High salinity impacts germination of the halophyte Cakile maritima but primes seeds for rapid germination upon stress release

Abstract

Seed germination recovery aptitude is an adaptive trait of overriding significance for the successful establishment and dispersal of extremophile plants in their native ecosystems. Cakile maritima is an annual halophyte frequent on Mediterranean coasts, which produces transiently dormant seeds under high salinity, that germinate fast when soil salinity is lowered by rainfall. Here, we report ecophysiological and proteomic data about (1) the effect of high salt (200 mM NaCl) on the early developmental stages (germination and seedling) and (2) the seed germination recovery capacity of this species. Upon salt exposure, seed germination was severely inhibited and delayed and seedling length was restricted. Interestingly, non-germinated seeds remained viable, showing high germination percentage and faster germination than the control seeds after their transfer onto distilled water. The plant phenotypic plasticity during germination was better highlighted by the proteomic data. Salt exposure triggered (1) a marked slower degradation of seed storage reserves and (2) a significant lower abundance of proteins involved in several biological processes (primary metabolism, energy, stress-response, folding and stability). Yet, these proteins showed strong increased abundance early after stress release, thereby sustaining the faster seed storage proteins mobilization under recovery conditions compared to the control. Overall, as part of the plant survival strategy, C. maritima seems to avoid germination and establishment under high salinity. However, this harsh condition may have a priming-like effect, boosting seed germination and vigor under post-stress conditions, sustained by active metabolic machinery.

Germination responses of Mediterranean populations of Cakile maritima to light, salinity and temperature

“…NaCl decreased the germination percentage. This is consistent with other researches showing the saltsensitivity of C. maritima during seed germination (Debez et al 2004(Debez et al , 2018Megdiche et al 2007;Ghars et al 2009). High salinity inhibits and delays germination (Debez et al 2018) generating unfavourable osmotic conditions which prevent seed imbibition (Ghars et al 2009).…”

“…Many studies documented that high saline condition only induced secondary dormancy, as non-germinated seeds remained viable, showing complete germination recovery upon salt stress removal, or appearing viable when cut opened (e.g. Del Vecchio et al 2012, 2013Murru et al 2017;Debez et al 2018). In some halophytes, salinity exposure can even promote germination recovery (Muñoz-Rodríguez et al 2017).…”

“…Although its growth at vegetative stage and seed production are enhanced at moderate salinity (NaCl 50-100 mM; Davy et al 2006;Debez et al 2006Debez et al , 2012, this species is salt-sensitive during the germination phase (Debez et al 2004(Debez et al , 2008(Debez et al , 2018Megdiche et al 2007;Ghars et al 2009). While the ecology of the species has been investigated in depth (Davy et al 2006;Megdiche et al 2008;Debez et al 2013;Ben Hamed-Laouti et al 2016;Houmani and Corpas 2016;Belghith et al 2018), the response to salinity has been mainly analysed for Tunisian populations (Debez et al 2004(Debez et al , 2008(Debez et al , 2012(Debez et al , 2018Megdiche et al 2007;Ghars et al 2009), while other areas of the Mediterranean Basin received less attention. Moreover, the interaction with other environmental factors such as temperature and salinity has often been overlooked, except for England, where GA 3 -treated seeds were found to be less sensitive to salinity at the optimal germination temperature of 20°C (Ignaciuk and Lee 1980).…”

Physiological and Biochemical Analyses of Sorghum Varieties Reveal Differential Responses to Salinity Stress

“…Higher salt stress retards seed germination and root emergence and leads to poor crop establishment which is deleterious and prevents the plant in maintaining their proper nutritional requirements necessary for their healthy growth [3]. Reduced germination is the consequence of either direct toxic effect of salt or the general delay of the germination process caused by osmotic stress [4].…”

Tuzluluk Stresi altında Lathyrus sativus L.'nin Çimlenme ve Büyümesini İyileştirmede, Salisilik Asit ile Tohum Priming Uygulaması

“…It is possible that SA stimulates the seed germination via bio-synthesis of gibberellic acid and acts as thermogene inducers (Shah, 2003). The reduced MGT in SA primed seeds may be attributed to the increased water uptake and promotion of the biological processes during germination provoked by SA in those seeds (Debez et al, 2018), and the reduced accumulation of Na + and Clˉ ions by SA application (Jini and Joseph, 2017). Entesari et al (2012) reported the same effect on the mung bean grown under salinity stress and primed with SA.…”