Overexpression of a Medicago truncatula stress-associated protein gene (MtSAP1) leads to nitric oxide accumulation and confers osmotic and salt stress tolerance in transgenic tobacco.

The impact of Medicago truncatula stress-associated protein gene (MtSAP1) overexpression has been investigated in Nicotiana tabacum transgenic seedlings. Under optimal conditions, transgenic lines overexpressing MtSAP1 revealed better plant development and higher chlorophyll content as compared to wild type seedlings. Interestingly, transgenic lines showed a stronger accumulation of nitric oxide (NO), a signaling molecule involved in growth and development processes.

A stress-associated protein containing A20/AN1 zing-finger domains expressed in Medicago truncatula seeds.

MtSAP1 (Medicago truncatula stress-associated protein 1) was revealed as a down-regulated gene by suppressive subtractive hybridization between two mRNA populations of embryo axes harvested before and after radicle emergence. MtSAP1 is the first gene encoding a SAP with A20 and AN1 zinc-finger domains characterized in M. truncatula.

ABA-mediated inhibition of germination is related to the inhibition of genes encoding cell-wall biosynthetic and architecture: modifying enzymes and structural proteins in Medicago truncatula embryo axis.

Radicle emergence and reserves mobilization are two distinct programmes that are thought to control germination. Both programs are influenced by abscissic acid (ABA) but how this hormone controls seed germination is still poorly known. Phenotypic and microscopic observations of the embryo axis of Medicago truncatula during germination in mitotic inhibition condition triggered by 10 microM oryzalin showed that cell division was not required to allow radicle emergence.