Physiological and transcriptomic analysis of the effects of different selenium and potassium application concentrations on the growth and development of banana seedlings

Abstract This study aims to investigate the effects of selenium on potassium absorption and accumulation, as well as the influence of varying concentrations of selenium-potassium combined applications on the growth of banana seedlings. A combined selenium-potassium application experiment was conducted on Guijiao No. 9 banana seedlings, using potassium chloride (KCl) as the potassium source and sodium selenate (Na₂SeO₄) as the selenium source. At 20 and 40 days post-treatment, measurements were taken for the fresh and dry weights, as well as the selenium and potassium contents in the roots, stems, and leaves. Additionally, leaf antioxidant enzyme activities, soluble protein content, and soluble sugar content were assessed. Under a constant KCl concentration, an increase in Na₂SeO₄ concentration initially led to an increase in fresh and dry weights of the roots, stems, and leaves, along with enhanced antioxidant enzyme activities, soluble protein, and soluble sugar contents at 20 days post-treatment, which subsequently decreased. The potassium contents in the roots and stems showed no significant variation at 20 days but displayed an initial increase followed by a decline at 40 days, while leaf potassium content remained largely unchanged. The selenium contents in all plant tissues exhibited an increasing trend. Transcriptome analysis identified 2,455, 3,530, 3,134, 2,541, 3,422, 1,101, 471, and 3,221 differentially expressed genes (DEGs) between the groups YT1/YCK1, YT2/YCK2, YCK1/YCK2, YT1/YT2, GT1/GCK1, GT2/GCK2, GCK1/GCK2, and GT1/GT2, respectively. A significant number of these DEGs were enriched in the plant hormone signal transduction pathway. Notably, 472 DEGs from the GT1/GT2 comparison may play a key role in promoting selenium and potassium absorption in banana seedlings. The combination of KCl at 400 mg·L⁻¹ and Na₂SeO₄ at 1.0 mg·L⁻¹ increased the biomass of roots, stems, and leaves, as well as in selenium and potassium contents, and enhanced antioxidant enzyme activities, which facilitated the growth of banana seedlings. Kyoto Encyclopedia of Genes and Genomes pathway analysis revealed that DEGs were significantly enriched in plant hormone signal transduction pathways. Significance: The findings provide theoretical support for further studies on the physiological and biochemical effects, as well as the yield and quality of field-cultivated banana.