Time-Course Transcriptomic Profiling of Floral Induction in Cultivated Strawberry

Molecular mechanisms of flowering time differentiation revealed by transcriptomic sequencing and de novo analysis in Chinese invasive populations of Ambrosia artemisiifolia

BACKGROUND

Ambrosia artemisiifolia is a highly invasive herb with deleterious effects on public health and agricultural systems. Flowering time in this species has been reported to vary along a latitudinal gradient, which may contribute to local adaptation and invasion success in China. However, the molecular basis for the flowering time differentiation remains unclear.

RESULTS

A common garden experiment confirmed a latitudinal gradient in flowering time among seven Chinese populations. Differentially expressed genes (DEGs) across sampling times and flowering time groups were identified through transcriptome sequencing and analyses of DGE and WGCNA, and were partially annotated to circadian rhythm, light response and hormone response through GO enrichment. By annotating to Flowering Interactive Database (FLOR-ID) and protein-protein interaction (PPI) databases, 53 candidate genes for flowering time differentiation were identified, with 23 of these genes linked to the photoperiod pathway. Additionally, 43 of 53 candidate genes exhibited expression correlated with latitude. Six genes, including FKF1, FT, FUL, MAF2, WNK4 and WNK5, were inferred to promote flowering, while 5 genes, FBH3, FLK, NCL(1), POL2A, and ZHD4, likely repress flowering, based on their expression patterns in relation to latitude and sampling times. Notably, NCL(1), FBH3, MAF2, and FLK may function differently in A. artemisiifolia compared to Arabidopsis thaliana.

CONCLUSIONS

This study identified key candidate genes related to the differentiation of flowering time in Chinese ragweed populations, providing valuable insights into molecular mechanisms of phenological adaptation and invasive success of ragweed.

The NAC transcription factors play core roles in flowering and ripening fundamental to fruit yield and quality

Fruits are derived from flowers and play an important role in human food, nutrition, and health. In general, flowers determine the crop yield, and ripening affects the fruit quality. Although transcription factors (TFs) only account for a small part of plant transcriptomes, they control the global gene expression and regulation. The plant-specific NAC (NAM, ATAF, and CUC) TFs constitute a large family evolving concurrently with the transition of both aquatic-to-terrestrial plants and vegetative-to-reproductive growth. Thus, NACs play an important role in fruit yield and quality by determining shoot apical meristem (SAM) inflorescence and controlling ripening. The present review focuses on the various properties of NACs together with their function and regulation in flower formation and fruit ripening. Hitherto, we have a better understanding of the molecular mechanisms of NACs in ripening through abscisic acid (ABA) and ethylene (ETH), but how NACs regulate the expression of the inflorescence formation-related genes is largely unknown. In the future, we should focus on the analysis of NAC redundancy and identify the pivotal regulators of flowering and ripening. NACs are potentially vital manipulation targets for improving fruit quantity and quality.