Effect of simulated microgravity on seedling development and vascular differentiation of soy

Vascular differentiation influences not only the correct functionality of water transport system, but it also affects the softness of tissues, food digestibility and hence its quality. The aim of this study is to investigate the effect of clinostat rotation on seedling growth and vascular differentiation of soy. Seeds are germinated either on a uni-axial clinostat or in 1g under different temperature regimes. Several parameters, namely percent germination, radicle length, and fresh and dry weights, were recorded. Anatomy of cotyledons, hypocotyl hook and hypocotyl was quantified through image analysis software programs. Vessel lumen area, cell wall thickness, area and shape of parenchyma cells, presence of endodermis, yield and distribution of storage substances were recorded. Our results showed that the development of well-structured seedlings was possible in a few days both in 1g and in simulated low-gravity. Overall analysis suggests that the vascular system in soy seedlings is slightly affected by clinostat rotation. Changes in the distribution of phenolics acted as an adaptive response to the stress of altered gravity. Moreover, anatomical analysis was a better method to evaluate the state of seedling hydration than overall morphology. (c) 2005 Elsevier Ltd. All rights reserved.