YTH Domain Proteins Play an Essential Role in Rice Growth and Stress Response

Discovering novel genomic regions explaining adaptation of bread wheat to conservation agriculture through GWAS

To sustainably increase wheat yield to meet the growing world population's food demand in the face of climate change, Conservation Agriculture (CA) is a promising approach. Still, there is a lack of genomic studies investigating the genetic basis of crop adaptation to CA. To dissect the genetic architecture of 19 morpho-physiological traits that could be involved in the enhanced adaptation and performance of genotypes under CA, we performed GWAS to identify MTAs under four contrasting production regimes viz., conventional tillage timely sown (CTTS), conservation agriculture timely sown (CATS), conventional tillage late sown (CTLS) and conservation agriculture late sown (CALS) using an association panel of 183 advanced wheat breeding lines along with 5 checks. Traits like Phi2 (Quantum yield of photosystem II; CATS:0.37, CALS: 0.31), RC (Relative chlorophyll content; CATS:55.51, CALS: 54.47) and PS1 (Active photosystem I centers; CATS:2.45, CALS: 2.23) have higher mean values in CA compared to CT under both sowing times. GWAS identified 80 MTAs for the studied traits across four production environments. The phenotypic variation explained (PVE) by these QTNs ranged from 2.15 to 40.22%. Gene annotation provided highly informative SNPs associated with Phi2, NPQ (Quantum yield of non-photochemical quenching), PS1, and RC which were linked with genes that play crucial roles in the physiological adaptation under both CA and CT. A highly significant SNP AX94651261 (9.43% PVE) was identified to be associated with Phi2, while two SNP markers AX94730536 (30.90% PVE) and AX94683305 (16.99% PVE) were associated with NPQ. Identified QTNs upon validation can be used in marker-assisted breeding programs to develop CA adaptive genotypes.

Genome-Wide Identification and Expression Analysis of YTH Gene Family for Abiotic Stress Regulation in Camellia chekiangoleosa

N6-methyladenosine (m6A) is essential for RNA metabolism in cells. The YTH domain, conserved in the kingdom of Eukaryotes, acts as an m6A reader that binds m6A-containing RNA. In plants, the YTH domain is involved in plant hormone signaling, stress response regulation, RNA stability, translation, and differentiation. However, little is known about the YTH genes in tea-oil tree, which can produce edible oil with high nutritional value. This study aims to identify and characterize the YTH domains within the tea-oil tree (Camellia chekiangoleosa Hu) genome to predict their potential role in development and stress regulation. In this study, 10 members of the YTH family containing the YTH domain named CchYTH1-10 were identified from C. chekiangoleosa. Through analysis of their physical and chemical properties and prediction of subcellular localization, it is known that most family members are located in the nucleus and may have liquid-liquid phase separation. Analysis of cis-acting elements in the CchYTH promoter region revealed that these genes could be closely related to abiotic stress and hormones. The results of expression profiling show that the CchYTH genes were differentially expressed in different tissues, and their expression levels change under drought stress. Overall, these findings could provide a foundation for future research regarding CchYTHs in C. chekiangoleosa and enrich the world in terms of epigenetic mark m6A in forest trees.

Transcriptome-Wide N6-Methyladenosine (m6A) Methylation Analyses in a Compatible Wheat-Puccinia striiformis f. sp. tritici Interaction

N6-methyladenosine (m6A) is a prevalent internal modification in eukaryotic mRNA, tRNA, miRNA, and long non-coding RNA. It is also known for its role in plant responses to biotic and abiotic stresses. However, a comprehensive m6A transcriptome-wide map for Puccinia striiformis f. sp. tritici (Pst) infections in wheat (Triticum aestivum) is currently unavailable. Our study is the first to profile m6A modifications in wheat infected with a virulent Pst race. Analysis of RNA-seq and MeRIP-seq data revealed that the majority of differentially expressed genes are up-regulated and hyper-methylated. Some of these genes are enriched in the plant-pathogen interaction pathway. Notably, genes related to photosynthesis showed significant down-regulation and hypo-methylation, suggesting a potential mechanism facilitating successful Pst invasion by impairing photosynthetic function. The crucial genes, epitomizing the core molecular constituents that fortify plants against pathogenic assaults, were detected with varying expression and methylation levels, together with a newly identified methylation motif. Additionally, m6A regulator genes were also influenced by m6A modification, and their expression patterns varied at different time points of post-inoculation, with lower expression at early stages of infection. This study provides insights into the role of m6A modification regulation in wheat's response to Pst infection, establishing a foundation for understanding the potential function of m6A RNA methylation in plant resistance or susceptibility to pathogens.

Exploring N6-methyladenosine (m6A) modification in tree species: opportunities and challenges

N 6-methyladenosine (m6A) in eukaryotes is the most common and widespread internal modification in mRNA. The modification regulates mRNA stability, translation efficiency, and splicing, thereby fine-tuning gene regulation. In plants, m6A is dynamic and critical for various growth stages, embryonic development, morphogenesis, flowering, stress response, crop yield, and biomass. Although recent high-throughput sequencing approaches have enabled the rapid identification of m6A modification sites, the site-specific mechanism of this modification remains unclear in trees. In this review, we discuss the functional significance of m6A in trees under different stress conditions and discuss recent advancements in the quantification of m6A. Quantitative and functional insights into the dynamic aspect of m6A modification could assist researchers in engineering tree crops for better productivity and resistance to various stress conditions.

Genome-wide identification, characterization, and expression analysis of m6A readers-YTH domain-containing genes in alfalfa

Eukaryotic messenger RNAs (mRNAs) are often modified with methyl groups at the N6 position of adenosine (m6A), and these changes are interpreted by YTH domain-containing proteins to regulate the metabolism of m6A-modified mRNAs. Although alfalfa (Medicago sativa) is an established model organism for forage development, the understanding of YTH proteins in alfalfa is still limited. In the present investigation, 53 putative YTH genes, each encoding a YT521 domain-containing protein, were identified within the alfalfa genome. These genes were categorized into two subfamilies: YTHDF (49 members) and YTHDC (four members). Each subfamily demonstrates analogous motif distributions and domain architectures. Specifically, proteins encoded by MsYTHDF genes incorporate a single domain structure, while those corresponding to MsYTH5, 8, 12, 16 who are identified as members of the MsYTHDC subfamily, exhibit CCCH-type zinc finger repeats at their N-termini. It is also observed that the predicted aromatic cage pocket that binds the m6A residue of MsYTHDC consists of a sequence of two tryptophan residues and one tyrosine residue (WWY). Conversely, in MsYTHDF, the binding pocket comprises two highly conserved tryptophan residues and either one tryptophan residue (WWW) or tyrosine residue (WWY) in MsYTHDF.Through comparative analysis of qRT-PCR data, we observed distinct expression patterns in specific genes under abiotic stress, indicating their potential regulatory roles. Notably, five genes (MsYTH2, 14, 26, 27, 48) consistently exhibit upregulation, and two genes (MsYTH33, 35) are downregulated in response to both cold and salt stress. This suggests a common mechanism among these YTH proteins in response to various abiotic stressors in alfalfa. Further, integrating qRT-PCR with RNA-seq data revealed that MsYTH2, MsYTH14, and MsYTH16 are highly expressed in leaves at various development stages, underscoring their potential roles in regulating the growth of these plant parts. The obtained findings shed further light on the biological functions of MsYTH genes and may aid in the selection of suitable candidate genes for future genetic enhancement endeavors aimed at improving salt and cold tolerance in alfalfa.