Comparative transcriptomic analysis of transcription factors and hormones during flower bud differentiation in 'Red Globe' grape under red‒blue light

Shading Treatment Reduces Grape Sugar Content by Suppressing Photosynthesis-Antenna Protein Pathway Gene Expression in Grape Berries

To explore the impact of shade treatment on grape berries, 'Marselan' grape berries were bagged under different light transmission rates (100% (CK), 75% (A), 50% (B), 25% (C), 0% (D)). It was observed that this treatment delayed the ripening of the grape berries. The individual weight of the grape berries, as well as the content of fructose, glucose, soluble sugars, and organic acids in the berries, was measured at 90, 100, and 125 days after flowering (DAF90, DAF100, DAF125). The results revealed that shading treatment reduced the sugar content in grape berries; the levels of fructose and glucose were higher in the CK treatment compared to the other treatments, and they increased with the duration of the shading treatment. Conversely, the sucrose content exhibited the opposite trend. Additionally, as the weight of the grape berries increased, the content of soluble solids and soluble sugars in the berries also increased, while the titratable acidity decreased. Furthermore, 16 differentially expressed genes (DEGs) were identified in the photosynthesis-antenna protein pathway from the transcriptome sequencing data. Correlation analysis revealed that the expression levels of genes VIT_08s0007g02190 (Lhcb4) and VIT_15s0024g00040 (Lhca3) were positively correlated with sugar content in the berries at DAF100, but negatively correlated at DAF125. qRT-PCR results confirmed the correlation analysis. This indicates that shading grape clusters inhibits the expression of genes in the photosynthesis-antenna protein pathway in the grape berries, leading to a decrease in sugar content. This finding contributes to a deeper understanding of the impact mechanisms of grape cluster shading on berry quality, providing important scientific grounds for improving grape berry quality.

Integrative Metabolomic and Transcriptomic Analysis Elucidates That the Mechanism of Phytohormones Regulates Floral Bud Development in Alfalfa

Floral bud growth influences seed yield and quality; however, the molecular mechanism underlying the development of floral buds in alfalfa (Medicago sativa) is still unclear. Here, we comprehensively analyzed the transcriptome and targeted metabolome across the early, mid, and late bud developmental stages (D1, D2, and D3) in alfalfa. The metabolomic results revealed that gibberellin (GA), auxin (IAA), cytokinin (CK), and jasmonic acid (JA) might play an essential role in the developmental stages of floral bud in alfalfa. Moreover, we identified some key genes associated with GA, IAA, CK, and JA biosynthesis, including CPS, KS, GA20ox, GA3ox, GA2ox, YUCCA6, amid, ALDH, IPT, CYP735A, LOX, AOC, OPR, MFP2, and JMT. Additionally, many candidate genes were detected in the GA, IAA, CK, and JA signaling pathways, including GID1, DELLA, TF, AUX1, AUX/IAA, ARF, GH3, SAUR, AHP, B-ARR, A-ARR, JAR1, JAZ, and MYC2. Furthermore, some TFs related to flower growth were screened in three groups, such as AP2/ERF-ERF, MYB, MADS-M-type, bHLH, NAC, WRKY, HSF, and LFY. The findings of this study revealed the potential mechanism of floral bud differentiation and development in alfalfa and established a theoretical foundation for improving the seed yield of alfalfa.

Rapid diversification of grey mangroves (Avicennia marina) driven by geographic isolation and extreme environmental conditions in the Arabian Peninsula

Biological systems occurring in ecologically heterogeneous and spatially discontinuous habitats provide an ideal opportunity to investigate the relative roles of neutral and selective factors in driving lineage diversification. The grey mangroves (Avicennia marina) of Arabia occur at the northern edge of the species' range and are subject to variable, often extreme, environmental conditions, as well as historic large fluctuations in habitat availability and connectivity resulting from Quaternary glacial cycles. Here, we analyse fully sequenced genomes sampled from 19 locations across the Red Sea, the Arabian Sea and the Persian/Arabian Gulf (PAG) to reconstruct the evolutionary history of the species in the region and to identify adaptive mechanisms of lineage diversification. Population structure and phylogenetic analyses revealed marked genetic structure correlating with geographic distance and highly supported clades among and within the seas surrounding the Arabian Peninsula. Demographic modelling showed times of divergence consistent with recent periods of geographic isolation and low marine connectivity during glaciations, suggesting the presence of (cryptic) glacial refugia in the Red Sea and the PAG. Significant migration was detected within the Red Sea and the PAG, and across the Strait of Hormuz to the Arabian Sea, suggesting gene flow upon secondary contact among populations. Genetic-environment association analyses revealed high levels of adaptive divergence and detected signs of multi-loci local adaptation driven by temperature extremes and hypersalinity. These results support a process of rapid diversification resulting from the combined effects of historical factors and ecological selection and reveal mangrove peripheral environments as relevant drivers of lineage diversity.