Identification of leucine-rich repeat receptor-like protein kinase (LRR-RLK) genes in paper mulberry and their potential roles in response to cold stress

Genome-Wide Transcriptional Profiling and Functional Analysis Reveal That OsPHT4;4 Is Critical for the Growth and Development of Rice

Phosphorus (P) is an essential macronutrient required for various vital processes in crop growth and development, including signal transduction, CO2 fixation, and photosynthetic phosphorylation. Phosphate transporters (PHTs) in plants play critical roles in the uptake, distribution, and internal transport of Phosphate (Pi). Among these transporters, the PHT4 family is widely distributed across plant species; however, the specific functions of many members within this family remain to be fully elucidated. This study focuses on unraveling the function of OsPHT4;4 in Pi utilization and photoprotection. The findings demonstrate that OsPHT4;4 acts as a low-affinity Pi transporter localized to the chloroplast membrane and reveal predominant expression of OsPHT4;4 in leaves, with peak expression during tillering and clear induction by light, exhibiting circadian rhythmicity. The ospht4;4 mutants display stunted growth. Transcriptomic analysis comparing ospht4;4 mutants and wild-types (WT) identified 1482 differentially expressed genes (DEGs), including 729 upregulated genes and 753 downregulated genes. Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analysis reveals enrichment DEGs related to photosynthesis-antenna proteins, carbohydrate metabolism, and phenylpropanoid biosynthesis. These findings suggest that OsPHT4;4 plays crucial roles not only in photosynthesis but also in plant defense as an integral component involved in Pi metabolism.

Emerging Roles of Receptor-like Protein Kinases in Plant Response to Abiotic Stresses

The productivity of plants is hindered by unfavorable conditions. To perceive stress signals and to transduce these signals to intracellular responses, plants rely on membrane-bound receptor-like kinases (RLKs). These play a pivotal role in signaling events governing growth, reproduction, hormone perception, and defense responses against biotic stresses; however, their involvement in abiotic stress responses is poorly documented. Plant RLKs harbor an N-terminal extracellular domain, a transmembrane domain, and a C-terminal intracellular kinase domain. The ectodomains of these RLKs are quite diverse, aiding their responses to various stimuli. We summarize here the sub-classes of RLKs based on their domain structure and discuss the available information on their specific role in abiotic stress adaptation. Furthermore, the current state of knowledge on RLKs and their significance in abiotic stress responses is highlighted in this review, shedding light on their role in influencing plant-environment interactions and opening up possibilities for novel approaches to engineer stress-tolerant crop varieties.

Genome-wide analysis and characterization of the LRR-RLK gene family provides insights into anthracnose resistance in common bean

Anthracnose, caused by the hemibiotrophic fungus Colletotrichum lindemuthianum, is a damaging disease of common beans that can drastically reduce crop yield. The most effective strategy to manage anthracnose is the use of resistant cultivars. There are many resistance loci that have been identified, mapped and associated with markers in common bean chromosomes. The Leucine-rich repeat kinase receptor protein (LRR-RLK) family is a diverse group of transmembrane receptors, which potentially recognizes pathogen-associated molecular patterns and activates an immune response. In this study, we performed in silico analyses to identify, classify, and characterize common bean LRR-RLKs, also evaluating their expression profile in response to the infection by C. lindemuthianum. By analyzing the entire genome of Phaseolus vulgaris, we could identify and classify 230 LRR-RLKs into 15 different subfamilies. The analyses of gene structures, conserved domains and motifs suggest that LRR-RLKs from the same subfamily are consistent in their exon/intron organization and composition. LRR-RLK genes were found along the 11 chromosomes of the species, including regions of proximity with anthracnose resistance markers. By investigating the duplication events within the LRR-RLK family, we associated the importance of such a family with an expansion resulting from a strong stabilizing selection. Promoter analysis was also performed, highlighting cis-elements associated with the plant response to biotic stress. With regard to the expression pattern of LRR-RLKs in response to the infection by C. lindemuthianum, we could point out several differentially expressed genes in this subfamily, which were associated to specific molecular patterns of LRR-RLKs. Our work provides a broad analysis of the LRR-RLK family in P. vulgaris, allowing an in-depth structural and functional characterization of genes and proteins of this family. From specific expression patterns related to anthracnose response, we could infer a direct participation of RLK-LRR genes in the mechanisms of resistance to anthracnose, highlighting important subfamilies for further investigations.

Cold adaptation strategies in plants—An emerging role of epigenetics and antifreeze proteins to engineer cold resilient plants

Cold stress adversely affects plant growth, development, and yield. Also, the spatial and geographical distribution of plant species is influenced by low temperatures. Cold stress includes chilling and/or freezing temperatures, which trigger entirely different plant responses. Freezing tolerance is acquired via the cold acclimation process, which involves prior exposure to non-lethal low temperatures followed by profound alterations in cell membrane rigidity, transcriptome, compatible solutes, pigments and cold-responsive proteins such as antifreeze proteins. Moreover, epigenetic mechanisms such as DNA methylation, histone modifications, chromatin dynamics and small non-coding RNAs play a crucial role in cold stress adaptation. Here, we provide a recent update on cold-induced signaling and regulatory mechanisms. Emphasis is given to the role of epigenetic mechanisms and antifreeze proteins in imparting cold stress tolerance in plants. Lastly, we discuss genetic manipulation strategies to improve cold tolerance and develop cold-resistant plants.