The testa of Arabidopsis seeds plays a critical role in controlling dormancy, germination, and seed longevity. Mutants with altered testa pigmentation or structure exhibit reduced dormancy and increased permeability to tetrazolium salts, indicating that testa integrity is essential for dormancy maintenance. These defects are linked to impaired endothelium and parenchymatic layer pigmentation, as well as structural abnormalities. Testa mutants deteriorate more rapidly during storage than wild-type seeds, with structural mutants being most affected. The testa's role in dormancy is likely due to its permeability and thickness, which are influenced by chemical compounds and structural elements. The testa also contributes to seed coat impermeability to water and oxygen, which restricts germination. Seed coat pigmentation, particularly condensed tannins, is associated with increased resistance to solute leakage and imbibition damage, improving seed vigor and germination. The study highlights the importance of testa structure and pigmentation in determining seed dormancy, germination, and longevity in Arabidopsis. Mutants with altered testa characteristics show reduced dormancy and increased germination rates, suggesting that testa defects can significantly impact seed behavior. The findings underscore the complex interplay between testa structure, pigmentation, and seed physiology in Arabidopsis.The testa of Arabidopsis seeds plays a critical role in controlling dormancy, germination, and seed longevity. Mutants with altered testa pigmentation or structure exhibit reduced dormancy and increased permeability to tetrazolium salts, indicating that testa integrity is essential for dormancy maintenance. These defects are linked to impaired endothelium and parenchymatic layer pigmentation, as well as structural abnormalities. Testa mutants deteriorate more rapidly during storage than wild-type seeds, with structural mutants being most affected. The testa's role in dormancy is likely due to its permeability and thickness, which are influenced by chemical compounds and structural elements. The testa also contributes to seed coat impermeability to water and oxygen, which restricts germination. Seed coat pigmentation, particularly condensed tannins, is associated with increased resistance to solute leakage and imbibition damage, improving seed vigor and germination. The study highlights the importance of testa structure and pigmentation in determining seed dormancy, germination, and longevity in Arabidopsis. Mutants with altered testa characteristics show reduced dormancy and increased germination rates, suggesting that testa defects can significantly impact seed behavior. The findings underscore the complex interplay between testa structure, pigmentation, and seed physiology in Arabidopsis.