Whole-genome duplication events often confer autopolyploid plants with bigger leaf blades compared with those of their diploid counterparts. However, little is known regarding the potential molecular basis of bigger leaf formation in autopolyploid plants. Here, we focused on the oilseed crop castor bean (Ricinus communis L.) to investigate the molecular basis underlying leaf size variation using a synthetic autotetraploid by doubling the diploid homologous chromosomes. The results showed that the leaf area of autotetraploids was significantly larger than that of diploids. According to our histological observations, the formation of larger leaf blades in tetraploid castor beans is attributed to both an increase in cell size and an increase in cell number. A total of 3,464 differentially expressed genes (DEGs) between diploids and tetraploids were identified by RNA sequencing analysis. The expression of key genes related to cell wall loosening, cell expansion and cell division was higher in tetraploid leaf blades compared to diploids, resulting in enlarged tetraploid leaf blades, such as SUS2, SUS4, XYL1, Xyl2, XTH30, XTH32, EXPA1, EXPA4, EXPA6, EXPB3, CYCD3;1 and CYCD3;3 were significantly up-regulated in tetraploids. Concurrently, auxin-responsive genes (SAUR20, SAUR23, and SAUR51) in the auxin signaling pathway showed significant up-regulated in tetraploids, facilitating leaf cell expansion. Transcription factors (TFs) including HAT22, SRM1, ERF4, and DOF3.4 likely regulate cell expansion and elongation pathways, ultimately driving the enlargement of tetraploid leaf blades. Our findings provide important insight into understanding the potential molecular basis of gene dosage effects on trait variation in autopolyploid plants.

Castor bean (Ricinus communis, 2 n = 2x=20) ranks as a highly significant non-edible oil crop globally, drawing substantial attention from breeders due to the extensive industrial applications of its seed oil. Artificial induction of polyploidy is an effective strategy to improve crop yield, but it has been less applied in castor bean and underlying mechanisms remain unclear. Here, we developed a tetraploid castor bean by colchicine induction with the enhancement of seed traits, including seed size, weight and oil content. Histological analysis showed that the increased seed size in tetraploid castor may cause by the increased cell size. Combined with transcriptome analysis, we identified many key genes involving into the hormonal signaling network, especially brassinosteroid and cytokinin, which may have the potential function in regulating seed size and weight in tetraploid castor. Meanwhile, we noted that many genes encoding key enzymes participating in glycolysis, fatty acids synthesis and triacylglycerol assembly were significantly up-regulated in tetraploid castor seeds as compared with diploid ones. Importantly, DAP-seq (DNA affinity purification sequencing) analysis showed that transcription factor WRINKLED1 might serve as a crucial regulator driving seed oil synthesis in tetraploid castor beans. Tetraploid castor bean lines we created provide new resources for castor bean breeding system. And importantly, these findings enhance our comprehension of the molecular mechanisms underlying seed yield traits, thereby aiding the genetic enhancement of desirable seed traits in castor beans.

Mouse zygotes undergo multiple rounds of cell division, resulting in the formation of preimplantation blastocysts comprising three lineages: trophectoderm (TE), epiblast (EPI), and primitive endoderm (PrE). Cell fate determination plays a crucial role in establishing a healthy pregnancy. The initial separation of lineages gives rise to TE and inner cell mass (ICM), from which trophoblast stem cells (TSC) and embryonic stem cells (ESC) can be derived in vitro. Studying lineage differentiation is greatly facilitated by the clear functional distinction between TSC and ESC. However, transitioning between these two types of cells naturally poses challenges. In this study, we demonstrate that inhibiting LATS kinase promotes the conversion of ICM to TE and also effectively reprograms ESC into stable, self-renewing TS-like cells (TSLC). Compared to TSC, TSLC exhibits similar molecular properties, including the high expression of marker genes such as Cdx2, Eomes, and Tfap2c, as well as hypomethylation of their promoters. Importantly, TSLC not only displays the ability to differentiate into mature trophoblast cells in vitro but also participates in placenta formation in vivo. These findings highlight the efficient reprogramming of ESCs into TSLCs using a small molecular inducer, which provides a new reference for understanding the regulatory network between ESCs and TSCs.

The vasa mRNA encodes a putative RNA helicase that belongs to the DEAD-box protein family. Vasa protein is a conserved germ cell marker ranging from fruit fly to human. In this study, we cloned the full-length vasa cDNA from the ovary of newt Cynops cyanurus and examined its expression in embryos and adult tissues. The predictive C. cyanurus Vasa protein sequence shares eight conserved regions with Vasa proteins from other vertebrates. The C. cyanurus vasa mRNA expression is restricted to testis and ovary. During oogenesis, vasa mRNA shows highest expression in the early stages of oocytes. However, it rapidly down-regulates during embryogenesis. These findings suggest that Vasa may be involved in early germ cell specification/initiation in C. cyanurus.

The Dazl (deleted in azoospermia-like) gene encodes an RNA-binding protein containing an RNA recognition motif (RRM) and a DAZ motif. Dazl is essential for gametogenesis in vertebrates. In this study, we report the cloning of Dazl cDNA from Cynops cyanurus. Ccdazl mRNA showed a germline-specific expression pattern as expected. Ccdazl expression gradually decreased during oogenesis, suggesting that it may be involved in oocyte development. Phylogenetic analysis revealed that the Ccdazl protein shares conserved motifs/domains with Dazl proteins from other species. Cloning of Ccdazl provides a new tool to carry out comparative studies of germ cell development in amphibians.