Characterization of a splice variant of soybean ERECTA devoid of an intracellular kinase domain in response to shade stress

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.

An improved repertoire of splicing variants and their potential roles in Arabidopsis photomorphogenic development

Background

Light switches on the photomorphogenic development of young plant seedlings, allowing young seedlings to acquire photosynthetic capacities and gain survival fitness. Light regulates gene expression at all levels of the central dogma, including alternative splicing (AS) during the photomorphogenic development. However, accurate determination of full-length (FL) splicing variants has been greatly hampered by short-read RNA sequencing technologies.

Result

In this study, we adopt PacBio isoform sequencing (Iso-seq) to overcome the limitation of the short-read RNA-seq technologies. Normalized cDNA libraries used for Iso-seq allows for comprehensive and effective identification of FL AS variants. Our analyses reveal more than 30,000 splicing variant models from approximately 16,500 gene loci and additionally identify approximately 700 previously unannotated genes. Among the variants, approximately 12,000 represent new gene models. Intron retention (IR) is the most frequently observed form of variants, and many IR-containing AS variants show evidence of engagement in translation. Our study reveals the formation of heterodimers of transcription factors composed of annotated and IR-containing AS variants. Moreover, transgenic plants overexpressing the IR forms of two B-BOX DOMAIN PROTEINs exhibits light-hypersensitive phenotypes, suggesting their regulatory roles in modulating optimal light responses.

Conclusions

This study provides an accurate and comprehensive portrait of full-length transcript isoforms and experimentally confirms the presence of de novo synthesized AS variants that impose regulatory functions in photomorphogenic development in Arabidopsis.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13059-022-02620-2.

The Receptor-Like Kinase ERECTA Confers Improved Water Use Efficiency and Drought Tolerance to Poplar via Modulating Stomatal Density

Poplar is one of the most important tree species in the north temperate zone, but poplar plantations are quite water intensive. We report here that CaMV 35S promoter-driven overexpression of the PdERECTA gene, which is a member of the LRR-RLKs family from Populus nigra × (Populus deltoides × Populus nigra), improves water use efficiency and enhances drought tolerance in triploid white poplar. PdERECTA localizes to the plasma membrane. Overexpression plants showed lower stomatal density and larger stomatal size. The abaxial stomatal density was 24-34% lower and the stomatal size was 12-14% larger in overexpression lines. Reduced stomatal density led to a sharp restriction of transpiration, which was about 18-35% lower than the control line, and instantaneous water use efficiency was around 14-63% higher in overexpression lines under different conditions. These phenotypic changes led to increased drought tolerance. PdERECTA overexpression plants not only survived longer after stopping watering but also performed better when supplied with limited water, as they had better physical and photosynthesis conditions, faster growth rate, and higher biomass accumulation. Taken together, our data suggest that PdERECTA can alter the development pattern of stomata to reduce stomatal density, which then restricts water consumption, conferring enhanced drought tolerance to poplar. This makes PdERECTA trees promising candidates for establishing more water use efficient plantations.