Morphological and histological description of the development of microtubers of the genus Dioscorea (Dioscoreaceae)

Microtubers constitute a production alternative to tuber segmentation, storage, and sowing in traditional cultivation systems. Despite existing studies on the conditions necessary for production, descriptive analyses are scarce and have focused on the starches present in microtubers. To address the lack of information, this study aimed to describe the primary stages of microtuber development and the anatomical changes during each stage in different Dioscorea species and varieties produced under in vitro conditions. Forty microtubers were processed by differential staining using the Feulgen method and analyzed by confocal microscopy. The results describe the formation of the main microtuber segments and developmental stages, as well as the formation of the conduction systems within the microtuber, the start of starch granule accumulation, and the different cells of microtuber tissue. In addition, morphological differences were observed in the microtubers derived from Dioscorea sparsiflora, which exhibited an elongated, thickened root-like appearance, in contrast to the microtubers of Dioscorea alata, which were spherical to ovoid in shape and displayed a slight purple hue.