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DNA methylation is a highly conserved epigenetic modification involved in many biological processes, including growth and development, stress response, and secondary metabolism. DNA demethylase (DNA-deMTase) genes have been identified in some plant species; however, there are no reports on the identification and analysis of DNA-deMTase genes in Foxtail millet (Setaria italica L.). In this study, seven DNA-deMTases were identified in S. italica. These DNA-deMTase genes were divided into four subfamilies (DML5, DML4, DML3, and ROS1) by phylogenetic and gene structure analysis. Further analysis shows that the physical and chemical properties of these DNA-deMTases proteins are similar, contain the typical conserved domains of ENCO3c and are located in the nucleus. Furthermore, multiple cis-acting elements were observed in DNA-deMTases, including light responsiveness, phytohormone responsiveness, stress responsiveness, and elements related to plant growth and development. The DNA-deMTase genes are expressed in all tissues detected with certain tissue specificity. Then, we investigated the abundance of DNA-deMTase transcripts under abiotic stresses (cold, drought, salt, ABA, and MeJA). The results showed that different genes of DNA-deMTases were involved in the regulation of different abiotic stresses. In total, our findings will provide a basis for the roles of DNA-deMTase in response to abiotic stress. [ABSTRACT FROM AUTHOR]

In the ovules of most sexually reproducing plants, one hypodermal cell differentiates into a megaspore mother cell (MMC), which gives rise to the female germline. Trans -acting small interfering RNAs known as tasiR-ARFs have been suggested to act non-cell-autonomously to prevent the formation of multiple MMCs by repressing AUXIN RESPONSE FACTOR3 (ARF3) expression in Arabidopsis (Arabidopsis thaliana), but the underlying mechanisms are unknown. Here, we examined tasiR-ARF-related intercellular regulatory mechanisms. Expression analysis revealed that components of the tasiR-ARF biogenesis pathway are restricted to distinct ovule cell types, thus limiting tasiR-ARF production to the nucellar epidermis. We also provide data suggesting tasiR-ARF movement along the mediolateral axis into the hypodermal cells and basipetally into the chalaza. Furthermore, we used cell type-specific promoters to express ARF3m , which is resistant to tasiR-ARF regulation, in different ovule cell layers. ARF3m expression in hypodermal cells surrounding the MMC, but not in epidermal cells, led to a multiple-MMC phenotype, suggesting that tasiR-ARFs repress ARF3 in these hypodermal cells to suppress ectopic MMC fate. RNA sequencing analyses in plants with hypodermally expressed ARF3m showed that ARF3 potentially regulates MMC specification through phytohormone pathways. Our findings uncover intricate spatial restriction of tasiR-ARF biogenesis, which together with tasiR-ARF mobility enables cell-cell communication in MMC differentiation. [ABSTRACT FROM AUTHOR]

This study identified 57 basic leucine zipper (bZIP) genes from the pineapple genome, and the analysis of these bZIP genes was focused on the evolution and divergence after multiple duplication events in relation to the pineapple genome fusion. According to bioinformatics analysis of a phylogenetic tree, the bZIP gene family was divided into 11 subgroups in pineapple, Arabidopsis, and rice; gene structure and conserved motif analyses showed that bZIP genes within the same subgroup shared similar intron-exon organizations and motif composition. Further synteny analysis showed 17 segmental duplication events with 27 bZIP genes. The study also analyzed the pineapple gene expression of bZIP genes in different tissues, organs, and developmental stages, as well as in abiotic stress responses. The RNA-sequencing data showed that AcobZIP57 was upregulated in all tissues, including vegetative and reproductive tissues. AcobZIP28 and AcobZIP43 together with the other 25 bZIP genes did not show high expression levels in any tissue. Six bZIP genes were exposed to abiotic stress, and the relative expression levels were detected by quantitative real-time PCR. A significant response was observed for AcobZIP24 against all kinds of abiotic stresses at 24 and 48 h in pineapple root tissues. Our study provides a perspective for the evolutionary history and general biological involvement of the bZIP gene family of pineapple, which laid the foundation for future functional characterization of the bZIP genes in pineapple. [ABSTRACT FROM AUTHOR]

Summary In most sexually reproducing plants, a single somatic, sub-epidermal cell in an ovule is selected to differentiate into a megaspore mother cell, which is committed to giving rise to the female germline. However, it remains unclear how intercellular signaling among somatic cells results in only one cell in the sub-epidermal layer differentiating into the megaspore mother cell. Here we uncovered a role of the THO complex in restricting the megaspore mother cell fate to a single cell. Mutations in TEX1 , HPR1 , and THO6 , components of the THO/TREX complex, led to the formation of multiple megaspore mother cells, which were able to initiate gametogenesis. We demonstrated that TEX1 repressed the megaspore mother cell fate by promoting the biogenesis of TAS3 -derived trans -acting small interfering RNA (ta-siRNA), which represses ARF3 expression. The TEX1 protein was present in epidermal cells, but not in the germline, and, through TAS3 -derived ta-siRNA, restricted ARF3 expression to the medio domain of ovule primordia. Expansion of ARF3 expression into lateral epidermal cells in a TAS3 ta-siRNA-insensitive mutant led to the formation of supernumerary megaspore mother cells, suggesting that TEX1- and TAS3- mediated restriction of ARF3 expression limits excessive megaspore mother cell formation non-cell-autonomously. Our findings reveal the role of a small-RNA pathway in the regulation of female germline specification in Arabidopsis . [ABSTRACT FROM AUTHOR]

Background: Sugarcane ( Saccharum spontaneum L.), the major sugar and biofuel feedstock crop, is cultivated mainly by vegetative propagation worldwide due to the infertility of female reproductive organs resulting in the reduction of quality and output of sugar. Deciphering the gene expression profile during ovule development will improve our understanding of the complications underlying sexual reproduction in sugarcane. Optimal reference genes are essential for elucidating the expression pattern of a given gene by quantitative real-time PCR (qRT-PCR)., Method: In this study, based on transcriptome data obtained from sugarcane ovule, eighteen candidate reference genes were identified, cloned, and their expression levels were evaluated across five developmental stages ovule (AC, MMC, Meiosis, Mitosis, and Mature)., Results: Our results indicated that FAB2 and MOR1 were the most stably expressed genes during sugarcane female gametophyte development. Moreover, two genes, cell cycle-related genes REC8 and CDK , were selected, and their feasibility was validated. This study provides important insights into the female gametophyte development of sugarcane and reports novel reference genes for gene expression research on sugarcane sexual reproduction., Competing Interests: The authors declare that they have no competing interests., (© 2021 Yan et al.)