Growth and Morphogenesis of Azuki Bean Seedlings in Space during SSAF2013 Program

Abstract

S e e dlings of a zuki be an we re cultivate d und e r micro gravit y condit ions in sp ac e during SSAF2013 program, and then growth, morphology, and the cell wall rigidity of their etiolated epicotyls were analyzed. Epicotyls g r o w n o n t h e g r o u n d o r i e n t e d ve r t i c a l direction, whereas epicotyls grown in space oriented oblique upward direction away from the cotyledons. The length of epicotyls grown in space was varied, but the proportion of seedlings with larger epicotyls was higher than that of the controls. These results indicate that growth and morphology of epicotyls are modified under microgravity conditions in space. On the other hand, the breaking load of epicotyls was analyzed using a spring balance for determination of the cell wall rigidity of epicotyls. The breaking load of epicotyls grown in space tended to be smaller than that of controls. Also, epicotyls grown in space had resistance to bending than the controls. Thus, microgravity affected the cell wall rigidity of epicotyls. Taken together, azuki bean seedlings performed an automorphogenesis and cell wall modification under microgravity conditions. Under microgravity conditions, where plants need not to resist the gravitational force, the body shape and the cell wall rigidity of stems may be modified

Modification of growth anisotropy and cortical microtubule dynamics in Arabidopsis hypocotyls grown under microgravity conditions in space

“…The morphology of shoots has been examined in various space experiments. Wheat coleoptiles, pea epicotyls and azuki bean epicotyls oriented in the abaxial direction (Heathcote et al , Ueda et al , Soga et al ), rice coleoptiles bent in the adaxial direction (Hoson et al , Wakabayashi et al ), cucumber hypocotyls elongated straight in predetermined direction (Takahashi et al ), whereas Arabidopsis hypocotyls elongated in various directions (Figs and , Hoson et al ). These results indicate that the growth pattern of shoots under microgravity conditions in space varies by plant species and by the type of organs.…”

Roles of MAP65-1 and BPP1 in Gravity Resistance of Arabidopsis hypocotyls

“…Plants generally had a shorter and thicker body under hypergravity conditions (Soga, 2010(Soga, , 2013. On the other hand, plant developed a long and thin body under microgravity conditions in space Soga et al, 2002Soga et al, , 2014. The body shape of Arabidopsis varied in proportion to the logarithm of the magnitude of gravity in the range from microgravity to hypergravity (Soga et al, 2001).…”

“…Plants developed a short and thick body under hypergravity conditions (Hoson et al, 1996;Soga et al, 1999aSoga et al, , 1999bSoga et al, , 2001Wakabayashi et al, 2005;Nakano et al, 2007). On the other hand, plant body became longer and thinner under microgravity conditions in space (Soga et al, 2001(Soga et al, , 2014Hoson et al, 2002). Therefore, modification of body shape in response to the magnitude of the gravitational force is considered as a key part of gravity resistance.…”

Centrifugal displacement of nuclei in epidermal cells of azuki bean epicotyls

“…Based on the results of hypergravity experiments, it was hypothesized that plant body would become longer and thinner under microgravity conditions in space. This hypothesis was proven by space experiments such as STS-95 Rice and Aniso Tubule (Hoson et al, 2002(Hoson et al, , 2014Soga et al, 2002Soga et al, , 2014Soga et al, , 2018a. The development of a short and thick body is considered as a key part of the response that enables plants to grow against the gravitational acceleration.…”