Selenium (Se) is an essential micronutrient for human health due to its antioxidant capabilities. The Se content around the world is highly variable from 0.005 mg kg(-1) in areas from China and Finland to 8,000 mg kg-1 in seleniferous soils from Tuva-Russia. However, about one billion of people in the world wide are Se deficient. During the last decade, studies related with strategies for Se biofortification in food plants for human nutrition have significantly increased because this metalloid is incorporated into human metabolism mainly as a constituent of food plants. Similarly, Se biofortification is important in pastures for increasing the Se content in cattle to enrich meat and to prevent disease associated to Se deficiency as white muscle disease. In China, two endemic diseases have been related to Se deficiency: Keshan and Keshin-Beck diseases. Agronomic biofortification by using inorganic Se sources is a current practice in countries as China, Finland, and USA. In Chile, fertilization by using chemical compounds with Se is an uncommon practice due the edaphoclimatic characteristics of Andisols, which represent around 60% of agricultural soils of southern Chile. Recent studies showed that microorganisms as bacteria and arbuscular mycorrhizal fungi play an important role in the transformations and Se availability, representing an interesting biotechnological alternative to Se biofortification. This review is focalized to describing Se behavior in soil-plant system and the possible strategies to improving Se content, including the use of microorganisms as biotechnological tools for increasing plant nutrition and quality. Specific attention will be devoted to volcanic soils of Southern Chile, where different factors concur to enhance the Se-deficiency problem.