Search Results (8)

LEA_1 domain-containing proteins constitute a class of late-embryogenesis-abundant proteins that are highly hydrophilic and predominantly accumulate in mature seeds. Though LEA_1 proteins have been proven to be essential for seed desiccation tolerance and longevity, little information is available on their roles in non-seed storage organs. In this study, a first genome-wide characterization of the LEA_1 gene family was conducted in tigernut (Cyperus esculentus L., Cyperaceae), whose underground tubers are desiccation tolerant with a moisture content of less than 6%. Five family members identified in tigernut are comparative to four to six found in seven other Cyperaceae plants, but relatively more than three reported in Arabidopsis. Further comparison of 125 members from 29 plant species supports early divergence of the LEA_1 family into two phylogenetic groups before angiosperm radiation, and gene expansion in tigernut was contributed by whole-genome duplications occurring after the split with the eudicot clade. These two phylogenetic groups could be further divided into six orthogroups in the momocot clade, five of which are present in tigernut and the remaining one is Poaceae specific. Frequent structural variation and expression divergence of paralogs were also observed. Significantly, in contrast to seed-preferential expression of LEA_1 genes in Arabidopsis, rice, and maize, transcriptional profiling and qRT-PCR analysis revealed that CeLEA1 genes have evolved to predominantly express in tubers, exhibiting a seed desiccation-like accumulation during tuber development. Moreover, CeLEA1 transcripts in tubers were shown to be considerably more than that of their orthologs in purple nutsedge, another Cyperaceae plant producing desiccation-sensitive tubers. These results imply species-specific activation and key roles of CeLEA1 genes in the acquisition of desiccation tolerance of tigernut tubers as observed in orthodox seeds. Our findings not only improve the understanding of lineage-specific evolution of the LEA_1 family, but also provide valuable information for further functional analysis and genetic improvement in tigernut. Full article

The Ethylene Response Factor (ERF) transcription factors form a subfamily of the AP2/ERF family that is instrumental in mediating plant responses to diverse abiotic stressors. Herein, we present the isolation and characterization of the GmERF105 gene from Williams 82 (W82), which is rapidly induced by salt, drought, and abscisic acid (ABA) treatments in soybean. The GmERF105 protein contains an AP2 domain and localizes to the nucleus. GmERF105 was selectively bound to GCC-box by gel migration experiments. Under salt stress, overexpression of GmERF105 in Arabidopsis significantly reduced seed germination rate, fresh weight, and antioxidant enzyme activity; meanwhile, sodium ion content, malonic dialdehyde (MDA) content, and reactive oxygen species (ROS) levels were markedly elevated compared to the wild type. It was further found that the transcription levels of CSD1 and CDS2 of two SOD genes were reduced in OE lines. Furthermore, the GmERF105 transgenic plants displayed suppressed expression of stress response marker genes, including KIN1, LEA14, NCED3, RD29A, and COR15A/B, under salt treatment. Our findings suggest that GmERF105 can act as a negative regulator in plant salt tolerance pathways by affecting ROS scavenging systems and the transcription of stress response marker genes. Full article

The capability of a plant to protect itself from stress-related damages is termed “adaptability” and the phenomenon of showing better performance in subsequent stress is termed “stress memory”. While drought is one of the most serious disasters to result from climate change, the current understanding of drought stress priming in soybean is still inadequate for effective crop improvement. To fill this gap, in this study, the drought memory response was evaluated in cultivated soybean (Glycine max). To determine if a priming stress prior to a drought stress would be beneficial to the survival of soybean, plants were divided into three treatment groups: the unprimed group receiving one cycle of stress (1S), the primed group receiving two cycles of stress (2S), and the unstressed control group not subjected to any stress (US). When compared with the unprimed plants, priming led to a reduction of drought stress index (DSI) by 3, resulting in more than 14% increase in surviving leaves, more than 13% increase in leaf water content, slight increase in shoot water content and a slower rate of loss of water from the detached leaves. Primed plants had less than 60% the transpiration rate and stomatal conductance compared to the unprimed plants, accompanied by a slight drop in photosynthesis rate, and about a 30% increase in water usage efficiency (WUE). Priming also increased the root-to-shoot ratio, potentially improving water uptake. Selected genes encoding late embryogenesis abundant (LEA) proteins and MYB, NAC and PP2C domain-containing transcription factors were shown to be highly induced in primed plants compared to the unprimed group. In conclusion, priming significantly improved the drought stress response in soybean during recurrent drought, partially through the maintenance of water status and stronger expression of stress related genes. In sum, we have identified key physiological parameters for soybean which may be used as indicators for future genetic study to identify the genetic element controlling the drought stress priming. Full article

The dehydration-responsive element-binding protein (DREB) is a subgroup member of the AP2/ERF family and actively participates in the response of plants to abiotic stress. Although DREB genes have been studied in a variety of plant species, there are few reports of DREB genes in sugarcane (Saccharum spp.). In this study, a novel full-length cDNA sequence of the ScDREB2B-1 gene was cloned from the Saccharum hybrid ROC22, whose encoding protein contained only one AP2-conserved domain and was clustered into the DREB (A-2) subgroup. The diverse promoter elements in the ScDREB2B-1 gene and the accumulated transcripts of its homologous gene (SsAP2/ERF-107) in S. spontaneum under drought stress suggest that the ScDREB2B-1 gene may play a role in drought response. In addition, reverse transcription quantitative PCR analysis showed that the expression level of the ScDREB2B-1 gene was upregulated in the root and leaf of ROC22 under polyethylene glycol, sodium chloride and abscisic acid (ABA) treatments. The yeast two-hybrid experiment demonstrated that ScDREB2B-1 had transcriptional self-activation activity. Compared with wild-type plants, the overexpression of the ScDREB2B-1 gene improved the drought tolerance of the transgenic Nicotiana benthamiana by activating the ABA pathway to enhance the expression of the ABA-responsive gene (NbNCED) and ABA content, regulate the intracellular reactive oxygen species (ROS) level (enhance the transcripts of ROS synthase-related gene NbRbohB and the activities of catalase, peroxidase and superoxide dismutase) and increase the relative water content, proline content and expression level of osmotic stress-related genes (NbERD and NbLEA). Collectively, our data indicate that ScDREB2B-1 is a stress-inducible and ABA-responsive transcription factor gene that responds to drought stress by regulating ABA signaling, ROS levels and stress-related gene expression. This study contributes to a better understanding of the biological function of ScDREB2B-1, which could serve as a foundation for future resistance breeding in sugarcane. Full article

Ramonda serbica Panc. is an ancient resurrection plant able to survive a long desiccation period and recover metabolic functions upon watering. The accumulation of protective late embryogenesis abundant proteins (LEAPs) is a desiccation tolerance hallmark. To propose their role in R. serbica desiccation tolerance, we structurally characterised LEAPs and evaluated LEA gene expression levels in hydrated and desiccated leaves. By integrating de novo transcriptomics and homologues LEAP domains, 318 R. serbica LEAPs were identified and classified according to their conserved motifs and phylogeny. The in silico analysis revealed that hydrophilic LEA4 proteins exhibited an exceptionally high tendency to form amphipathic α-helices. The most abundant, atypical LEA2 group contained more hydrophobic proteins predicted to fold into the defined globular domains. Within the desiccation-upregulated LEA genes, the majority encoded highly disordered DEH1, LEA1, LEA4.2, and LEA4.3 proteins, while the greatest portion of downregulated genes encoded LEA2.3 and LEA2.5 proteins. While dehydrins might chelate metals and bind DNA under water deficit, other intrinsically disordered LEAPs might participate in forming intracellular proteinaceous condensates or adopt amphipathic α-helical conformation, enabling them to stabilise desiccation-sensitive proteins and membranes. This comprehensive LEAPs structural characterisation is essential to understanding their function and regulation during desiccation aiming at crop drought tolerance improvement. Full article

Most late embryogenesis abundant group 3 (G3LEA) proteins are highly hydrophilic and disordered, which can be transformed into ordered α-helices to play an important role in responding to diverse stresses in numerous organisms. Unlike most G3LEA proteins, DosH derived from Dinococcus radiodurans is a naturally ordered G3LEA protein, and previous studies have found that the N-terminal domain (position 1–103) of DosH protein is the key region for its folding into an ordered secondary structure. Synthetic biology provides the possibility for artificial assembling ordered G3LEA proteins or their analogues. In this report, we used the N-terminal domain of DosH protein as module A (named DS) and the hydrophilic domains (DrHD, BnHD, CeHD, and YlHD) of G3LEA protein from different sources as module B, and artificially assembled four non-natural hydrophilic proteins, named DS + DrHD, DS + BnHD, DS + CeHD, and DS + YlHD, respectively. Circular dichroism showed that the four hydrophile proteins were highly ordered proteins, in which the α-helix contents were DS + DrHD (56.1%), DS + BnHD (53.7%), DS + CeHD (49.1%), and DS + YLHD (64.6%), respectively. Phenotypic analysis showed that the survival rate of recombinant Escherichia coli containing ordered hydrophilic protein was more than 10% after 4 h treatment with 1.5 M NaCl, which was much higher than that of the control group. Meanwhile, in vivo enzyme activity results showed that they had higher activities of superoxide dismutase, catalase, lactate dehydrogenase and less malondialdehyde production. Based on these results, the N-terminal domain of DosH protein can be applied in synthetic biology due to the fact that it can change the order of hydrophilic domains, thus increasing stress resistance. Full article

Seed dormancy and germination are key events in plant development and are critical for crop production, and defects in seed germination or the inappropriate release of seed dormancy cause substantial losses in crop yields. Rice is the staple food for more than half of the world’s population, and preharvest sprouting (PHS) is one of the most severe problems in rice production, due to a low level of seed dormancy, especially under warm and damp conditions. Therefore, PHS leads to yield loss and a decrease in rice quality and vitality. We reveal that mutation of OsbZIP09 inhibited rice PHS. Analysis of the expression of OsbZIP09 and its encoded protein sequence and structure indicated that OsbZIP09 is a typical bZIP transcription factor that contains conserved bZIP domains, and its expression is induced by ABA. Moreover, RNA sequencing (RNA-seq) and DNA affinity purification sequencing (DAP-seq) analyses were performed and 52 key direct targets of OsbZIP09 were identified, including OsLOX2 and Late Embryogenesis Abundant (LEA) family genes, which are involved in controlling seed germination. Most of these key targets showed consistent changes in expression in response to abscisic acid (ABA) treatment and OsbZIP09 mutation. The data characterize a number of key target genes that are directly regulated by OsbZIP09 and contribute to revealing the molecular mechanism that underlies how OsbZIP09 controls rice seed germination. Full article

Plant growth and development depends on its ability to maintain optimal cellular homeostasis during abiotic and biotic stresses. Cleistogenes songorica, a xerophyte desert plant, is known to have novel drought stress adaptation strategies and contains rich pools of stress tolerance genes. Proteins encoded by Late Embryogenesis Abundant (LEA) family genes promote cellular activities by functioning as disordered molecules, or by limiting collisions between enzymes during stresses. To date, functions of the LEA family genes have been heavily investigated in many plant species except perennial monocotyledonous species. In this study, 44 putative LEA genes were identified in the C. songorica genome and were grouped into eight subfamilies, based on their conserved protein domains and domain organizations. Phylogenetic analyses indicated that C. songorica Dehydrin and LEA_2 subfamily proteins shared high sequence homology with stress responsive Dehydrin proteins from Arabidopsis. Additionally, promoter regions of CsLEA_2 or CsDehydrin subfamily genes were rich in G-box, drought responsive (MBS), and/or Abscisic acid responsive (ABRE) cis-regulatory elements. In addition, gene expression analyses indicated that genes from these two subfamilies were highly responsive to heat stress and ABA treatment, in both leaves and roots. In summary, the results from this study provided a comprehensive view of C. songorica LEA genes and the potential applications of these genes for the improvement of crop tolerance to abiotic stresses. Full article