Differential photosynthetic responses to drought stress in peanut varieties: insights from transcriptome profiling and JIP-Test analysis

Abstract

Background: Drought stress poses a critical constraint to plant growth by impairing photosynthetic efficiency in crops.

Results: Through transcriptome profiling of two peanut cultivars with contrasting drought tolerance, Fuhua18 (drought-sensitive, FH18) and Nonghua5 (drought-tolerant, NH5), we identified significant enrichment of differentially expressed genes in photosynthesis-related pathways. Notably, these genes were predominantly downregulated in FH18. Subsequent physiological analysis revealed cultivar-specific responses: Chlorophyll content decreased in FH18 but increased in NH5 after 24 h of drought treatment, accompanied by significant reductions in net photosynthetic rate (Pn) and water use efficiency (WUE) in both cultivars. The drought-induced physiological perturbations were further evidenced by elevated electrolyte leakage and activated antioxidant systems. To dissect photosynthetic apparatus dynamics, we implemented JIP-test analysis of chlorophyll fluorescence kinetics. Both cultivars exhibited substantial increases in Vj and Vi parameters at 24 h, while FH18 demonstrated a pronounced elevation in Vk during the O-J phase transition, suggesting severe impairment of the oxygen-evolving complex. Quantitative evaluation of photosynthetic performance indices revealed marked declines in PI_abs and PI_total, indicating systemic damage to both PSI and PSII under drought stress. Comparative analysis identified 11 traits showing significant inter-cultivar variation, particularly in PSII reaction center parameters including PI_abs, DI₀/RC, RE₀/RC, ABS/RC, and TR₀/RC.

Conclusion: These findings provide mechanistic insights into cultivar-dependent photosynthetic responses to drought stress, offering potential biomarkers for breeding drought-resilient peanut varieties.

Keywords: Drought stress; JIP-test; PSII performance; Peanut; Photosynthesis.

Fig. 1

Schematic representation of photosynthetic electron transport chain and associated light reactions​​. This diagram illustrates key components of the light-dependent reactions in chloroplasts and expression patterns of related genes. The OEC at PSII catalyzes water splitting while PQ shuttles electrons through the Cyt b6f complex to PC. LHC transfer excitation energy to reaction centers. F-type ATP synthase facilitates proton gradient-driven ATP synthesis. Color-coded expression patterns in the lower panel indicate: red​​: upregulated, blue: downregulated

Fig. 2

The effect of drought stress on net photosynthetic rate (Pn, A) and water use efficiency (WUE, B) of drought tolerant variety (NH5) and drought sensitive variety (FH18). Different lowercase letters indicate significant differences among different treatments (P < 0.05). * and ** significant difference at the 0.05 and 0.01 probability level; NS no significant difference

Fig. 3

The effect of drought stress on membrane damage and antioxidant capacity of drought tolerant variety (NH5) and drought sensitive variety (FH18). A relative electrolyte leakage rate, (B) superoxide dismutase activity, (C) peroxidase activity, (D) catalase activity. Different lowercase letters indicate significant differences among different treatments (P <0.05). *and ** significant difference at the 0.05 and 0.01 probability level; NS no significant difference

Fig. 4

Chl a fluorescence rises OJIP curves of drought tolerant variety (NH5) and drought sensitive variety (FH18) under drought stress. Different lowercase letters indicate significant differences among different treatments (P < 0.05)

Fig. 5

Effect of drought stress on the K-step of the OJIP curves of drought tolerant variety (NH5) and drought sensitive variety (FH18). The W_OJ=(F_t–F_O)/(F_J–F_O), and △W_OJ=W_{OJ(treatment)}- W_OJ(control). Different lowercase letters indicate significant differences among different treatments (P < 0.05)

Fig. 6

Effect of the fluorescence O–I phase in drought tolerant variety (NH5) and drought sensitive variety (FH18) under drought stress. W_OI=(F_t-F_o)/(F_I-F_o), ΔW_OI=W_{OI(treatment)}-W_OJ(control)

Fig. 7

Relative changes of OJIP test parameter and pipeline models of phenomenological energy fluxes per excited cross section of drought tolerant variety (NH5) and drought sensitive variety (FH18) under drought stress. A and C: NH5, B and D: FH18, and different lowercase letters in pipeline models indicate significant differences among different treatments (P < 0.05)

Fig. 8

Effects of drought stress on the JIP-test parameters of drought tolerant variety (NH5) and drought sensitive variety (FH18). Different lowercase letters indicate significant differences among different treatments (P < 0.05). * and ** significant difference at the 0.05 and 0.01 probability level; NS no significant difference

Fig. 9

Variability and correlation analysis of peanut with different drought tolerance. A The variability of peanut, △V=|variability_NH5- variability_FH18|. B The correlation analysis of peanut, p-value < 0.001 ***, p-value < 0.01 **, p-value < 0.05 *, p-value < 0.10