Primavera otoño 2020 (Año LXIII Núms. 122-123) Año LXIV Núm. 124-125 horizontes PRIMAVERA / OTOÑO 2021 PUCPR 76 IN VITRO PROGRESS OF ORGANOGENESIS OF CITRUS × LATIFOLIA Jose L. Mercado Rivera Pontifical Catholic University of Puerto Rico Neuroscience Master’s Degree Program Abstract Citrus is vital in the food industry; its fruit is an essential source of vitamins, acids, and aromatic compounds. The demand for citrus cultivars increased during the last year because of plant disease, and manufactured products. Farmers increased the culture of Citrus x latifolia (Persian lime) because of its high demand due to the antioxidants content, ascorbic acid, citric acid, and flavonoid compounds. The demand for improved genetic material, and disease-free plants were the main problems that plant tissue culture techniques needed to solve. Biotechnology provided the necessary molecular tools to improve in vitro propagation during the last decade. Micropropagation is an in vitro technique producing identical clones yielding quality plants via organogenesis. Direct and indirect organogenesis used a medium with plant growth regulators, which could be utilized in a bioreactor by immersing multiple-node samples. Temporary immersion technology allowed high multiplication rate per explant and production of biological compounds. Introduction In vitro propagation, known as micropropagation, uses plant tissue to begin an in vitro process to propagate many new plants. Established at the beginning of the 20th century, in vitro propagation has been an essential tool for physiological research, developing disease- free plants, germplasm conservation, genetic transformation, and extraction of essential biological compounds (Pandey & Tamta, 2016). Researchers sterilize plant tissue to eradicate pathogens and, using aseptic techniques, in vitro cultured the tissue in a nutrient media to regulate the growth of new organs (Lazo- Javalera et al., 2016). Micropropagation is the multiplication of plants, producing disease- resistant clones through soma clonal variation (Salis et al., 2017). These advances in plant tissue culture help reestablish citrus crops damaged by diseases, such as citrus canker and the citrus tristeza virus. Oranges, mandarins, and lemons are the citrus fruits sold worldwide because of their high consumption as fresh fruit, juice, and their application in manufacturing products (Singh et al., 2018). The demand for Persian lime Citrus × latifolia has increased because of its high antioxidants, ascorbic acid, citric acid, vitamins, and flavonoid compounds. New crops rise the need for disease-free plants and true-type producers. Traditional methods using seeds developed from sexual propagation do not guarantee a stable genetic framework or guarantee plants disease free. The development of in vitro propagation protocol of Citrus × latifolia encounter the following challenges: sterilization step difficulties, negligible shoots multiplication rate, leaf abscission, and slow organogenesis (Bulbarela-Marini et al., 2019). New technologies utilize new phytohormones to regulate organogenesis, control tissue culture vessel microenvironments and evaluate tissue age before propagation (Aremu et al., 2017). The new temporary immersion technique provides greater shoot multiplication and extraction of biochemical compounds using liquid media bioreactors (Pramita et al., 2018). Technologies include novel hormones, in vitro control, and biotechnological tools to improve organogenesis in citrus micropropagation protocols.