Effect of abscisic acid and jasmonic acid on partial desiccation of encapsulated somatic embryos of sugarcane

Embryogenic calli of sugarcane (Saccharum sp. hybrid, clone CP52-43), with somatic embryos in the late scutelar stage, were subjected to different treatments for increasing embryo tolerance to desiccation. The medium was supplemented with abscisic acid (ABA) (3.8 μM), jasmonic acid (JA) (4.7 μM) or a combination of them. A control treatment without growth regulators was also included. The embryos were encapsulated in alginate beads and dehydrated or not in sucrose (0.5 M). Thereafter, they were further dehydrated in chambers containing silicagel until the beads reached either 60% or 30% of water content (WC). Survival of encapsulated-dehydrated embryos was achieved only in the control and ABA treatment. ABA induced an increase in protein, polyamines, free proline levels and starch levels as a response to desiccation tolerance. JA treatment showed the lowest protein and polyamines levels and increased the starch content almost two-fold compared to the ABA treatment. The JA treatment induced high levels of 4-methylcatechol and the lowest levels of gallic acid. However, the ABA treatment increased gallic acid and p-coumaric acid content in the induction medium. Some differences were found in growth regulator free-medium in relation to the induction medium. JA is not effective in these desiccation processes. The mechanisms by which these two plant growth regulators act on the induction of tolerance to stress are presumably different.