Abstract
Abstract
Background
Cotton ovule development is a critical determinant of fiber yield and seed quality, yet it is highly vulnerable to drought stress. While phytohormonal and transcriptional regulations during ovule development have been extensively studied, the precise developmental window during which drought triggers abortion remains unclear. Furthermore, both the metabolic perturbations within this window and their molecular coordination in developing ovules remain largely unexplored.
Results
In this study, comprehensive phenotypic observations were performed on cotton ovules at five developmental stages (0, 5, 10, 15, and 20 days post anthesis, DPA) under both well‑watered and drought conditions. Drought stress increased the ovule abortion rate from 37.5% to approximately 60%. Paraffin sections of ovules revealed morphological signs of abortion as early as 10 DPA. Transcriptomic analysis showed that the number of differentially expressed genes (DEGs) increased dramatically at 5 DPA, suggesting this stage as a critical responsive window. Temporal clustering analysis further indicated that abortion occurred during the phase of massive storage reserve accumulation (5–10 DPA). Subsequently, a broad‑spectrum targeted metabolomic analysis was conducted at 5 DPA, identifying 528 differentially accumulated metabolites, among which ABC transporters emerged as a prominent core hub linking amino acid and secondary metabolite pathways. Integrated multi‑omics data revealed that, although most amino acid and sucrose transporter genes were upregulated under drought stress, the actual contents of soluble sugars and proteins declined significantly, uncovering a critical imbalance between enhanced transport demand and insufficient nutrient supply.
Conclusions
Collectively, these results pinpoint 5 DPA as the decisive window for drought‑induced ovule abortion and demonstrate that disruption of carbon‑nitrogen assimilate allocation—particularly through ABC transporter‑mediated processes—acts as a metabolic trigger for abortion. This study provides new mechanistic insights into drought‑induced reproductive failure in cotton and offers candidate targets for drought‑resistant breeding and production management.