Identification of an Embryonic Cell-Specific Region within the Pineapple SERK1 Promoter

Unveiling the molecular mechanism involving anthocyanins in pineapple peel discoloration during fruit maturation

Peel color is a key factor that affects the fruit's aesthetic and economic values. Limited knowledge is available on the regulation of pineapple peel discoloration. Here, we report that a decrease in anthocyanin biosynthesis, particularly cyanidin, is predominantly associated with the pineapple peel color change during maturation. The findings suggest that the changes in the expression of key structural genes (early and late biosynthetic genes) of the anthocyanin (cyanidin) biosynthesis pathway are responsible for peel discoloration. Based on a gene co-expression analysis and a transient expression, two transcription factors i.e., AcHOX21 and AcMYB12, were identified, whose' downregulation leads to reduced anthocyanin accumulation with fruit maturation. The endogenous levels of jasmonic acid, gibberellic acid, and auxins are also involved in anthocyanin-content-led peel discoloration. Overall, the discovery of genes regulating anthocyanin biosynthesis in pineapple peel provides a theoretical basis for improving the fruit's aesthetic value through genetic engineering.

Transcriptome Landscape Analyses of the Regulatory Network for Zygotic Embryo Development in Paeonia ostii

Paeonia ostii is a worldwide ornamental flower and an emerging oil crop. Zyotic embryogenesis is a critical process during seed development, and it can provide a basis for improving the efficiency of somatic embryogenesis (SE). In this study, transcriptome sequencing of embryo development was performed to investigate gene expression profiling in P. ostii and identified Differentially expressed genes (DEGs) related to transcription factors, plant hormones, and antioxidant enzymes. The results indicated that IAA (Indole-3-acetic acid), GA (Gibberellin), BR (Brassinosteroid) and ETH (Ethylene) were beneficial to early embryonic morphogenesis, while CTK (Cytokinin) and ABA (Abscisic Acid) promoted embryo morphogenesis and maturation. The antioxidant enzymes' activity was the highest in early embryos and an important participant in embryo formation. The high expression of the genes encoding fatty acid desaturase was beneficial to fast oil accumulation. Representative DEGs were selected and validated using qRT-PCR. Protein-protein interaction network (PPI) was predicted, and six central node proteins, including AUX1, PIN1, ARF6, LAX3, ABCB19, PIF3, and PIF4, were screened. Our results provided new insights into the formation of embryo development and even somatic embryo development in tree peonies.

Genome-Wide Identification and Expression Patterns of AcSWEET Family in Pineapple and AcSWEET11 Mediated Sugar Accumulation

Pineapple (Ananas comosus L.) is an important fruit crop in tropical regions, and it requires efficient sugar allocation during fruit development. Sugars Will Eventually be Exported Transporters (SWEETs) are a group of novel sugar transporters which play critical roles in seed and fruit development. However, the function of AcSWEETs remains unknown in the sugar accumulation. Herein, 17 AcSWEETs were isolated and unevenly located in 11 chromosomes. Analysis of a phylogenetic tree indicated that 17 genes were classified into four clades, and the majority of AcSWEETs in each clade shared similar conserved motifs and gene structures. Tissue-specific gene expression showed that expression profiles of AcSWEETs displayed differences in different tissues and five AcSWEETs were strongly expressed during fruit development. AcSWEET11 was highly expressed in the stage of mature fruits in 'Tainong16' and 'Comte de paris', which indicates that AcSWEET11 was important to fruit development. Subcellular localization analysis showed that AcSWEET11 was located in the cell membrane. Notably, overexpression of AcSWEET11 could improve sugar accumulation in pineapple callus and transgenic tomato, which suggests that AcSWEET11 might positively contribute to sugar accumulation in pineapple fruit development. These results may provide insights to enhance sugar accumulation in fruit, thus improving pineapple quality in the future.

Methylation Analysis of CpG Islands in Pineapple SERK1 Promoter

Somatic embryogenesis (SE) is a more rapid and controllable method for plant propagation than traditional breeding methods. However, it often suffers from limited efficiency. SERK1 promotes SE in several plants, including pineapple (Ananas comosus L.). We investigate the embryonic cell-specific transcriptional regulation of AcSERK1 by methylation analysis of CpG islands in AcSERK1 regulatory sequences. This revealed differences in the methylation status of CpG islands between embryonic callus and non-embryonic callus; the methylation inhibitor 5-azaC increased AcSERK1 expression and also accelerated SE. These findings indicate that the expression of AcSERK1 is regulated epigenetically. This study lays the foundation for further analysis of epigenetic regulatory mechanisms that may enhance the efficiency of SE in pineapple and other plants.