Identification and expression analysis of ERECTA family genes in grape (Vitis vinifera L.)

Overexpression of StERECTA enhances drought tolerance in Arabidopsis thaliana

Drought is a major abiotic stresses that severely hinder plant growth and agricultural productivity. The receptor-like kinase gene, ERECTA, has been proved to play important role in promoting the response to abiotic stress in crops. However, the specific molecular mechanisms underlying the drought resistance mediated by ERECTA in potato (Solanum tuberosum L.) are not well understood. In this study, sequence analysis confirmed that the StERECTA gene contains eight leucine-rich repeat (LRR) domains and an S_TKc domain, and these domains were highly conserved in Solanaceae family. Under drought stress, Arabidopsis thaliana strains overexpressing StERECTA showed increased biomass, proline (PRO) content, and antioxidant enzyme activities compared to the wild-type strains while the mutant ERECTA strain (er105) exhibited opposite phenotype. Additionally, StERECTA overexpression upregulated the expression of drought response marker genes (LEA3, DREB2A and P5CS1), improved levels of ABA and auxin, reduced stomatal density and relative expression level of stomatal development related genes (SPCH, FAMA and MUTE). Furthermore, Co-immunoprecipitation (Co-IP) assays demonstrated that StERECTA physically interacted with the YODA protein. In conclusion, our study provides new insights into the role and regulatory mechanism of StERECTA in response to drought stress. These findings may serve as a basis for genetic improvement of potato to enhance their tolerance to abiotic stress.

Receptor-like kinase ERECTA negatively regulates anthocyanin accumulation in grape

Receptor-like kinase (ERECTA, ER) is essential for mediating growth, development, and stress response signaling pathway in plants. In this study, we investigated the effect of VvER on anthocyanin synthesis as a regulatory factor in transgenic grape callus in response to chilling stress. Results showed that overexpression of VvER reduced the expression of transcription factors VvMYBA1, VvMYB5b, VvMYC2, and VvWDR1, as well as the structural genes VvCHS, VvCHI, VvDFR, VvLDOX, and VvUFGT, and inhibited the anthocyanins synthesis of grape callus at 25℃. VvER reduced proline content and antioxidant enzymes activities of superoxide dismutase (SOD) and peroxidase (POD), and inhibited the expression of anthocyanin synthesis genes to reduce the cold resistance of grape callus. In transgenic Arabidopsis, overexpression of VvER promoted the elongation of Arabidopsis rosettes and sprigs. Under strong light treatment, VvER inhibited the accumulation of anthocyanins in Arabidopsis; Transient expression in strawberry fruit showed that VvER inhibited the synthesis of anthocyanin in strawberry fruit by inhibiting the expression of FaCHI, FaCHS, FaDFR and FaUFGT under low temperature treatment at 10°C, but not under the normal temperature of 25℃. Using Yeast two-hybrid, we found that VvER interacted with transcription factor proteins including VvMYBA1, VvMYB5b and VvWDR1. Furthermore, VvER led to the repression of VvUFGT promoter activity and decreased the anthocyanin biosynthesis genes expression by downregulation MBW complex activity. Totally, VvER could inhibit anthocyanin biosynthesis and involve in the grape plant susceptible to cold stress for grape cultivation in northern China.

Overexpression of forage millet (Setaria italica) SiER genes enhances drought resistance of Arabidopsis thaliana

ERECTA (ER) is a type of receptor-like kinase that contributes a crucial mission in various aspects of plant development, physiological metabolism, and abiotic stresses responses. This study aimed to explore the functional characteristics of the SiER family genes in millet (Setaria italica L.), focusing on the growth phenotype and drought resistance of Arabidopsis overexpressed SiER4_X1 and SiER1_X4 genes (SiERs ). The results revealed that overexpression of SiER4_X1 and SiER1_X4 genes in Arabidopsis significantly enhanced the leaf number, expanded leaf length and width, further promoted the silique number, length and diameter, and plant height and main stem thickness, ultimately leading to a substantial increase in individual plant biomass. Compared to the wild-type (WT), through simulated drought stress, the expression level of SiER genes was notably upregulated, transgenic Arabidopsis seeds exhibited stronger germination rates and root development; after experiencing drought conditions, the activities of antioxidant enzymes (superoxide dismutase and peroxidase) increased, while the levels of malondialdehyde and relative electrical conductivity decreased. These results indicate that overexpression of SiERs significantly enhanced both biomass production and drought resistance in Arabidopsis . The SiER4_X1 and SiER1_X4 genes emerge as promising candidate genes for improving biomass production and drought resistance in forage plants.

Enhanced biomass and thermotolerance of Arabidopsis by SiERECTA isolated from Setaria italica L

Foxtail millet is commonly used as a food and forage grass. ERECTA (ER) is a receptor-like kinase that can improve plant biomass and stress resistance. The sorghum SbER10_X1 gene was used as a probe to identify ER family genes on the Setaria italica genomes (SiERs), and determine the characteristics of the SiERs family. Herein, the structural features, expression patterns, and thermotolerance of SiERs function were identified by bioinformatics analysis, real-time PCR and transgenesis estimation. Results showed that SiERs had four members: two members were located on chromosome 1 with a total of six copies (SiER1_X1, SiER1_X2, SiER1_X3, SiER1_X4, SiER1_X5, and SiER1_X6), and two were on chromosome 4, namely, SiER4 (SiER4_X1 and SiER4_X2) and SiERL1. Among them, SiER1_X4 and SiER4_X1 were expressed highest in above-ground organs of foxtail millet, and actively responded to treatments with abscisic acid, brassinolide, gibberellin, and indole acetic acid. After overexpression of SiER1_X4 and SiER4_X1 in Arabidopsis, the plant height and biomass of the transgenic Arabidopsis significantly increased. Following high-temperature treatment, transgenic seedlings survived better compared to wild type. Transgenic lines showed higher SOD and POD activities, and expression level of AtHSF1 and AtBl1 genes significantly increased. These results indicated that SiER1_X4 and SiER4_X1 played important regulatory roles in plant growth and thermotolerance. The two genes provide potential targets for conventional breeding or biotechnological intervention to improve the biomass of forage grass and thermotolerance of field crops.

Effect of Climate on Volatile Metabolism in 'Red Globe' Grapes (Vitis vinifera L.) during Fruit Development

With unique flavor and nutritional value, grapes are popular for eating and for the byproducts obtained in their processing. This study cultivated a popular grape variety, ‘Red Globe’, in two regions with different climates to investigate the discrepancies in their volatiles in response to climate. Saccharides, organic acids and transcriptomic and volatile metabolic analyses were studied separately via GC-FID, RNA sequencing and GC-MS/MS methods during the development of grape berries. In total, 83 volatiles were determined in samples, with (E)-2-hexenal the most abundant. Fatty acid derivatives and terpenoids in grapes showed discrepancies in different climates, and some of them were correlated to specific transcription factors. VvWRKY22 was influenced by climate conditions and was relative to saccharide accumulation. MYB-related transcription factors (TFs) were highly correlated with volatiles that accumulated during fruit ripening, especially decanal. Terpenoids showed correlations with a gene module that contained ERFs and HSFs. The findings support the hypothesis that fruit maturity and volatile formations vary in grape berries under different climates. Moreover, specific TFs could participate in volatile accumulations. The given results not only serve to enrich theoretical knowledge on the regulatory mechanism of volatiles in grapes, but also provide guidance for enhancing grape flavor and aroma by modulating cultivational conditions.

Melon short internode (CmSi) encodes an ERECTA-like receptor kinase regulating stem elongation through auxin signaling

Plant height is one of the most important agronomic traits that directly determines plant architecture, and compact or dwarf plants can allow for increased planting density and land utilization as well as increased lodging resistance and economic yield. At least four dwarf/semidwarf genes have been identified in different melon varieties, but none of them have been cloned, and little is known about the molecular mechanisms underlying internode elongation in melon. Here, we report map-based cloning and functional characterization of the first semidwarf gene short internode (Cmsi) in melon, which encodes an ERECTA-like receptor kinase regulating internode elongation. Spatial-temporal expression analyses revealed that CmSI exhibited high expression in the vascular bundle of the main stem during internode elongation. The expression level of CmSI was positively correlated with stem length in the different melon varieties examined. Ectopic expression of CmSI in Arabidopsis and cucumber suggested CmSI as a positive regulator of internode elongation in both species. Phytohormone quantitation and transcriptome analysis showed that the auxin content and the expression levels of a number of genes involved in the auxin signaling pathway were altered in the semidwarf mutant, including several well-known auxin transporters, such as members of the ABCB family and PIN-FORMED genes. A melon polar auxin transport protein CmPIN2 was identified by protein-protein interaction assay as physically interacting with CmSI to modulate auxin signaling. Thus, CmSI functions in an auxin-dependent regulatory pathway to control internode elongation in melon. Our findings revealed that the ERECTA family gene CmSI regulates stem elongation in melon through auxin signaling, which can directly affect polar auxin transport.