Strigolactone alleviates the salinity-alkalinity stress of Malus hupehensis seedlings

Abstract

Salinity-alkalinity stress can remarkably affect the growth and yield of apple. Strigolactone (SL) is a class of carotenoid-derived compounds that functions in stress tolerance. However, the effects and mechanism of exogenous SL on the salinity-alkalinity tolerance of apple seedlings remain unclear. Here, we assessed the effect of SL on the salinity-alkalinity stress response of Malus hupehensis seedlings. Results showed that treatment with 100 μM exogenous SL analog (GR24) could effectively alleviate salinity-alkalinity stress with higher chlorophyll content and photosynthetic rate than the apple seedlings without GR24 treatment. The mechanism was also explored: First, exogenous GR24 regulated the expression of Na+/K+ transporter genes and decreased the ratio of Na+/K+ in the cytoplasm to maintain ion homeostasis. Second, exogenous GR24 increased the enzyme activities of superoxide, peroxidase and catalase, thereby eliminating reactive oxygen species production. Third, exogenous GR24 alleviated the high pH stress by regulating the expression of H+-ATPase genes and inducing the production of organic acid. Last, exogenous GR24 application increased endogenous acetic acid, abscisic acid, zeatin riboside, and GA3 contents for co-responding to salinity-alkalinity stress indirectly. This study will provide important theoretical basis for analyzing the mechanism of exogenous GR24 in improving salinity-alkalinity tolerance of apple.

Strigolactone Mediates Moso Bamboo Root Response to Phosphate Stress

“…Our results showed that GR24 upregulated the expression of all Pi-starvation-responsive genes ( SPXs ), indicating that SL regulates SPXs (Figure S12A–C). As mentioned previously, GR24 remarkably induced the expression levels of SL-biosynthesis and -signal transduction genes inMalus hupehensis under abiotic stress, and GR24 decreased D10 transcript levels in d10-1 and wild-type rice seedlings . We also found that the expression of SL-biosynthesis genes ( CCD7 , D27 , MAX1 , and D10 ) and SL-signaling gene D3 were upregulated by GR24 under low Pi between 48 and 192 h but dropped to the control level at 336 h (Figure S12), further supporting the idea that endogenous strigolactone levels were under homeostasis control.…”

An assessment of the physicochemical characteristics and essential oil composition of Mentha longifolia (L.) Huds. exposed to different salt stress conditions

“…Further, high KCl also causes the physiological drought condition in plants, causing osmotic stress, which leads to decreases in chlorophyll content and RWC and increases in EL, proline content, and DPPH activity in M. longifolia . According to previous research, the chlorophyll content decreases with KCl treatment in Malus hupehensis and is recovered by the application of exogenous strigolactones ( Ma et al., 2022 ), whereas the proline content increases with 50 mM and 75 mM KCl treatment in pomegranate varieties ( Dichala et al., 2022 ).…”

Strigolactones as a hormonal hub for the acclimation and priming to environmental stress in plants

“…The effects of GR24 treatments on responses to high salinity were tested in several species: arabidopsis (Ha et al, 2014); beet ( Brassica napus L.) (N. Ma et al, 2017); rice (Ling et al, 2020); cucumber ( Cucumis sativus L.) (X.‐H. Zhang et al, 2022); tomato (H. Liu, Li, et al, 2022); wheat ( Triticum aestivum L.) (Kausar & Shahbaz, 2017); sunflower ( Helianthus annuus L.) (Sarwar & Shahbaz, 2019, 2020; Zulfiqar et al, 2021); wild sage ( Salvia nemorosa L.) (Sharifi & Bidabadi, 2020); corn ( Zea mays ) (Iftikhar et al, 2022); and apple tree ( Malus hupehensis Rehd) (C. Ma et al, 2022; Zheng et al, 2021). A realignment of physiological and molecular indicators to unstressed controls was consistently observed following treatment, namely in terms of protection from a drop in germination efficiency, biomass and/or chlorophyll content loss; maintenance of gas exchange parameters (net photosynthetic rate, stomatal conductance, transpiration); and lower malondialdehyde content (MDA, a biomarker of polyunsaturated lipid peroxidation that accumulates in stressed cells).…”

“…The effects of GR24 treatments on responses to high salinity were tested in several species: arabidopsis (Ha et al, 2014); beet (Brassica napus L.) (N. Ma et al, 2017); rice (Ling et al, 2020); cucumber (Cucumis sativus L.) (X.-H. Zhang et al, 2022); tomato (H. Liu, Li, et al, 2022); wheat (Triticum aestivum L.) (Kausar & Shahbaz, 2017); sunflower (Helianthus annuus L.) (Sarwar & Shahbaz, 2019Zulfiqar et al, 2021); wild sage (Salvia nemorosa L.) (Sharifi & Bidabadi, 2020); corn (Zea mays) (Iftikhar et al, 2022); and apple tree (Malus hupehensis Rehd) (C. Ma et al, 2022;Zheng et al, 2021) A mixed stress-coping strategy (avoidance and tolerance) seems induced by GR24 (e.g., by increasing root/shoot biomass ratios or reducing the uptake of soil pollutants).…”