Lysine 2-hydroxyisobutyrylation proteomics analyses reveal the regulatory mechanism of CaMYB61-CaAFR1 module in regulating stem development in Capsicum annuum L.

Plant stems constitute the most abundant renewable resource on earth. The function of lysine (K)-2-hydroxyisobutyrylation (Khib), a novel post-translational modification (PTM), has not yet been elucidated in plant stem development. Here, by assessing typical pepper genotypes with straight stem (SS) and prostrate stem (PS), we report the first large-scale proteomics analysis for protein Khib to date. Khib-modifications influenced central metabolic processes involved in stem development, such as glycolysis/gluconeogenesis and protein translation. The high Khib level regulated gene expression and protein accumulation associated with cell wall formation in the pepper stem. Specially, we found that CaMYB61 knockdown lines that exhibited prostrate stem phenotypes had high Khib levels. Most histone deacetylases (HDACs, e.g., switch-independent 3 associated polypeptide function related 1, AFR1) potentially function as the "erasing enzymes" involved in reversing Khib level. CaMYB61 positively regulated CaAFR1 expression to erase Khib and promote cellulose and hemicellulose accumulation in the stem. Therefore, we propose a bidirectional regulation hypothesis of "Khib modifications" and "Khib erasing" in stem development, and reveal a novel epigenetic regulatory network in which the CaMYB61-CaAFR1 molecular module participating in the regulation of Khib levels and biosynthesis of cellulose and hemicellulose for the first time.

Stem lodging Resistance-1 controls stem strength by positively regulating the biosynthesis of cell wall components in Capsicum annuum L.

Lodging presents a significant challenge in cultivating high-yield crops with extensive above-ground biomass, yet the molecular mechanisms underlying this phenomenon in the Solanaceae family remain largely unexplored. In this study, we identified a gene, CaSLR1 (Capsicum annuum Stem Lodging Resistance 1), which encodes a MYELOBLASTOSIS (MYB) family transcription factor, from a lodging-affected C. annuum EMS mutant. The suppression of CaSLR1 expression in pepper led to notable stem lodging, reduced thickness of the secondary cell wall, and decreased stem strength. A similar phenotype was observed in tomato with the knockdown of SlMYB61, the orthologous gene to CaSLR1. Further investigations demonstrated that CaNAC6, a gene involved in secondary cell wall (SCW) formation, is co-expressed with CaSLR1 and acts as a positive regulator of its expression, as confirmed through yeast one-hybrid, dual-luciferase reporter assays, and electrophoretic mobility shift assays. These findings elucidate the CaNAC6-CaSLR1 module that contributes to lodging resistance, emphasizing the critical role of CaSLR1 in the lodging resistance regulatory network.

Study on land use and landscape pattern change in the Huaihe River Ecological and economic zone from 2000 to 2020.

Exploring the relationship between land use change and landscape patterns can provide a basis for regional ecological management. In this paper, based on remote sensing images of the Huaihe River Ecological and Economic Zone for the years 2000, 2005, 2010, 2015 and 2020, the spatial and temporal evolution patterns of land use in the region were quantitatively described by using the methods of land use shift matrix and landscape pattern analysis. The relationship between land use change and landscape pattern was analyzed with the Grey Relation Analysis (GRA) model. The results show that: (1) the land use of the Huaihe River Ecological and Economic Zone has changed significantly in the past 20 years, with the conversion of arable land into construction and forest lands, in addition to the growth of water areas and a decline in the areas of arable land, grassland and unused land. (2) The landscape pattern fragmentation of each type of land in the study area from 2000 to 2020 fluctuated and decreased, and the landscape connectivity and landscape diversity increased significantly. (3) The GRA model shows that construction, arable and forest lands played the most significant role in the change of landscape pattern of the Huaihe River Ecological and Economic Zone. Countermeasures are proposed to better coordinate and optimize the relationship between spatial development and landscape pattern for the Huaihe River ecological and economic Zone.