Ming Zhong

Cold stress severely limits the productivity of maize, especially in Northeast China. Hydroxymethylbutenyl diphosphate synthase (HDS) is a key enzyme in the methylerythritol phosphate (MEP) pathway, which is responsible for the generation of precursors for carotenoid biosynthesis, thereby playing a central role in facilitating the cellular response to stress. In the present study, virus-induced gene silencing (VIGS)-mediated ZmHDS1 silencing on the B73 background led to enhanced cold stress sensitivity, as evidenced by growth retardation, leaf shriveling, disrupted Kranz anatomy, elevated reactive oxygen species (ROS) accumulation, impaired antioxidant enzyme activity, increased membrane lipid peroxidation, and reduced photosynthetic performance. Hormonal profiling revealed that ZmHDS1 silencing decreased the content of indole-3-acetic acid (IAA), gibberellin (GA₄), and abscisic acid (ABA) and disrupted ABA signaling. Furthermore, ZmHDS1 silencing reduced the chlorophyll content, Rubisco activity, and ZmRCA (Rubisco activase) expression and caused a more severe reduction in carotenoid levels and the transcriptional suppression of the entire carotenoid biosynthetic gene network. Collectively, ZmHDS1 acts as a key component of the MEP pathway that contributes to maize cold tolerance by coordinating antioxidant defense, phytohormone homeostasis, photosynthetic maintenance, and carotenoid metabolism. These findings highlight the importance of the MEP pathway as a whole in cold adaptation. Disruption of ZmHDS1 impairs these interconnected protective mechanisms, rendering maize highly susceptible to cold-induced damage.

Drought stress critically constrains plant development and morphogenesis, representing a substantial challenge to crop production systems. Dehydrins (DHNs), belonging to the late embryogenesis abundant (LEA) protein superfamily, play crucial roles in plant adaptation to environmental stress conditions. Nevertheless, the capacity of Suaeda salsa SsDHN protein to confer drought resistance has not been adequately investigated. In the present study, transgenic tobacco lines with constitutive SsDHN expression (SsDHN-OE) were employed to examine its influence on seedling development under water-limited conditions. Results indicated that constitutive SsDHN expression enhanced biomass accumulation, foliar expansion, root elongation, and root surface dimensions in water-stressed seedlings. Moreover, transformed lines demonstrated elevated proline (Pro) accumulation and abscisic acid (ABA) content, augmented antioxidant enzyme activity, and intensified stomatal regulation under stress conditions. Conversely, photoinhibition intensity, chloroplast structural degradation, malondialdehyde (MDA) accumulation, electrolyte leakage, hydrogen peroxide (H₂O₂), and superoxide radical (O₂⁻) concentrations were diminished. Furthermore, transcript abundance of stress-responsive genes—encompassing NtNCED3, NtSnRK2.2, NtRD26, NtLEA5, NtPOD, NtSOD, NtCAT, and NtAPX1—was markedly increased in SsDHN-OE lines experiencing drought stress. Taken together, these findings establish that SsDHN functions as a positive regulator of drought resilience in plants.

Jacalin-related lectins (JRLs), a newly discovered subfamily of plant lectins, play an important role in plant growth and development and abiotic stress response. However, in the most important model and economic plant, the tomato, little is known about this gene family. Here, we conducted a genome-wide identification and characterization of the JRL gene family in tomato. A total of eight JRL gene family members (SlJRL1–SlJRL8) were identified based on the tomato genome through bioinformatics analyses, which were unevenly distributed on four chromosomes. Chromosomal localization revealed four pairs of tandemly duplicated genes. Genome collinearity analyses showed that tomato JRL genes were more closely related to Arabidopsis than to rice and maize. Phylogenetic analysis showed that tomato JRL could be divided into seven subgroups, and members within each subgroup shared similar gene structures and conserved motifs. Promoter analysis revealed abundant cis-acting elements associated with stress-responsive and phytohormone-responsive. Finally, real-time quantitative polymerase chain reaction (qRT-PCR) was used to analyze the expression profile of SlJRL gene under various plant hormone and abiotic stress treatments. The results show that the SlJRL gene family exhibits tissue-specific expression patterns and responds to a variety of hormonal and stress conditions. This study systematically analyzed the genomic characteristics of tomato JRL family. Our results lay the foundation for further studies on the biological functions of tomato JRL genes.

Salt stress is a major abiotic stress that interferes with plant growth and affects crop production. Dehydrin (DHN), a member of the late embryogenesis abundant (LEA) protein family, was considered to be a stress protein involved in the protective reaction of plant dehydration. Our previous research has shown that overexpression of the Suaeda salsa SsDHN gene enhances tolerance to salt stress in tobacco. However, the research on its protection in photosynthesis under salt stress remains unclear. In this study, gene overexpression (SsDHN-OE) tobacco plants were utilized to study the effect of the SsDHN gene on plant photosynthesis under salt stress. Our findings showed that overexpression of SsDHN increased the biomass, leaf area, root length, and root surface area in tobacco seedlings under salt stress conditions. The transgenic tobacco with overexpression of SsDHN had obvious stomatal closure, which effectively alleviated the adverse effects of salt stress on photosynthetic efficiency. Overexpression of the SsDHN gene in tobacco can effectively reduce the degree of photoinhibition and chloroplast damage caused by salt stress. Moreover, the SsDHN-overexpressing transgenic tobacco plants exhibited a decrease in oxidative damage and protected membrane structures related to photosynthesis by increasing antioxidant enzyme activity and antioxidant substance content. It was further found that the expression levels of photosynthetic and antioxidant-related genes Rubisco, SBPase, POD7, CAT3, APX2, and SOD3 were significantly up-regulated by overexpressing the SsDHN gene in tobacco seedlings under salt stress. In conclusion, the SsDHN gene might improve the salt stress resistance of tobacco seedlings and be involved in regulating photosynthesis and antioxidant activity under salt stress.

Key message CRISPR/Cas9-mediated knockout of SlWOX4 gene in tomato enhances tolerance to drought stress. Abstract Drought stress is one of the major abiotic factors that seriously affects plant growth and crop yield. WUSCHEL-related homeobox (WOX) transcription factors are involved in plant growth, development and stress response. However, little is known about the role of WOX genes in drought tolerance in tomato. Here, SlWOX4, a member of the WOX family in tomato, was functionally characterized in mediating drought tolerance. SlWOX4 was homologous to Nicotiana tabacum NtWOX4 with a conserved HD domain, and was localized in the nucleus. SlWOX4 was significantly down-regulated by drought and abscisic acid (ABA) treatments. The loss-of-function mutations of SlWOX4 produced using the CRISPR–Cas9 system in tomato improved drought tolerance by reducing water loss rate and enhancing stomatal closure. In addition, the wox4 lines exhibited reduced accumulation of reactive oxygen species (ROS) and malondialdehyde (MDA), increased antioxidant enzyme activity, proline contents and ABA contents under drought stress. Moreover, gene editing of SlWOX4 in tomato enhanced drought tolerance by regulating the expression of genes encoding antioxidants and ABA signaling molecules. In summary, SlWOX4 gene might negatively regulate drought stress tolerance in tomato and has great potential as a drought-resistant crop-breeding target genes.

The domain of unknown function 668 (DUF668) is a gene family that may play a key role in plant growth and development as well as in responding to adversity coercion stresses. However, the DUF668 gene family has not yet been well identified and characterized in tomato. In this study, a total of nine putative SlDUF668 genes were identified in tomato, distributed on six chromosomes. Phylogenetic analyses revealed that SlDUF668 proteins were classified into two major groups. Members within the same group largely displayed analogous gene structure and conserved motif compositions. Several cis-elements were exhibited in the upstream sequences of the SlDUF668 genes, including elements implicated in plant growth and development processes, abiotic stress and hormone responses. Further, the study assessed the expression patterns of the SlDUF668 gene family in various tomato tissues, five plant hormones treatments, three abiotic stresses using qRT-PCR. The SlDUF668 genes expressed ubiquitously in various tissues, and five genes (SlDUF668-04, SlDUF668-06, SlDUF668-07, SlDUF668-08 and SlDUF668-09) showed tissue specificity. And SlDUF668 genes responded to abiotic stresses such as salt, drought and cold to varying degrees. Overall, our study provided a base for the tomato DUF668 gene family and laid a foundation for further understanding the functional characteristics of DUF668 genes in tomato plants.

Remorin (REMs) are plant-specific and plasma membrane-associated proteins that play an essential role in the growth and development of plants and adaptations to adverse environments. To our knowledge, a genome-scale investigation of the REM genes in tomato has never been systematically studied. In this study, a total of 17 SlREM genes were identified in the tomato genome using bioinformatics methods. Our results demonstrated that the 17 members of SlREM were classified into 6 groups based on phylogenetic analysis and unevenly distributed on the eight chromosomes of tomato. There were 15 REM homologous gene pairs between tomato and Arabidopsis. The SlREM gene structures and motif compositions were similar. Promoter sequence analysis showed that the SlREM gene promoters contained some tissue-specific, hormones and stress-related cis-regulatory elements. Expression analysis based on qRT-PCR (Real-time quantitative PCR) analysis showed that SlREM family genes were were differentially expressed in different tissues, and they responded to ABA, MeJA, SA, low-temperature, drought and NaCl treatments. These results potentially provide relevant information for further research on the biological functions of SlREM family genes.

Introduction: β-Mannanase is a plant cell wall remodeling enzyme involved in the breakdown of hemicellulose and plays an important role in growth by hydrolyzing the mannan-like polysaccharide, but its function in adaptation to salt stress has been less studied.Methods: Based on cloned the mannanase (MAN) gene from Mirabilis jalapa L., the study was carried out by heterologously expressing the gene in Arabidopsis thaliana, and then observing the plant phenotypes and measuring relevant physiological and biochemical indicators under 150 mM salt treatment.Results and discussion: The results indicate that MirMAN is a protein with a glycohydrolase-specific structural domain located in the cell wall. We first found that MirMAN reduced the susceptibility of transgenic Arabidopsis thaliana to high salt stress and increased the survival rate of plants by 38%. This was corroborated by the following significant changes, including the reduction in reactive oxygen species (ROS) levels, increase in antioxidant enzyme activity, accumulation of soluble sugars and increase of the expression level of RD29 in transgenic plants. We also found thatthe heterologous expression of MirMAN promoted root growth mainly by elongating the primary roots and increasing the density of lateral roots. Meanwhile, the expression of ARF7, ARF19, LBD16 and LBD29 was up-regulated in the transgenic plants, and the concentration of IAA in the roots was increased. Those results indicate that MirMAN is involved in the initiation of lateral root primordia in transgenic plants through the IAA-ARF signalling pathway. In conclusion, MirMAN improves plant salt tolerance not only by regulating ROS homeostasis, but also by promoting the development of lateral roots. Reflecting the potential of the MirMAN to promote root plastic development in adaptation to salt stress adversity.