Integrated Analyses of Transcriptome and Chlorophyll Fluorescence Characteristics Reveal the Mechanism Underlying Saline–Alkali Stress Tolerance in Kosteletzkya pentacarpos

Abstract

In recent years, soil salinization has become increasingly severe, and the ecological functions of saline–alkali soils have deteriorated because of the lack of plants. Therefore, understanding the tolerance mechanisms of saline–alkali-tolerant plants has become crucial to restore the ecological functions of saline–alkali soils. In this study, we evaluated the molecular mechanism underlying the tolerance of Kosteletzkya pentacarpos L. (seashore mallow) seedlings treated with 0.05 or 0.5% saline–alkali solution (NaCl: NaHCO3 = 4:1 mass ratio) for 1 and 7 days. We identified the key genes involved in tolerance to saline–alkali stress using orthogonal partial least squares regression analysis (OPLS-RA) based on both chlorophyll fluorescence indexes and stress-responsive genes using transcriptome analysis, and, finally, validated their expression using qRT-PCR. We observed minor changes in the maximum photochemical efficiency of the stressed seedlings, whose photosynthetic performance remained stable. Moreover, compared to the control, other indicators varied more evidently on day 7 of 0.5% saline–alkali treatment, but no variations were observed in other treatments. Transcriptome analysis revealed a total of 54,601 full-length sequences, with predominantly downregulated differentially expressed gene (DEG) expression. In the high concentration treatment, the expression of 89.11 and 88.38% of DEGs was downregulated on days 1 and 7, respectively. Furthermore, nine key genes, including KpAGO4, KpLARP1C, and KpPUB33, were involved in negative regulatory pathways, such as siRNA-mediated DNA methylation, inhibition of 5′-terminal oligopyrimidine mRNA translation, ubiquitin/proteasome degradation, and other pathways, including programmed cell death. Finally, quantitative analysis suggested that the expression of key genes was essentially downregulated. Thus, these genes can be used in plant molecular breeding in the future to generate efficient saline–alkali–tolerant plant germplasm resources to improve the ecological functions of saline–alkali landscapes.

Responses of growth and photosynthesis to alkaline stress in three willow species

“…S. matsudana φPo, Ψo, φEo and φDo had the same trend of change as those of the other two willows, but the magnitude of change was smaller, and φPo differed from the control only at pH 9.5. The three willow cuttings adjusted the energy allocation ratios of their own PS II reaction centres under alkaline stress, i.e., the quantum ratio of energy absorbed by antenna pigment cells for heat dissipation increased and the energy share of photochemical reactions decreased 41 . Plants rely on light energy through photosynthesis to synthesise organic matter.…”

Transcriptome and Metabolome Integrated Analysis Reveals the Mechanism of Cinnamomum bodinieri Root Response to Alkali Stress

“…). The combined effects of ion toxicity, osmotic stress and high pH stress, make the alkaline saline soil more detrimental to plants (Aurelio et al 2013;Zhou et al 2022). There exist the knowledge gap in the current understanding on the alkali tolerance mechanism of plants,therefore the current study aim to bridge the gap by analyzing the pathways and regulatory networks of Cinnamomum bodinieri in response to alkali stress.…”

Transcriptome and Metabolome Integrated Analysis Reveals the mechanism of Cinnamomum bodinieri root response to alkali stress

“…). The combined effects of ion toxicity, osmotic stress and high pH stress, make the alkaline saline soil more detrimental to plants (Aurelio et al 2013;Zhou et al 2022). There exist the knowledge gap in the current understanding on the alkali tolerance mechanism of plants,therefore the current study aim to bridge the gap by analyzing the pathways and regulatory networks of Cinnamomum bodinieri in response to alkali stress.…”