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Parthenocarpy is an important way for seedless fruit production in citrus. However, the molecular mechanism(s) of parthenocarpy in pomelo is still unknown. Our initial study found significantly different parthenocarpic abilities in Guanximiyou (G) and Shatianyou (S) pomelo following emasculation, and an endogenous hormone content assay revealed that indole-3-acetic acid (IAA), gibberellic acid (GA3) and zeatin (ZT) jointly promoted fruit expansion and cell division in parthenocarpic pomelo (G pomelo). To unravel the underlying molecular mechanism(s), we conducted the first transcriptome analysis on the two pomelo accessions at these two critical stages: the fruit initiation stage and the rapid expansion stage, in order to identify genes associated with parthenocarpy. This analysis yielded approximately 7.86 Gb of high-quality reads, and the subsequent de novo assembly resulted in the identification of 5,792 DEGs (Differentially Expressed Genes). Among these, a range of transcription factor families such as CgERF, CgC2H2, CgbHLH, CgNAC and CgMYB, along with genes like CgLAX2, CgGH3.6 and CgGH3, emerged as potential candidates contributing to pomelo parthenocarpy, as confirmed by qRT-PCR analysis. The present study provides comprehensive transcriptomic profiles of both parthenocarpic and non-parthenocarpic pomelos, reveals several metabolic pathways linked to parthenocarpy, and highlights the significant role of plant hormones in its regulation. These findings deepen our understanding of the molecular mechanisms underlying parthenocarpy in pomelo.

Soybean quality and production are determined by seed viability. A seed’s capacity to sustain germination via dry storage is known as its seed life. Thus, one of the main objectives for breeders is to preserve genetic variety and gather germplasm resources. However, seed quality and germplasm preservation have become significant obstacles. In this study, four artificially simulated aging treatment groups were set for 0, 24, 72, and 120 hours. Following an aging stress treatment, the transcriptome and metabolome data were compared in two soybean lines with notable differences in seed vigor—R31 (aging sensitive) and R80 (aging tolerant). The results showed that 83 (38 upregulated and 45 downregulated), 30 (19 upregulated and 11 downregulated), 90 (52 upregulated and 38 downregulated), and 54 (25 upregulated and 29 downregulated) DEGs were differentially expressed, respectively. A total of 62 (29 upregulated and 33 downregulated), 94 (49 upregulated and 45 downregulated), 91 (53 upregulated and 38 downregulated), and 135 (111 upregulated and 24 downregulated) differential metabolites accumulated. Combining the results of transcriptome and metabolome investigations demonstrated that the difference between R31 and R80 responses to aging stress was caused by genes related to phenylpropanoid metabolism pathway, which is linked to the seed metabolite caffeic acid. According to this study’s preliminary findings, the aging-resistant line accumulated more caffeic acid than the aging-sensitive line, which improved its capacity to block lipoxygenase (LOX) activity. An enzyme activity inhibition test was used to demonstrate the effect of caffeic acid. After soaking seeds in 1 mM caffeic acid (a LOX inhibitor) for 6 hours and artificially aging them for 24 hours, the germination rates of the R31 and R80 seeds were enhanced. In conclusion, caffeic acid has been shown to partially mitigate the negative effects of soybean seed aging stress and to improve seed vitality. This finding should serve as a theoretical foundation for future research on the aging mechanism of soybean seeds.

Double-flower Eriobotrya japonica, of which one phenotype is homeotic transformation of sepals into petals, is a new germplasm for revealing the molecular mechanisms underlying the floral organ transformation. Herein, we analyzed the sequence, expression pattern and functional characterization of EjPI, which encoded a B-class floral homeotic protein referred to as PISTILLATA ortholog, from genetically cognate single-flower and double-flower E. japonica. Phylogenetic analysis suggested that the EjPI gene was assigned to the rosids PI/GLO lineage. Analysis of protein sequence alignments showed that EjPI has typical domains of M, I, K, and C, and includes a distinctive PI motif at the C-terminal region. Compared with asterids PI/GLO lineage, the K1 and K3 subdomains of EjPI both contain a single amino acid difference. Subcellular localization of EjPI was determined to be in the nucleus. Expression pattern analysis revealed that EjPI expressed not only in petals, filament, and anther in single-flower E. japonica, but also in petaloid sepals in double-flower E. japonica. Meanwhile, there were high correlation between EjPI transcript level and petaloid area within a sepal. Furthermore, 35S::EjPI transgenic wild-type Arabidopsis caused the homeotic transformation of the first whorl sepals into petaloid sepals. Ectopic expression of EjPI in transgenic pi-1 mutant Arabidopsis rescued normal petals and stamens. These results suggest expression pattern of EjPI is associated with the formation of petaloid sepal. Our study provides the potential application of EjPI for biotechnical engineering to create petaloid sepals or regulate floral organ identity in angiosperms.

Soybean is one of the most important economic crops for both China and the United States (US). The exchange of germplasm between these two countries has long been active. In order to investigate genetic relationships between Chinese and US soybean germplasm, 277 Chinese soybean accessions and 300 US soybean accessions from geographically diverse regions were analyzed using 5,361 SNP markers. The genetic diversity and the polymorphism information content (PIC) of the Chinese accessions was higher than that of the US accessions. Population structure analysis, principal component analysis, and cluster analysis all showed that the genetic basis of Chinese soybeans is distinct from that of the USA. The groupings observed in clustering analysis reflected the geographical origins of the accessions; this conclusion was validated with both genetic distance analysis and relative kinship analysis. FST-based and EigenGWAS statistical analysis revealed high genetic variation between the two subpopulations. Analysis of the 10 loci with the strongest selection signals showed that many loci were located in chromosome regions that have previously been identified as quantitative trait loci (QTL) associated with environmental-adaptation-related and yield-related traits. The pattern of diversity among the American and Chinese accessions should help breeders to select appropriate parental accessions to enhance the performance of future soybean cultivars.