酸胁迫对海南绿橙生理代谢及抗氧化调控基因表达的影响OA

This study aimed to investigate the effects of acidic soil on the growth metabolism and photosynthesis of Hainan green sweet orange(Citrus sinensis L.)and to elucidate its antioxidant regulatory mechanisms under acid stress.A pot experiment was conducted to analyze the physiological metabolic changes,antioxidant responses,and expression patterns of key antioxidant enzyme regulatory genes in green sweet orange under acid stress.The results showed that the plant height growth,leaf area and fresh weight of green sweet orange plants decreased significantly under a strongly acidic soil environment,with the most serious effect of pH 3.5 treatment;the weakly acidic(pH 6.5)soil could promote the growth of plants,which manifested as positive growth in the amount of each growth index.Strong acid treatment significantly impaired photosynthesis and normal growth metabolism of green sweet or-ange leaves,manifested as negative growth in transpiration rate(Tr)and stomatal conductance(Gs)were significantly reduced.Superoxide dismutase(SOD)and phenylalanine ammonia-lyase(PAL)activities increased by 6.60-fold and 5.90-fold at 24 h post-treatment under pH 3.5.The malondialdehyde(MDA)content in leaves treated with pH 3.5 increased by 6.47-fold compared to the initial time point(0 h),significantly higher than that under pH 6.5.Princi-pal component analysis(PC A)and redundancy analysis(RDA)revealed a significant negative correlation between enzyme activity and physiological-biochemical indices(R2=0.82).Gene expression analysis demonstrated that Cs-SOD and CsPAL reached peak levels at 24,48 h post-stress respectively and remained upregulated within 72 h,showing 2.33-fold and 2.64-fold increases compared to 0 h,respectively.In summary,strongly acidic soil inhibits the growth and development of green sweet orange by reducing photosynthetic pigment content and metabolic effi-ciency.SOD and PAL serve as key antioxidant enzymes in response to acid stress,with CsSOD and CsPAL genes dy-namically regulating enzymatic activity to mitigate stress.