstocks for Agricultural Improvement

Grafting has been used in agriculture for over 2000 years. Disease resistance and environmental tolerance are highly beneficial traits that can be provided through use of grafting, although the mechanisms, in particular for resistance, have frequently been unknown. As information emerges that describes plant disease resistance mechanisms, the proteins, and nucleic acids that play a critical role in disease management can be expressed in genetically engineered (GE) plant lines. Utilizing transgrafting, the combination of a GE rootstock with a wild-type (WT) scion, or the reverse, has the potential to provide pest and pathogen resistance, impart biotic and abiotic stress tolerance, or increase plant vigor and productivity. Of central importance to these potential benefits is the question of to what extent nucleic acids and proteins are transmitted across a graft junction and whether the movement of these molecules will affect the efficacy of the transgrafting approach. Using a variety of specific examples, this review will report on the movement of organellar DNA, RNAs, and proteins across graft unions. Attention will be specifically drawn to the use of small RNAs and gene silencing within transgrafted plants, with a particular focus on pathogen resistance. The use of GE rootstocks or scions has the potential to extend the horticultural utility of grafting by combining this ancient technique with the molecular strategies of the modern era.