Dealing with halophytes: an old problem, the same continuous exciting challenge

[EN] It¿s common sense to usually recognize some concepts as being very simple and accessible. Often, this could lead to a reductionist way in which some problems are regarded and understood. In plant ecology, many concepts are volatile and in nowadays we are using some of them mainly as standard definitions. But in the nature, there are no standards. Only a continuum flux of energy and stable instability that would imply caution and attention in the interpretation of ecological groups of plants. In this work we try to sensitize and pay attention to the complexity of some concepts in plant ecology, and to focus on halophytes, as an example of our intentionThis paper was published with support provided by the POSDRU/89/1.5/S/49944 project “Developing the innovation capacity and improving the impact of research through post-doctoral programmes”.Grigore, MN.; Toma, C.; Boscaiu, M. (2010). Dealing with halophytes: an old problem, the same continuous exciting challenge. Analele Stiintifice ale Universitatii "Alexandru Ioan Cuza" din Iasi. Biologie Vegetala. 56(1):21-32. http://hdl.handle.net/10251/101719S213256

Ecological implications of bulliform cells on halophytes, in salt and water stress natural conditions

[EN] Seven Romanian salt-tolerant species were histo-anatomical investigated. These species have been classified by the authors of the present study as ¿amphibious¿ halophytes, related to the field observations and anatomical considerations. All the analyzed taxa present bulliform cells at the foliar epidermis level. Despite the fact that there are different interpretations regarding the bulliform cells role and functional significance, we correlate these structures with the ecological factors, salinity and, respectively, drought conditions.This paper was published with support provided by the POSDRU project “Developing the innovation capacity and improving the impact of research through postdoctoral programmes”.Grigore, MN.; Toma, C.; Boscaiu, M. (2010). Ecological implications of bulliform cells on halophytes, in salt and water stress natural conditions. Analele Stiintifice ale Universitatii "Alexandru Ioan Cuza" din Iasi. Biologie Vegetala. 56(2):5-15. http://hdl.handle.net/10251/101713S51556

ENZYMATIC ACTIVITY AND SOLUBLE PROTEIN CONTENT IN SEEDLINGS OF CALENDULA OFFICINALIS L. UNDER SALT STRESS

[EN] Enzymatic activity and soluble protein content in relation to salt stress tolerance were investigated in Calendula officinalis seedlings after 24 days of treatment with different salt treatments, including NaCl, CaCl2, MgCl2 and mixtures of them. The marigold seedlings were used in order to investigate the possible salt-inducible responses and the possible alleviative role of calcium and magnesium salts in respect with adverse salinity conditions. Activity of superoxide dismutase (SOD; EC 1.15.1.1) and peroxidase (POD; EC 1.11.1.7) generally slightly decreased under salt treatments, with minor variations from the value recorded for control series and within applied treatments. Catalase (CAT; EC 1.11.1.6) activity was stimulated by NaCl salinity and MgCl2 addition; its activity was found to be lowest under calcium and magnesium chloride treatments solelyOprica, L.; Vicente Meana, Ó.; Boscaiu Neagu, MT.; Grigore, MN. (2016). ENZYMATIC ACTIVITY AND SOLUBLE PROTEIN CONTENT IN SEEDLINGS OF CALENDULA OFFICINALIS L. UNDER SALT STRESS. Journal of Plant Development (Online). 23:71-79. http://hdl.handle.net/10251/91887S71792

Characterizing the effects of salt stress in Calendula officinalis L

[EN] In this study the effects of salt stress on growth and several stress markers were investigated in the ornamental and medicinal plant Calendula officinalis. One-month-old plants were submitted to increasing salt concentrations, up to 150 mM NaCl, for a period of 30 days. Salinity affected growth in terms of relative reduction of stem length and fresh weight of the plants, but water content remained unchanged indicating a certain tolerance to low and mild NaCl concentrations. Although Na+ and Cl- increased in parallel to increasing salinity, the levels of K+ and Ca2+ showed no significant change, while Mg2+ levels recorded a twofold increase upon the ap- plication of the highest salt concentration. Other measured para- meters showed a more significant change, notably proline levels, which registered a nine-fold increase in the presence of 150 mM NaCl. In conclusion, although plants suffered from salt stress, as shown by the degradation of photosynthetic pigments and induction of oxidative stress (increased MDA levels), they continued their ve- getative growth under low concentrations of salt. The main mechanisms of response to salt stress in this species appear to be based on the maintenance of K+ and Ca2+ homeostasis and the accumulation of proline as a functional osmolyte.Kozminska, A.; Al Hassan, M.; Kumar, D.; Oprica, L.; Martinelli, F.; Grigore, MN.; Vicente, O.... (2017). Characterizing the effects of salt stress in Calendula officinalis L. Journal of Applied Botany and Food Quality. 90:323-329. doi:10.5073/JABFQ.2017.090.040S3233299

Do Halophytes Really Require Salts for Their Growth and Development? An Experimental Approach

[EN] Halophytes are salt-tolerant plants found exclusively in habitats with high levels of soil salinity. It is generally assumed that salt stress is the most important limiting factor for plant growth in natural saline environments, and that halophytes have developed specific adaptations to elevated salinity which make them unfitted to grow in the absence of salt, thus explaining their distribution in nature. To address experimentally this question, two halophytic species (Inula crithmoides L. and Plantago crassifolia Forssk.) and a maritime dune species (Medicago marina L.) were grown in the greenhouse for several weeks in different substrates: peat, vegetable garden soil, saline soil and sand from maritime dunes. Measurements of growth parameters-number of leaves, plant length, fresh and dry weights-showed that all three species grew much better on the salt-free and nutrient-rich substrates, peat and garden soil, than on saline soil and dune sand. These results indicate that salts are not compulsorily required for development of halophytic species, and suggest that limitation of water and nutrients, rather than soil salinity per se, are the most important restrictive factors for plant growth in saline habitats. The distribution of halophytes in nature is probably dependent on their limited ability to compete with glycophytes in non-saline areas, while remaining highly competitive under environmental conditions stressful for non-tolerant species.This work was funded by the Spanish Ministry of Science and Innovation (project CGL2008-00438/BOS), with contribution from the European Regional Development Fund. M.-N.G. acknowledges the support provided by the Romanian POSDRU/89/1.5/S/49944 project ‘Developing the innovation capacity and improving the impact of research through post-doctoral programmes’, and by COST Action FA0901: ‘Putting Halophytes to work-From Genes to Ecosystems’ for his stay in Valencia in the frame of a Short Term Scientific Mission.Grigore, MN.; Villanueva Lozano, M.; Boscaiu Neagu, MT.; Vicente Meana, Ó. (2012). Do Halophytes Really Require Salts for Their Growth and Development? An Experimental Approach. Notulae Scientia Biologicae. 4(2):23-29. https://doi.org/10.15835/nsb427606S23294

Ecological anatomy in halophytes with C4 photosynthesis: discussing adaptatve features in endangered ecosystems

[EN] The Chenopodiaceae halophyte species provide perhaps the ideal model to study the ecological adaptations in relations with extreme environmental conditions. Closely linked with saline habitats, the chenopods with Kranz anatomy represents a striking and intriguing example of coevolution. In this study, we investigate the Kranz anatomy in a holistic manner in halophytes vegetating in two nature reserves, here regarded as rare and endangered ecosystems. This issue, apart from its scientific interest – as an adaptive, ecological and evolutive feature – also suggests the compulsory necessity to protect these areas, in order to preserve the floristic diversity in such menaced ecosystemsThis paper was published with support provided by the POSDRU/89/1.5/S/49944 project “Developing the innovation capacity and improving the impact of research through post-doctoral programmes”.Grigore, MN.; Toma, C.; Zamfirache, M.; Boscaiu, M.; Olteanu, Z.; Cojocaru, D. (2012). Ecological anatomy in halophytes with C4 photosynthesis: discussing adaptatve features in endangered ecosystems. Carpathian Journal of Earth and Environmental Sciences. 7(2):13-21. http://hdl.handle.net/10251/78758S13217

Mitigation of Salt Stress-Induced Inhibition of Plantago crassifolia Reproductive Development by Supplemental Calcium or Magnesium

[EN] In Plantago crassifolia, a moderate halophyte characteristic of borders of salt marshes in the Mediterranean region, reproductive development is more sensitive to high soil salinity than vegetative growth. To investigate the possible role of calcium and magnesium salts in the responses of this species to salt stress, adult plants were submitted over a 2-month period to treatments with 300 mM NaCl-a concentration which affects, but does not completely inhibit seed formation in P. crassifolia-either alone or combined with low concentrations of CaCl2 (10 mM) or MgCl2 (20 mM). The NaCl treatment did not affect plant vegetative growth and had a stimulating effect on flowering. Yet almost half the spikes produced had aborted seeds, and the effect on seed number and quality-estimated by their mean weight and germination capacity-was obviously deleterious. Addition of calcium or magnesium chloride during the salt-stress treatment completely counteracted the negative effect of NaCl on the reproductive success of the plants: the number, weight and germination frequency of the seeds were similar to that in the control, non-stressed plants. These results indicate that both divalent cations can suppress or mitigate the deleterious effects of salt stress. While this protective role is well established in the case of calcium, we provide here the first experimental evidence of a similar function for magnesium.Work in the UPV laboratories was funded by a grant to O.V. from the Spanish Ministry of Science and Innovation (Project CGL2008-00438/BOS), with contribution from the European Regional Development Fund. M.-N.G. acknowledges the support provided by the Romanian POSDRU/89/1.5/S/49944 project ‘Developing the innovation capacity and improving the impact of research through post-doctoral programmes’, and by COST Action FA0901: ‘Putting Halophytes to work-From Genes to Ecosystems’ for his stay in Valencia in the frame of a Short Term Scientific Mission.Grigore, MN.; Boscaiu Neagu, MT.; Llinares Palacios, JV.; Vicente Meana, Ó. (2012). Mitigation of Salt Stress-Induced Inhibition of Plantago crassifolia Reproductive Development by Supplemental Calcium or Magnesium. NOTULAE BOTANICAE HORTI AGROBOTANICI. 40(2):58-66. https://doi.org/10.15835/nbha4028246586640

Anatomical Modifications in two Juncus Species under Salt Stress Conditions

[EN] The anatomic structure of roots and culms of two Juncus species with different degrees of salt tolerance was analysed in plants grown for two months under salt stress (NaCl treatments) and in control, non-treated plants. The aim of the study was not only to compare the anatomical structures of a halophyte (J. acutus) and a related glycophyte (J. articulatus), but mostly to assess whether salt stress induced anatomical modifications, by identifying differences between control and treated plants. Several slight differences have been indeed detected, in terms of endodermis type, development of aerenchyma and extent of sclerenchyma in perivascular sheaths. The role of Casparian endodermis was here discussed in relation to its complex implications in controlling salt influx at the root level that is an efficient mechanism involved in halophytes. Aerenchyma is a common feature found in marshy halophytes, allowing them to survive naturally under flooding conditions; however, when occurring in non-waterlogged plants, as is the case of this study, it should be regarded as a genetically, constitutive adaptation rather than an inducible one. Nevertheless, such anatomic modifications should be regarded as mere alterations due to stress that is, as stress responses and not as truly adaptations to salinity. In this context, the nature of these modifications either considered as adaptations or damage indicators of salt stress should be further reconsidered.Work in the UPV laboratories was funded by a grant to O.V. from the Spanish Ministry of Science and Innovation (Project CGL2008-00438/BOS), with contribution from the European Regional Development Fund. M.A.H. is a recipient of an Erasmus Mundus pre-doctoral scholarship financed by the European Commission (Welcome Consortium).Al Hassan, M.; Gohari, G.; Boscaiu Neagu, MT.; Vicente Meana, Ó.; Grigore, MN. (2015). Anatomical Modifications in two Juncus Species under Salt Stress Conditions. NOTULAE BOTANICAE HORTI AGROBOTANICI. 43(2):501-506. https://doi.org/10.15835/nbha43210108S50150643

Mitigation of Salt Stress-Induced Inhibition of Plantago crassifolia Reproductive Development by Supplemental Calcium or Magnesium

In Plantago crassifolia, a moderate halophyte characteristic of borders of salt marshes in the Mediterranean region, reproductivedevelopment is more sensitive to high soil salinity than vegetative growth. To investigate the possible role of calcium and magnesiumsalts in the responses of this species to salt stress, adult plants were submitted over a 2-month period to treatments with 300 mMNaCl-a concentration which affects, but does not completely inhibit seed formation in P. crassifolia-either alone or combined with lowconcentrations of CaCl2 (10 mM) or MgCl2 (20 mM). The NaCl treatment did not affect plant vegetative growth and had a stimulatingeffect on flowering. Yet almost half the spikes produced had aborted seeds, and the effect on seed number and quality-estimated bytheir mean weight and germination capacity-was obviously deleterious. Addition of calcium or magnesium chloride during the saltstresstreatment completely counteracted the negative effect of NaCl on the ‘reproductive success’ of the plants: the number, weightand germination frequency of the seeds were similar to that in the control, non-stressed plants. These results indicate that both divalentcations can suppress or mitigate the deleterious effects of salt stress. While this protective role is well established in the case of calcium,we provide here the first experimental evidence of a similar function for magnesium

Comparative studies on the stress responses of two Bupleurum (Apiaceae) species in support of conservation programmes

[EN] Bupleurum tenuissimum is a rare species in Spain, which became extinct in recent decades in many localities, including protected areas. In the study area, the ¿Albufera¿ Natural Park (SE Spain), the species was present in Limonietalia grasslands, a priority and endangered habitat, but has not been observed in the last 40 years. At present, it is included in conservation programmes aimed at its reintroduction in this territory. This study¿s primary objective was to establish the limits of tolerance of this species to salt and water stress under controlled greenhouse conditions. A congeneric species, B. fruticousm, was included as comparative material to get insights into its stress response mechanisms. Analysis of changes in growth parameters (stem length, number of leaves, root length, fresh weight and water content of roots and leaves) in response to the applied stress treatments confirmed that B. tenuissimum behaves as a facultative (moderate) halophyte susceptible to drought stress, whereas B. fruticosum is not severely affected by water stress but is sensitive to salinity, even at low NaCl concentrations. The stress-induced changes in several biochemical parameters (contents of photosynthetic pigments, ions, osmolytes, oxidative stress markers, and non-enzymatic antioxidant compounds, and specific activities of relevant antioxidant enzymes) explained the differential behaviour of the investigated Bupleurum species. In addition to the novelty of these findings in a genus that has rarely been studied from this perspective, these results will be relevant for implementing and managing B. tenuissimum conservation programmes, guiding the selection of reintroduction sites. The study also provides valuable information on the stress tolerance of B. fruticosum, with great potential for the ecological restoration of Mediterranean dry forest vegetation and riparian thickets.This research was partially funded by Project AICO/2017/039 from Generalitat Valenciana, granted to M. Boscaiu. The participation of M. Leandro has been supported by a mobility stay funded by the Erasmus+-KA1 Erasmus Mundus Joint Master Degrees Programme of the European Commission under the PLANT HEALTH ProjectGonzález-Orenga, S.; Leandro, MEDA.; Tortajada, L.; Grigore, MN.; Llorens Molina, JA.; Ferrer-Gallego, PP.; Laguna Lumbreras, E.... (2021). Comparative studies on the stress responses of two Bupleurum (Apiaceae) species in support of conservation programmes. Environmental and Experimental Botany. 191:1-15. https://doi.org/10.1016/j.envexpbot.2021.104616S11519