The mitogen-activated protein kinase (MAPK) pathway is a widely distributed signaling cascade in eukaryotes and is involved in regulating plant growth, development, and stress responses. High temperature, a frequently occurring environmental stressor, causes premature bolting in lettuce with quality decline and yield loss. However, whether MAPKs play roles in thermally induced bolting remains poorly understood. In this study, 17 LsMAPK family members were identified from the lettuce genome. The physical and chemical properties, subcellular localization, chromosome localization, phylogeny, gene structure, family evolution, cis-acting elements, and phosphorylation sites of the LsMAPK gene family were evaluated via in silico analysis. According to phylogenetic relationships, LsMAPKs can be divided into four groups, A, B, C, and D, which is supported by analyses of gene structure and conserved domains. The collinearity analysis showed that there were 5 collinearity pairs among LsMAPKs, 8 with AtMAPKs, and 13 with SlMAPKs. The predicted cis-acting elements and potential phosphorylation sites were closely associated with hormones, stress resistance, growth, and development. Expression analysis showed that most LsMAPKs respond to high temperatures, among which LsMAPK4 is significantly and continuously upregulated upon heat treatments. Under heat stress, the stem length of the LsMAPK4-knockdown lines was significantly shorter than that of the control plants, and the microscope observations demonstrated that the differentiation time of flower buds at the stem apex was delayed accordingly. Therefore, silencing of LsMAPK4 significantly inhibited the high- temperature-accelerated bolting in lettuce, indicating that LsMPAK4 might be a potential regulator of lettuce bolting. This study provides a theoretical basis for a better understanding of the molecular mechanisms underlying the MAPK genes in high-temperature-induced bolting.

Maize ((Zea mays L.) is one of the three major grains in the world, widely cultivated globally. Heavy metal Zn pollution poses great risks to corn growth and food security, posing a serious threat to the environment and human health. HMA belongs to the transport protein of the heavy metal ATPase family and can transport Zn²⁺ and Cd²⁺ across membranes. To identify the gene function of maize ZmHMA3 in response to Zn pollution, this study constructed a CRISPR-Cas9 mediated ZmHMA3 knockout mutant, using maize inbred line B104 as the genetic background. Under heavy metal Zn stress, gene specific expression, subcellular localization, agronomic traits, root morphology indicators, antioxidant indicators, and Zn content in various parts and subcellular components of cells were measured. Zmhma3 reduced various growth indicators (plant height, fresh weight, dry weight, and water content) and root morphology indicators of maize, decreased antioxidant enzyme activity, increased membrane permeability, and increased zinc accumulation. Various parameters indicate that under Zn stress, Zmhma3 exhibits weaker tolerance than WT, demonstrating the positive regulatory role of the ZmHMA3 gene in Zn stress. These have laid the foundation for exploring the regulatory mechanisms of plants in response to Zn pollution in the future. Key worlds Maize; HMA; heavy metal pollution; Zn; CRISPR-Caas9; gene function

The primary parts of corn stalks are the leaves and the stems, which comprise the cortex and the pith. Corn has long been cultivated as an grain crops, and now it is a primary global source of sugar, ethanol, and biomass-generated energy. Even though increasing the sugar content in the stalk is an important breeding goal, progress has been modest in many breeding researchers. Accumulation is the gradual rise in quantity when new additions are made. The challenging characteristics of such sugar content in corn stalks are below the protein, bio-economy, and mechanical injury. Hence, in this research, plant water-content-enabled micro-Ribonucleic acids (PWC-miRNAs) were designed to increase the sugar content in corn stalks following an accumulation rule. High-throughput sequencing of the transcriptome, short RNAs, and coding RNAs was performed here; leaf and stem degradation from two early-maturing Corn genotypes revealed new information on miRNA-associated gene regulation in corn during the sucrose accumulation process. For sugar content in corn stalk, PWC-miRNAs were used to establish the application of the accumulation rule for data-processing monitoring throughout. Through simulation, management, and monitoring, the condition is accurately predicted, providing a new scientific and technological means to improve the efficiency of the construction of sugar content in corn stalks. The experimental analysis of PWC-miRNAs outperforms sugar content in terms of performance, accuracy, prediction ratio, and evaluation. This study aims to provide a framework for increasing the sugar content of corn stalk.

High temperatures significantly accelerate the timing of floral transition, namely, bolting and flowering, in lettuce, which results in severe loss of marketable yield. Thus, understanding the genetic regulation of floral transition is of great interest to plant biologists and lettuce breeders. Here, we show that mitogen‐activated protein kinase (LsMAPK6), whose expression and phosphorylation are stimulated by elevated temperatures, plays a positive role in the floral transition. The lsmapk6 mutants exhibit delayed bolting and flowering, whereas LsMAPK6 overexpression accelerates lettuce bolting. LsMAPK6 physically interacts with LsCO. Knockout of LsCO , to a large extent, phenocopies lsmapk6 mutants, strongly indicating that they function in the same genetic pathway. Mechanistically, LsMAPK6 phosphorylates LsCO at residue serine‐258, resulting in the enhanced transcriptional activity and protein stability of LsCO and consequently the activation of LsFT‐mediated flowering signalling pathways, which was confirmed by phospho‐inactive and mimic analyses. Collectively, these findings reveal that the LsMAPK6‐LsCO signalling module fine‐tunes the timing of floral transition upon high temperatures, demonstrating that LsMAPK6 is a potential target for breeding lettuce cultivars adapted to global warming.

Mesotrione is a widely used post-emergence herbicide for maize. The toxicity of mesotrione to maize (especially sweet corn) has been widely reported, and some sweet corn varieties are highly sensitive to mesotrione, which affects subsequent plant growth periods. However, the molecular mechanisms responsible for the differences in susceptibility to mesotrione are not known. By comparing changes in the transcriptome of mesotrione-tolerant line 301 and mesotrione-sensitive line 276 after mesotrione treatment, we found that the genes coding light-harvesting chlorophyll protein complex were induced in 301, and the genes coding loosening cell walls were overrepresented in 276. The net photosynthetic rate, maximum photochemical efficiency of leaf PSII, photochemical quenching of chlorophyll fluorescence, and the electron transport rate were significantly higher in 301 than in 276 after mesotrione treatment, and these effects became more severe as time passed. In addition, oxidative balance was also affected by mesotrione. Compared with 301, SOD, POD, and CAT activities were significantly reduced with longer exposure time in 276. The results suggested that sweet corn can mitigate herbicide mesotrione toxicity by improving photosynthesis, ROS scavenging, and cell wall synthesis.