Pre-germination treatments (seed priming) represent the physiological methods that improve plant production by modulating the metabolic activities of germination before the emergence of the radicle. The priming of seeds allows the dormancy-breaking, acceleration and synchronization of germination as well as a better growth, an earlier flowering, a greater tolerance to abiotic stress and higher yields. In this presentation, we summarize our studies about this subject in order to understand the mechanisms involved in seed priming.

1. SEED PRIMING: BENEFITS AND MECHANISMS
Lilya BOUCELHA, Ouzna ABROUS-BELBACHIR and Réda DJEBBAR*
Université of Science and Technology Houari Boumediene (USTHB), Algiers, Algeria
*rdjebbar@usthb.dz reda_djebbar@yahoo.fr
9th International Conference on Biotechnology and Environmental Management (ICBEM 2019)
#S1004 A
1-What’s priming
Seed priming is a method in which seeds are
hydrated (control hydration or uncontrolled
hydration) and dried to original moisture content
but the actual emergence of radicle is prevented.
2-Type of seed priming methods
Hydropriming : It is a seed priming method which involve priming of seed in pure water to initiate pre-
germinative physiological activity of seed but without radicle emergence, seeds are dried to original
moisture content before sowing.
Osmopriming : Osmopriming is one of the type of seed priming in which seeds are mixed with osmotic
agents of high molecular weight (Poly Ethylene Elycol) with different osmotic potential and have control
on level of hydration i.e. controlled hydration. Generally used osmotic agent is PEG 6000 and PEG 8000.
Chemopriming : Chemopriming involve the use of various chemicals to invigour the seeds.
Halopriming : In Halopriming, seeds are dipped in various salt solution e.g. Nacl.
Hormopriming : Seeds are primed in a solution containing phytohormones (gibberellic acid, salicylic
acid, auxines…).
Solid matrix priming : Solid matrix priming is a type of seed priming in which seeds are mixed with solid
materials and water.
Biopriming : Biopriming is also a type of priming in which seeds are primed in a solution containing bio-
control agents (bacteria).
3-Benefits: based on results obtained on Vigna unguiculata with hydropriming and osmopriming as examples
Germination and emergence
Growth and development
Tolerance to abiotic stress
Control Osmopriming (PEG 30%) Simple hydropriming Double hydropriming
Dormancy breaking, improvement
of germination and vigour,
homogenization (synchronization) of
germination
Better growth and earlier
flowering
Tolerance to abiotic
stresses such as drought
3-Mechanisms: based on results obtained on Vigna unguiculata and hypotheses
Seed priming causes biochemica and molecular changes (Heydecker et
al. 1973; Bradford 1986; Beckers et al. 2009; Boucelha and Djebbar
2015; Boucelha et al, 2019). Our results showed modification of
enzyme’s activities including those involved in the degradation of
reserves (alpha amylase, ...) and the scavenging of ROS (SOD, APX, CAT,
GPOX). The concept of oxidative window for germination proposed
by Bailly et al. (2008) could also explain the improvement of
germination performance of primed seeds. According to this theory,
oxidative stress was essential for triggering germination. ROS were
produced continuously during seed development, from
embryogenesis to germination. They play a dual role in the physiology
of seeds by being involved in the pathways of cell signaling on one
hand and acting as toxic products accumulated under stress
conditions, on the other hand.
Consequences on the whole plant
Epigenetic ?
Seed priming latent signaling
components that will be used
during a re-exposure to a stress.
This has
memory”
been called “plant
and corresponding to
acclimation. Our hypothesis is that
if an epigenetic mechanism is
in the improvement of
development and
of biotic and abiotic
involved
growth,
tolerance
stress.
Conclusion
On-farm seed priming (particularly hydro-priming), low-cost technique can significantly be helpful in order to obtain good crop establishment in many crops,
improving yield and inducing tolerance to stresses like drought.