Production of endo-β-mannanase, superoxide radicals, hydrogen peroxide, and peroxidase in the micropylar endosperm of pepper seed during germination is determined by the endosperm itself
2022
Shi, Zhaowan | Li, Zhaoyang | Yang, Xueqin | He, Yanyan | Wang, Xiaofeng
Cell wall-loosening enzymes and non-enzymatic factors have been demonstrated to be expressed specifically in the micropylar endosperm during seed germination, but the reason remains poorly understood. In this study, we used pepper seeds as plant materials to investigate this. At first, we showed that endo-β-mannanase, O₂.⁻, H₂O₂, and ∙OH production-related peroxidase were tissue-specifically expressed also in the micropylar endosperm prior to radicle protrusion and thus played important roles in seed germination. Next, we incubated isolated de-embryonated seed halves with endosperm and seed coat but without embryo (shorted as endosperm-halves) alone in the water and found that they could still produce endo-β-mannanase, O₂∙־, H₂O₂, and peroxidase specifically in the micropylar endosperm. We also utilized small glass beads to mimic radicles to touch onto the lateral areas of the incubated isolated endosperm-halves but found no endo-β-mannanase, O₂∙־, H₂O₂, and peroxidase were induced specifically in the touched areas. Therefore, we propose that tissue-specific production of endo-β-mannanase, O₂∙־, H₂O₂, and peroxidase in the micropylar endosperm is determined by the endosperm itself.
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