Assessment of the Value of Stomatal Size and Density as Hallmarks of Nonaploid Kiwifruit Plants

In vitro-derived plants with elevated ploidy levels can display distinguishing features from the plants they are derived from, especially owing to their indirect regeneration. Genome size affects cell size and, thus, affects plant morphological characteristics. Therefore, stomata traits may be used as a diagnostic feature allowing identification of ploidy. Actinidia chinensis var. deliciosa A. Chev. (A. Chev.), known as kiwifruit, is successfully cultured in vitro and redifferentiated into plants via endosperm-derived calli. To identify differences between hexaploids obtained from seeds and confirmed nonaploids obtained from endosperm-derived calli, we analyzed the stomata. Our results confirmed that ploidy coincides with mean stomatal length, width, and density. Despite this correlation, this method cannot be used to distinguish individual hexaploid kiwifruit plants from nonaploid ones because samples with different ploidy yielded overlapping measurements.