Natural variation of elaiosome and seed traits in Coreanomecon hylomeconoides Nakai in Korea

Abstract

The myrmecophytes are plants which have mutualistic relationship with ants. They often have seeds with specialized lipid rich appendage, elaiosome. Ants can obtain nutrients from elaiosome, and seeds can be dispersed by ants to proper sites for germination. Previous studies suggested that the foraging behavior of ants likely depends on the size of diaspores and the fatty acid composition of elaiosomes. Notably, many plant species exhibit natural variation in the fatty acid composition of elaiosome among populations, but no information is available in Korean endemic myrmecophytes. As a first step to explore the interaction between Korean myrmecophytes and ant, we examined seed morphology and the fatty acid composition of elaiosomes in Coreanomecon hylomeconoides Nakai in seven populations. Seed morphology was measured including seed length, elaiosome length, seed mass, elaiosome mass and each ratio (E/S ratio). The elaiosomes were removed from the collected seed, and the fatty acid components were analyzed using GC-MS. In the morphological results, we found that the variation of elaiosome traits affected to E/S ratio traits. Because E/S ratio is related to energy balance between consumption and acquisition, we suggested that C. hylomeconoides should be changed the trait for ants. In the chemical traits, variation of concentration also showed significant differences in some fatty acid methyl ester species. For multivariable and cluster analysis, we found Gwangju population was separated from other population remarkably. Remained other six population showed weak clusters. This trend was thought by closed distance between populations, but it did not have significant correlation with geographic distance. Diaspore is dispersed by ants, so the traits should be related to traits of ant community in populations. However, the traits also can be affected by other things. Trait variation of myrmecophytes’ seeds are expected to be related these factors, and we should study more about them.