Karen Granados-Nava
A hydrophobic cuticle covers most plant surfaces and provides the first layer of defense from both abiotic and biotic environmental stresses. Cuticular lipids that accumulate on maize silks consist of mostly hydrocarbons and minor amounts of fatty acids (16 to 33 carbons in length), which are products and precursors of the hydrocarbon biosynthetic pathway, respectively. Previous work in inbred B73 has shown a 3- to 5-fold increase in hydrocarbon accumulation on silks that have emerged into the external environment as compared to the silks that remain encased by husk-leaves. Moreover, cuticular hydrocarbon load is 3-fold higher on emerged silks from B73 compared to inbred Mo17. However, it is unclear whether prior to silk emergence cuticular lipid accumulation is dynamic along the length of the silks or between genotypes. To assess this, we profiled cuticular lipids along the silk length from B73 and Mo17 at two different growth stages, either on the day silks would first emerge or three days after silks had emerged from the husk leaves. Silks were sectioned into three contiguous segments for encased tissues and two segments for emerged tissues, cuticular lipids were extracted, and then characterized via gas chromatography-flame ionization detection. We observe that cuticular lipid accumulation differs along the lengths of the silks, both at 0 days and at 3 days post-silk emergence (PSE). Although total accumulation is similar in encased tissues at 0 and 3 days PSE, the composition of the metabolome differs. For example, the relative abundance of fatty acids is lower in encased tissues at 3 days PSE, especially in inbred B73, which accumulates twice the amount of hydrocarbons products on emerged silks as compared to Mo17. This study will provide additional insights into product-precursor relationships within the metabolic network for cuticular lipid accumulation.
Duration: 04/29/2019