Calcium dynamics and modulation in carrot somatic embryogenesis

Abstract

Free calcium (Ca2+) is a pivotal player in different in vivo and in vitro morphogenic processes. In the induction of somatic embryogenesis, its role has been demonstrated in different species. In carrot, however, this role has been more controversial. In this work, we developed carrot lines expressing cameleon Ca2+ sensors. With them, Ca2+ levels and distribution in the different embryogenic structures formed during the induction and development of somatic embryos were analyzed by FRET. We also used different chemicals to modulate intracellular Ca2+ levels (CaCl2, ionophore A23187, EGTA), to inhibit calmodulin (W-7) and to inhibit callose synthesis (2-deoxy-D-glucose) at different times, principally during the first stages of embryo induction. Our results showed that high Ca2+ levels and the development of a callose layer are markers of cells induced to embryogenesis, which are the precursors of somatic embryos. Disorganized calli and embryogenic masses have different Ca2+ patterns associated to their embryogenic competence, with higher levels in embryogenic cells than in callus cells. The efficiency of somatic embryogenesis in carrot can be effectively modulated by allowing, within a range, more Ca2+ to enter the cell to act as a second messenger to trigger embryogenesis induction. Once induced, Ca2+-calmodulin signaling seems related with the transcriptional remodeling needed for embryo progression, and alterations of Ca2+ or calmodulin levels negatively affect the efficiency of the process.

Organelle Ca2+/CAM1‐SELTP confers somatic cell embryogenic competence acquisition and transformation in plant regeneration

“…Ca 2+ is known to induce and regulate the expression of CAM and CAM‐like proteins that are players in Ca 2+ ‐mediated signal transduction (Anil & Rao, 2000). The efficiency of SE in plants can be effectively modulated by allowing, within a range, additional Ca 2+ to enter the cell to act as a second messenger to trigger embryogenesis induction (Anil & Rao, 2000; Calabuig‐Serna et al ., 2023). It has been reported that Ca 2+ levels increased in the cells of the regions where somatic embryos will be formed, thereby constituting early markers of the embryogenic regions (Denninger et al ., 2014; Calabuig‐Serna et al ., 2023).…”

“…The efficiency of SE in plants can be effectively modulated by allowing, within a range, additional Ca 2+ to enter the cell to act as a second messenger to trigger embryogenesis induction (Anil & Rao, 2000; Calabuig‐Serna et al ., 2023). It has been reported that Ca 2+ levels increased in the cells of the regions where somatic embryos will be formed, thereby constituting early markers of the embryogenic regions (Denninger et al ., 2014; Calabuig‐Serna et al ., 2023). Meanwhile, altering Ca 2+ signaling by reducing their levels or interfering with CAM has a significantly negative impact on embryogenesis induction (Calabuig‐Serna et al ., 2023).…”

“…It has been reported that Ca 2+ levels increased in the cells of the regions where somatic embryos will be formed, thereby constituting early markers of the embryogenic regions (Denninger et al ., 2014; Calabuig‐Serna et al ., 2023). Meanwhile, altering Ca 2+ signaling by reducing their levels or interfering with CAM has a significantly negative impact on embryogenesis induction (Calabuig‐Serna et al ., 2023). In the current study, to identify the effect of Ca 2+ ‐dependent CAM1 activity on embryogenic differentiation, the CAM1 ‐OE transgenic line was treated with Ca 2+ inhibitor.…”

Characterisation and Expression Analysis of LdSERK1, a Somatic Embryogenesis Gene in Lilium davidii var. unicolor

“…To date, most studies have investigated the mechanisms of SE process induction using model plant species such as Arabidopsis thaliana [ 15 ], carrot [ 16 ], alfalfa [ 17 ], maize [ 18 ] and rice [ 19 ]. Lilies are monocotyledons of the Liliaceae and are the most important bulb crops [ 20 ].…”