SiO2-NPs和PGPR对低温胁迫下金鱼草生长生理的影响

Effects of SiO2-NPs and PGPR on growth physiology of Antirrhinum majus under low-temperature stress

关键词:  二氧化硅纳米粒子(SiO₂-NPs), 植物根际促生菌, 低温, 金鱼草, 叶解剖特征, 叶绿素荧光参数, 光合酶活性

Key words:  SiO₂ nanoporticles(SiO₂-NPs), plant growth promoting rhizobacteria(PGPR), low-temperature, Antirrhinum majus, leaf anatomical characteristics, chlorophyll fluorescence parameters, photosynthetic enzyme activity

摘要:

为探究二氧化硅纳米粒子(SiO₂-NPs,20 nm粒径)和植物根际促生菌(PGPR)对低温胁迫下金鱼草(Antirrhinum majus)生长生理的调控作用,以常温(昼25 ℃/夜18 ℃)为对照(CK),测定低温胁迫(昼 7 ℃/夜 4 ℃,LT)下叶面喷施浓度S₁(50 mg·L^-1)、S₂(100 mg·L^-1)、S₃(200 mg·L^-1)的SiO₂-NPs,以及与PGPR菌株短小芽孢杆菌(Bacillus pumilus)复合处理下的金鱼草生物量、叶解剖结构、叶绿素含量及荧光参数、光合生理等指标。结果表明:(1)低温胁迫显著降低金鱼草株高、茎粗、生物量及叶片栅栏组织、海绵组织的厚度与组织结构紧密度,叶片喷施不同浓度SiO₂-NPs或复合PGPR处理可缓解其生长抑制,提高组织结构紧密度。(2)与单独低温胁迫处理(LT)相比,LT+S₂+PGPR处理能促进金鱼草光合作用,金鱼草叶片叶绿素a、叶绿素b、总叶绿素及类胡萝卜素的含量较LT处理分别增加25.6%、38.5%、29.3%和29.6%,叶绿素荧光参数中PS Ⅱ最大光化学效率(F_v/F_m)、PS Ⅱ实际光化学效率(φPS Ⅱ)和光化学猝灭系数(qP)分别增加24.9%、65.0%和37.8%,而非光化学猝灭系数(NPQ)则下降。(3)低温胁迫抑制了金鱼草净光合速率(P_n)、蒸腾速率(T_r)和气孔导度(G_s),LT+S₂+PGPR处理对P_n、T_r和G_s的提升效果最显著,较LT处理分别提高137.1%、109.9%和156.9%。(4)叶片喷施不同浓度SiO₂-NPs或复合PGPR处理能够显著提高金鱼草叶中磷酸烯醇丙酮酸羧化酶(PEPC)活性和核酮糖-1,5-二磷酸羧化酶(Rubisco)活性,降低叶中脱落酸(ABA)含量并增强叶水势(LWP)来缓解金鱼草受到的低温伤害。综上认为,LT+S₂+PGPR处理效果最优,二者表现出协同增效作用,可显著增强金鱼草低温耐受性,为其早春抗寒栽培提供技术支撑。

Abstract:

To investigate the regulatory effects of SiO₂ nanoparticles(SiO₂-NPs, 20 nm particle size)and plant growth promoting rhizobacteria(PGPR)on the growth and physiology of Antirrhinum majus under low-temperature stress, this study used normal temperature( 25 ℃ day/18 ℃ night )as the control(CK). The biomass, leaf anatomical structure, chlorophyll content, chlorophyll fluorescence parameters, and photosynthetic physiological indices of A. majus were determined under low-temperature stress(7 ℃ day / 4 ℃ night, LT)after foliar spraying of SiO₂-NPs at three concentrations [S₁(50 mg·L^-1), S₂(100 mg·L^-1), S₃(200 mg·L^-1)] alone or in combined treatment with PGPR strain Bacillus pumilus. The results were as follows:(1)Low-temperature stress significantly reduced the plant height, stem diameter, biomass, palisade tissue thickness, spongy tissue thickness, and tissue structure tightness in A. majus leaves. Spraying different concentrations of SiO₂-NPs or combined PGPR treatment on leaves could alleviate the growth inhibition and improve the tissue structure tightness.(2)Compared with the single low-temperature stress treatment(LT), contents of chlorophyll a, chlorophyll b, total chlorophyll, and carotenoids in A. majus treated with LT+S₂+PGPR increased by 25.6%, 38.5%, 29.3%, and 29.6%, respectively. The maximum photochemical efficiency of PS Ⅱ(F_v/F_m), actual photochemical efficiency of PS Ⅱ(φPS Ⅱ), and photochemical quenching coefficient(qP)in chlorophyll fluorescence parameters increased by 24.9%, 65.0%, and 37.8%, respectively, while the non-photochemical quenching coefficient(NPQ)decreased.(3)Low-temperature stress inhibited the increase of net photosynthetic rate(P_n), transpiration rate(T_r), and stomatal conductance(G_s)of A. majus. The LT+S₂+PGPR treatment had the most significant promoting effect on P_n, T_r, and G_s, which were 137.1%, 109.9%, and 156.9% higher than those under the LT treatment, respectively.(4)Spraying different concentrations of SiO₂-NPs or combined PGPR treatment on leaves could significantly increase the activities of phosphoenolpyruvate carboxylase(PEPC)and ribulose-1,5-diphosphate carboxylase(Rubisco)in A. majus leaves, reduce the content of abscisic acid(ABA)in leaves, and enhance leaf water potential(LWP)to alleviate the low-temperature stress experienced by A. majus. In summary, LT+S₂+PGPR treatment demonstrated optimal efficacy, exhibiting a synergistic effect that significantly enhanced the low-temperature tolerance of A. majus. This provides technical support for its early spring cold-resistant cultivation.