Development and Growth of Several Strains of Arabidopsis Seedlings in Microgravity

Abstract

Growth and development of dark-grown Arabidopsis thaliana seedlings were studied in microgravity during space shuttle mission STS-84. The major purpose of this project was to determine if there were developmental differences among the four ecotypes studied--Wassilewskija (Ws), Columbia (Col), Landsberg erecta (Ler), and C24--and to evaluate whether particular ecotypes are better suited for spaceflight experimentation compared with others. A secondary goal was to study the growth of three starch-deficient strains of Arabidopsis by extending the observations made in a previously published report. For all strains, seed germination was not affected by microgravity, but seedlings were smaller in the spaceflight samples compared with the ground controls. The starch-deficient strains continued to exhibit vigorous growth until the termination of the experiment at 121 h after imbibition of seeds. However, ethylene effects, i.e., reduced growth and exaggerated hypocotyl hooks, were observed in all strains studied. Nevertheless, the Ler and C24 ecotypes seem to be more suitable for spaceflight research, compared with the other two ecotypes, based on measurements of their relative and absolute growth. This type of information should aid in the design of plant experiments for the International Space Station.

Gravitropic moss cells default to spiral growth on the clinostat and in microgravity during spaceflight

“…The simplest prediction was that space-grown moss protonemata would default to a non-patterned, random distribution. Consistent with this idea, almost all darkgrown roots and shoots flown in microgravity have shown no predictable growth pattern (Perbal and DrissEcole 1989;Johnsson et al 1996;Hoson et al 1999;Kiss et al 2000). Also, rhizoids of the green alga Chara, which like Ceratodon are gravitropic single cells, showed no apparent pattern to their distribution after 2 days in microgravity (Braun et al 1999).…”

“…But in other cases, rotation versus microgravity produce different responses such as in plant development, movement, and gene expression (Brown 1993;Link et al 2001). Another example is that Arabidopsis roots, which grow down when stationary, coil in clockwise spirals when rotated on a clinostat (Simmons et al 1995;Rutherford and Masson 1996), but not apparently in microgravity (Hoson et al 1999;Kiss et al 2000).…”

Nucleolar structure and proliferation activity of Arabidopsis root cells from seedlings germinated on the International Space Station

“…The cell proliferation equilibrium of the root meristem is altered, which results in smaller ''older'' seedlings (Antonsen and Johnsson, 1998;Kiss et al, 2000;Perbal, Fig. 6.…”

Space, the final frontier: A critical review of recent experiments performed in microgravity

“…Some interesting differences in growth were observed (Table 2) [42]. Most space-flight studies in recent years have focused on single genotypes of A. thaliana [15,17,19,43,44].…”

“…Means followed by different letters indicate statistical differences as determined by an ANOVA/Tukey test (P < 0.05). Table is modified from [42]. …”