Different acclimatization mechanisms of two grass pea cultivars to osmotic stress in in vitro culture
Acta Physiol Plant
Different acclimatization mechanisms of two grass pea cultivars to osmotic stress in in vitro culture
Barbara Piwowarczyk 0
Aneta Łukasiewicz 0
Krzysztof Tokarz 0
Wojciech Makowski 0
0 Unit of Botany and Plant Physiology, Institute of Plant Biology and Biotechnology, Faculty of Biotechnology and Horticulture, University of Agriculture in Krakow , Al. 29 Listopada 54, 31-425 Krako ́w , Poland
Grass pea (Lathyrus sativus L.) is a legume crop known from its tolerance to various abiotic stresses, especially drought. In this study, we investigated: (1) the response of grass pea seedlings to osmotic stress generated in vitro by polyethylene glycol (PEG); (2) potential drought acclimatization mechanisms of two polish grass pea cultivars. Grass pea seeds of two cultivars were sown on media containing different PEG concentrations (0, 5.5, 11.0 mM) and cultivated for 14 days in controlled conditions. Plants' dry matter increased under osmotic stress (regardless of PEG concentration). In turn, the highest dose of PEG caused a reduction in seedling growth in both cultivars. Furthermore, PEG caused the peroxidase activity increase in whole seedlings and catalase (CAT) activity in roots. However, differences between cultivars were noted in: CAT activity in shoots; while phenols and anthocyanin content as well as electrolyte leakage in shoots and roots. In turn, in both tested genotypes, accumulation of proline increased in shoots under osmotic stress. Obtained results indicate that the examined plants, although belonging to the same species, differ in acclimatization processes leading to elevated tolerance to osmotic stress.
Catalase; Drought; Lathyrus sativus; Polyethylene glycol; Peroxidase; Proline
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Water scarcity, a worldwide problem currently is expected
to elaborate in the near future (Dai 2013). Water shortages
negatively influence plant growth and development,
consequently heavily limit plant productivity. A search for
plant species that are tolerant to drought and elucidating
the mechanisms of their responses to osmotic stress is of
significant importance. Grass pea (Lathyrus sativus,
Fabaceae) is a crop highly tolerant to the stress caused by
various abiotic factors (Vaz Patto et al. 2006). Even though
the exact mechanism of this tolerance is still not known,
there are reports indicating that it can rely on the ability to
adjust the plants osmotic potential (Jiang et al. 2013;
Piwowarczyk et al. 2014), elevated antioxidant enzyme
activity (Jiang et al. 2013), accumulation of polyamines
and b-N-oxalyl-L-a,b-diaminopropionic acid (Xing et al.
2001; Xiong et al. 2006).
In response to water stress, plants adjust their
metabolism utilizing different mechanisms. However, considering
the complexity of these mechanisms, we are far from
gaining a comprehensive understanding of abiotic plant
tolerance, despite many years of research (Farooq et al.
2009). Additionally, osmotic stress leads to the formation
of reactive oxygen species (ROS). ROS impede the normal
functioning of cells by degrading/inactivating proteins,
lipids, and DNA (Blokhina et al. 2003), and inter alia
severely damage cell membranes (Ashraf and Ali 2008).
Plant defense against oxidative stress is based on the
antioxidant system (Farooq et al. 2009). Earlier studies
showed that the mechanism of salinity tolerance in grass
pea plants resulted probably from the elevated activity of
antioxidant system in the root cells, manifested by
increased accumulation of phenolic compounds and
peroxidase activity (Piwowarczyk et al. 2016).
The aim of this study was to investigate the response of
grass pea seedlings to osmotic stress generated in vitro and
identification of potential drought acclimatization
mechanisms of this species, in relation to different cultivars.
Materials and methods
Plant material and culture conditions
Plant material comprised of grass pea cultivars: ‘Derek’
and ‘Krab’. Derek and Krab were introduced to Polish
Register of Original Varieties in 1997 and are the only two,
registered, Polish cultivars (Milczak et al. 2001). Both
cultivars yield 3.0 t/ha. Cultivars differ from each other in
seed size and morphology (Derek: small, creamy-green;
Krab: medium, creamy), thousand seed mass (D 124 g, K
184 g) and seed protein content (D 31%, K 28%) (Cichy
and Rybin´ ski 2007). There is a lack of information
concerning differences in resistance to biotic and abiotic
stresses between the studied cultivars. Seeds were surface
sterilized according to Piwowarczyk et al. (2016).
Sterilized seeds were placed on phytagel solidified (0.5%) MS
macro and microelements’ medium (Murashige and Skoog
1962). To induce osmotic stress, polyethylene glycol
(PEG-6000, Duchefa Biochemie) in different concentration
(0, 5.5, 11.0 mM) was added to basal medium. Vessels
with seeds were placed under controlled conditions (light:
16/8 h photoperiod, 50 lmol/m2/s1 photosynthetic photon
flux density, temperature: 25 ± 1 C).
Determination of biometric (...truncated)