Sugarcane (Saccharum spp.) is one of the most important raw materials for Brazilian economy, unique in its ability to accumulate large amounts of sucrose in the stalk. The ripening stage is crucial in agronomic terms, influencing harvesting season, milling operations, and very importantly sucrose yield itself. Despite sugarcane being an excellent model for studying source-sink relationship - synthesis of sucrose in the leaves (source) and accumulation in the internodes (sink) - little is known about the molecular hormonal and developmental regulation of this process. Several plant growth regulators or ripeners, analogous to plant hormones, like ethylene, are commonly applied to sugarcane fields to increase sucrose accumulation, accelerate ripening or inhibit flowering. Ethylene is also identified as the key internal cue that regulates the transition from active vegetative growth to cane maturation (and ripening) phase. With ethylene being one of the most commercially successful hormones used for manipulating sugarcane ripening, and that it is a natural primer for cane maturation, we aim to understand its synthesis and action in relation to sugar accumulation and ripening regulation, and how it can be manipulated to increase sugar yield and crop productivity. We investigate this topic by three different but complementary approaches: (i) identify the key (regulatory) genes (via transcriptome analysis) that are modulated by ethylene during sugarcane ripening and understand how they regulate sucrose accumulation and plant growth; (ii) identify promoters and their regulators of genes encoding the enzyme 1-aminocyclopropane-1-carboxylic acid synthase (ACS), the regulatory enzyme in the biosynthesis of ethylene, to gain molecular insight into the regulation of ethylene in relation to cane ripening; and (iii) characterize functionally the sugarcane gene encoding the DELLA protein, the main integrator of ethylene and gibberellin actions and plant growth and development, and evaluate its role in source-sink regulation using transgenic sugarcane plants with its up- and down-regulation. These studies will expand our understanding of the physiological, molecular and developmental mechanisms involved in sucrose accumulation, contributing to future breeding programs and biotechnological improvement of sugarcane. (AU)
Articles published in Agência FAPESP Newsletter about the research grant:
TAVARES, RAFAEL GARCIA;
SOARES, JOSE SERGIO;
ScGAI is a key regulator of culm development in sugarcane.
Journal of Experimental Botany,
JUL 20 2018.
Web of Science Citations: 6.