Anatomical Features of the Endengered Plant Cakile Maritima Scop

Annals of West University of Timişoara, ser. Biology, 2014, vol XVII (2), pp.79-86

ANATOMICAL FEATURES OF THE ENDENGERED PLANT CAKILE MARITIMA SCOP. SUBSP. EUXINA (POBED.) NYÁR.

Loreley Dana JIANU 1, Rodica BERCU 2, Răzvan Dan POPOVICIU 2

1Uniunea Practicienilor de Protecţia Mediului din Romania 2Faculty of Natural and Agricultural Sciences,”Ovidius” University, Constantza University Alley, No. 1, B, 900470, Constantza Corresponding author e-mail: [email protected] Received 29 July 2014; accepted 8 September 2014

ABSTRACT The paper presents anatomical featuress of the vegetative organs of an endengered plant Cakile maritima Scop.subsp. euxina (Pobed.) Nyár. The root has a secondary structure, due to the phelogen and cambium activity, The stem has a one-layered epidermis, covered by thick cuticle, a differentiated cortex and a large number of collateral vascular bundles in its upper part. The leaf lobes have a homogenous mesophyll and is amphistomatic. The mechanical tissue is represented by sclerenchymatous fibers in the root and collenchyma tissue in the stem. KEY WORDS: anatomy, root, stem, leaf, Cakile maritima, halophytes

INTRODUCTION Halophytes can grown in saline to extremely saline habitats and have particular characteristics which enable them to evade and/or tolerate salinity by various eco-physiological mechanisms. Anatomical features of different organs by halophytes are considered an adaptive response to habitat ecology of a certain species (Chrispeels & Sadava, 2003; Grigore & Toma, 2007; Ianovici, 2011a; Ianovici, 2011b; Ianovici et al , 2010). Cakile maritima is an annual succulent halophyte widely distributed in sandy coasts throughout the world (Clausing et al , 2000). This species is found in beach dunes below 50m and is native to Europe. This plant is naturally salt-tolerant plant that displays potential for economical (oilseed), nutrient food and chemotherapeutic utilization (Ksouri et al. 2007). The high lipid content of seeds may be useful for biofuels production (Ciccarelli et al , 2010). Much of the ecological information has resulted from interest in the observed ecological replacement of Cakile edentula with Cakile maritima on the western coasts of North America and Australia (Boyd & Barbour, 1993). The effects of habitat and predation on the population biology of Cakile maritima on the west coast of North America have been investigated by Boyd (1991). Maun and Payne (1989) investigated the adaptive significance of fruit and seed dimorphism. Pakeman and Lee (1991a, 1991b) evaluated environmental factors 79

JIANU et al: Anatomical features of the endengered plant Cakile maritima Scop.subsp. euxina (Pobed.) Nyár. contributing to differences in the performance of Cakile maritima in strandline and foredune habitats. These authors found a marked difference in growth dependent upon their position of establishment. The authors conclude that nitrogen differences account for the observed growth differences, probably by controlling photosynthetic rates. In Europe, Cakile maritima is divisible into at least four subspecies: ssp. integrifolia (Hornem.) Hyl. ex Greuter & Burdet (= ssp. maritima ), ssp. baltica (Jordan ex Rouy & Fouc.) Hylander ex P.W. Ball, ssp. aegyptiaca (Willd.) Nyman and ssp. euxina (Pobed.) E.I. Nyárády (Ciccarelli et al , 2010). In Romania, on the sea shore and sand dunes (with coarser sands), Cakile maritima Scop.subsp. euxina (Pobed.) Nyár (commonly known as sea rocket) is rare. About its sozological status, Cakile maritima subsp. euxina is considered to be endengered (EN) (Dihoru & Negrean, 2009), mainly due to human impact (constructions, rehabilitation and arrangements for tourism of the beaches) in Constanta and Mamaia Nord and even Navodari populations of this plant can be considered as extinct. Populations of this species are in real restriction despite the chorological data which indicate the presence of this species from the North to South of the sea shore, in both counties Tulcea and Constanta: Sulina, Sf. Gheorghe, Jurilofca,

FIG. 1. Natural view of Cakile maritima Sandbank Chituc, Sandbank Saele- Histria Scop. subsp. euxina (Pobed.) Nyár. Ancient City, Sinoe Lake, Cape Midia, Agigea, between Eforie Nord si Sud, Eforie Sud, Tuzla, Costinesti, Vama Veche, Northern Mangalia (Oprea, 2005; Dihoru & Negrean, 2009). It has an erect or decumbent many-branched stem and fleshy glabrous 1-2 pinatisected glabrous leaves. Flowers are typically pale mauve to white, with petals about 1 cm in length. Few data are known about this species anatomy. Most of the studies refer to the some morpho-functional leaf adaption to its saline environment. Ball (1984) and Davy et al . (2006) reported that there is a morphological cline from types with entire leaves in the north of Europe, to types with pinnatifid leaves in the south and east of Europe. Other authors refer to the salinity effects on polyphenol content and antioxidant activities (Kasouri et al, 2007). Some data suggest that the capacity to limit oxidative damage is important for salt tolerance of C. maritima (Amor et al , 2006). C. maritima seeds can survive up to 4 months immersion in sea water and up to 1 year of floating in sea water (Gandour et al , 2008). In the Romanian literature data on this

Annals of West University of Timişoara, ser. Biology, 2014, vol XVII (2), pp.79-86 species structure almost lack. Few references are made in their study on halophytic plants by Grigore and Toma (2010), without being studied in particular. The purpose of this paper is to highlight some anatomical features of Cakile maritima subsp. euxina vegetative organs and to contribute with more information to the knowledge concerning this endangered species.

MATERIAL AND METHOD The plant was collected from Vama Veche - 2 Mai sandy sea shore (Constantza County) in may 2014. Pieces of root, stem and leaf were fixed in FAA (formalin: glacial acetic acid: alcohol 5:5:90). Cross sections of the vegetative organs were performed by the free hand made technique (Bercu & Jianu, 2003; Ianovici, 2006). The samples were stained with alaun-carmine and iodine green. Anatomical observations and micrographs were performed with a BIOROM–T bright field microscope, equipped with a TOPICA 6001A video camera.

RESULTS AND DISCUSSIONS The root. The phellogen (cork cambium) produces 5-6 layers of suberized cells to the exterior - the cork – and 2-4 layers of phelloderm, inside, forming the periderm. The cortex deposse numerous starch grains. In the cortex floem fibers are present, surrounding the root, its continuity being interrupted by the pith rays (Fig. 2, Fig 3).

FIG. 2. Cross section of the root - ensemble: pd- phellorderm, ph- phloem, pi- pith, scl- sclerenchyma, x- xylem.

JIANU et al: Anatomical features of the endengered plant Cakile maritima Scop.subsp. euxina (Pobed.) Nyár.

FIG.3. Cross section of the root. Portion with cork and cortex: c- cortex, ck- cork, pd- phellorderm, ph- phloem, pi- pith, scl- sclerenchyma, x- xylem.

Cambium produces a thin liner of secondary phloem consisting of phloem vessels, companion cells, phloem parenchyma. Inward, cambium generates a secondary thick xylem mass, composed of xylem vessels, those of the peripheral zone, in a reduce number, are placed in a cellulosic parenchyma and into a sclerenchymatose one, in rest (Fig. 2; Fig. 4, A). Some primary elements are present to the pith zone. Radial cellulosic pith rays are present, connecting the pith with cortex. The pith consists of parenchyma cells, with intercellular spaces (Fig. 4, B). The stem. Cross section of the upper part of the stem discloses in the superior part a sinuous circular shape (Fig. 3, A). However, to the exterior the unistratous epidermis is represented by rounded shaped cells, covered by a relatively thck cuticle. Here and there sunken stomata are present. Bellow the epidermis is the cortex. The external cortex (1 or 2 layers of cells) - hipodermis – is slightly colenchymatous cellsand possesschloroplasts. The rest are parenchymatous in nature. Endodermis consists of starch grains - an amilipherous sheath. It is less distinct and may be recognized by its orderly cells row (Fig. 3, A: Fig. 4, A). The vascular system is represented by 24-25 vascular open and collateral bundles separated by sclerified pith rays. Some sclerified elements are present at the periphery.An interfascicular cambium is present only, because those interfascicular one operated unequally being exhaust itself especially in floem elements. Xylem is formed by xylem vessels, arranged in a cellulosic parenchyma (Fig. 4). The central part of the stem is occupied by the pith, composed of large parenchymatous cells with intercellular spaces (Fig. 3, A).

Annals of West University of Timişoara, ser. Biology, 2014, vol XVII (2), pp.79-86

A B FIG. 2.Cross sections of the root. Portion of the vascular systrm (A) and pith (B): cb- cambium, cp-cellulosic parencyma, ph- phloem, sclp- sclerenchymatous parenchyma, xv- xylem vessel.

A B FIG. 3. Cross section of the stem. Ensemble (A). Portion with epidermis and cortex (B): c- cortex, cu- cuticle, e- epidermis, pi- pith, vb- vascular bundle.

JIANU et al: Anatomical features of the endengered plant Cakile maritima Scop.subsp. euxina (Pobed.) Nyár.

The leaf. The cauline leaf lobe, in cross section, has a convex shape to the adaxial surface anda concave one, to the abaxial surface with two large lobes. Both epidermises are single-layered and covered by cuticle. The mesophyll is homogenous but the first 2-3 layers of cells are chlorenchymatous, this tissue being more developed abadxial and in the lateral lobes (Fig. 5, A). Such as Ciccarelli et al. (2010), reported, slightly above stomata are present, on both sides to permit high rates of carbon dioxide uptake. This fact could be interpreted as an adaptation to sand burial, which is a frequent event in maritime sand dune ecosystems (Ciccarelli et al ., 2009). In the basic parenchyma are 5-7 collateral vascular bundles, such as those in the stem, one larger in abaxială position and the other small in lateral and adaxial possition (Fig. 5, A). The FIG. 4. A stele vascular bundle of the difference consists of the fact that xylem vessels upper part of the stem in cross section: are obviously in a radial arrangement, being more cb-- cambium, ph- phloem, xv- xylem vessel. developed than the floem and the bundle sheath is likely collenchymatous (Fig. 5, B).

A B FIG. 5. Cross section ofaleaf lobe.Ensemble (A). A large vascular bundle of the mid rib (B): cobs- collencyma bundle sheath, ph- phloem, x- xylem.

Annals of West University of Timişoara, ser. Biology, 2014, vol XVII (2), pp.79-86

CONCLUSIONS • The root has a secondary structure with a well developed xylem tissues and a more or less poor developed phloem. Air spaces are present. • The stem possesses a slightly differentiated cortexrepresented by collenchyma and the rest of the cortex is parenchymatous in nature. An amilipherous sheath is present as well.The vascular system is represented by numerous vascular collateral bundles separated by sclerified pith rays. • The blade ishomogenousand amphistomatic with 5-7 vascular bundles. • The mechanical tissue in the root is represented by fibers and in the stem and leaf by a collenchyma tissue. • The root has a secondary structure with a well developed xylem tissues and a more or less poor developed phloem. Air spaces are present. • The stem possesses a slightly differentiated cortexrepresented by collenchyma and the rest of the cortex is parenchymatous in nature.An amilipherous sheath is present as well.The vascular system is represented by numerous vascular collateral bundles separated by sclerified pith rays. • The blade ishomogenousand amphistomatic with 5-7 vascular bundles. • The mechanical tissue in the root is represented by fibers and in the stem and leaf by a collenchyma tissue.

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JIANU et al: Anatomical features of the endengered plant Cakile maritima Scop.subsp. euxina (Pobed.) Nyár.

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