Selênio na micropropagação de cultivares de batata-doce

Abstract

Sweet potato (Ipomoea batatas L.) is a crop of major socioeconomic importance, commonly propagated vegetatively. Micropropagation enables the production of disease-free plantlets and the application of nutritional enhancement protocols, such as selenium (Se) biofortification, an essential mineral for human health. Selenium deficiency is associated with immunodeficiency, hypothyroidism, reduced fertility, cardiovascular disorders and some types of cancer. Biofortification strategies have shown positive results in crops such as rice, wheat and beans, but knowledge gaps remain regarding their effects on sweet potato during in vitro culture. This study aimed to evaluate biometric traits, photosynthetic pigments, DNA content, survival rate and Se accumulation in sweet potato cultivars micropropagated under diferente Se sources and concentrations. Three independent experiments were conducted in a completely randomized design using the cultivars Campina, Italiana-branca and Brazlândia- branca supplemented with sodium selenite or sodium selenate (0, 5, 10, 15, 20 and 25 μmol L−1). In Chapter 1, cv. Campina showed greater shoot length, number of green leaves and fresh biomass at 5 μmol L−1 of selenite, whereas leaf senescence increased at 25 μmol L−1. Selenium accumulation increased proportionally with concentration, and moderate doses preserved epidermal integrity. In Chapter 2, cv. Campina exhibited the best biometric responses between 0–5 μmol L−1, while Italiana-branca responded positively up to 10 μmol L−1. Campina accumulated higher Se levels in shoots and roots, indicating greater absorption and distribution capacity. In Chapter 3, cv. Brazlândia-branca showed enhanced growth and photosynthetic pigment content between 10–15 μmol L−1 of selenate, whereas selenite promoted Se accumulation mainly in roots. Nuclear DNA quantification by flow cytometry confirmed that none of the Se sources or concentrations compromised genomic stability, and ex vitro survival was high. Selenium supplementation during micropropagation proved effective in improving early plantlet performance and promoting controlled Se accumulation, varying according to cultivar, source and concentration. Low to moderate Se doses (5–10 μmol L−1) favored growth, and the differential accumulation patterns highlight the potential of sweet potato for future biofortification strategies.