EFFECT OF WEIGHTLESSNESS ON THE DISTRIBUTION OF CALCIUM IN THE STATOCYTES OF RAPESEED
ROOTS, BRASSICA NAPUS (POLCA)
Research Area: Plant Biology
Expedition(s): 18
Principal Investigator(s): ● Valerie Legué, Clermont Université, Université Blaise-Pascal,
Aubiere, France
RESEARCH OBJECTIVES
The objective of the Effect of weightlessness on the distribution of calcium in the statocytes of
Rapeseed roots, Brassica napus (Polca) experiment is to analyze the effect of change in
amyloplasts-ER interactions on calcium dependent pathways.
RESULTS
The Polca experiment was
conducted using Brassica napus
seedlings, which submitted 4
different conditions:
continuously on 1 g centrifuge
or continuously in microgravity
conditions. Some seedlings that
germinated on centrifuge for 28
hours were transferred for 10
minutes into microgravity
conditions, leading to a loss of
amyloplast-ER interactions
through amyloplasts
displacement. Others seedlings that germinated in microgravity conditions for 28 hours were
transferred to a centrifuge for 10 minutes.
One hundred percent of seed germination was obtained in all conditions. The analysis of
amyloplast positioning (ESA Figure 1) showed clearly (1) a relocalization of amyloplast in
statocytes of seedlings grown microgravity conditions compared to those grown on 1 g
centrifuge; (2) a slight amyloplast displacement after 10 minutes of transfer. Surprisingly,
despite the slight amyloplast displacement, a change in the number of calcium precipitation is
revealed after each transfer. These results suggested that the calcium signaling seemed to be
affected by a slight amyloplast displacement. The presence of a gravi-receptor near the
amyloplast was then hypothesized.
This investigation is complete; however additional results are pending publication.
Amyloplasts distribution (A) and number of calcium precipitates (B) in
statocytes of seedling roots grown in microgravity condition (mg), on 1-g
centrifuge in space (1 g, space control), in microgravity for 28 hours and
then transferred during 10 minutes on the centrifuge (mg + 1 g), or on 1 g
centrifuge for 28 hours and transferred to microgravity condition for 10
minutes (1 g + mg). The relative distribution of amyloplasts is indicated by
a color scale from yellow to red. ESA image.