Metaxylem Area Research Articles

Drought effects on trait space of winter wheat are independent of land management.

Investigating plant responses to climate change is key to develop suitable adaptation strategies. However, whether changes in land management can alleviate increasing drought threats to crops in the future is still unclear. We conducted a management × drought experiment with winter wheat (Triticum aestivum L.) to study plant water and vegetative traits in response to drought and management (conventional vs organic farming, with intensive vs conservation tillage). Water traits (root water uptake pattern, stem metaxylem area, leaf water potential, stomatal conductance) and vegetative traits (plant height, leaf area, leaf Chl content) were considered simultaneously tocharacterise the variability of multiple traits in a trait space, using principal component analysis. Management could not alleviate the drought impacts on plant water traits as it mainly affected vegetative traits, with yields ultimately being affected by both management and drought. Trait spaces were clearly separated between organic and conventional management as well as between drought and control conditions. Moreover, changes in trait space triggered by management and drought were independent from each other. Neither organic management nor conservation tillage eased drought impacts on winter wheat. Thus, our study raised concerns about the effectiveness of these management options as adaptation strategies to climate change.

Invasive success of star weed (Parthenium hysterophorus L.) through alteration in structural and functional peculiarities.

Parthenium weed poses significant threats to cropping systems, socioeconomic structures, and native ecosystems. The pronounced impact is primarily attributed to its rapid and efficient invasion mechanism. Despite that the detrimental effects of Parthenium weed are widely acknowledged, an in-depth scientific comprehension of its invasion mechanism, particularly regarding modifications in structural and functional attributes under natural conditions, is still lacking. To bridge this knowledge gap and formulate effective strategies for alleviating the adverse consequences of Parthenium weed, a study was conducted in the more cultivated and densely populated areas of Punjab, Pakistan. This study was focused on fifteen distinct populations of the star weed (Parthenium hysterophorus L.) to investigate the factors contributing to its widespread distribution in diverse environmental conditions. The results revealed significant variations in growth performance, physiological traits, and internal structures among populations from different habitats. The populations from wastelands exhibited superior growth, with higher accumulation of soluble proteins (TSP) and chlorophyll content (Chl a&b, TChl, Car, and Chl a/b). These populations displayed increased root and stem area, storage parenchyma, vascular bundle area, metaxylem area, and phloem area. Significant leaf modifications included thicker leaves, sclarification around vascular bundles, and widened metaxylem vessels. Roadside populations possessed larger leaf area, enhanced antioxidant activity, increased thickness of leaves in terms of midrib and lamina, and a higher cortical proportion. Populations found in agricultural fields depicted enhanced shoot biomass production, higher levels of chlorophyll b, and an increased total chlorophyll/carotenoid ratio. Additionally, they exhibited increased phloem area in their roots, stems, and leaves, with a thick epidermis only in the stem. All these outcomes of the study revealed explicit structural and functional modifications among P. hysterophorus populations collected from different habitats. These variations were attributed to the environmental variability and could contribute to the widespread distribution of this species. Notably, these findings hold practical significance for agronomists and ecologists, offering valuable insights for the future management of Parthenium weed in novel environments and contributing to the stability of ecosystems.

Survival tactics of an endangered species Withania coagulans (Stocks) Dunal to arid environments.

Withania coagulans is a valuable medicinal plant with high demand, but its wild growth and local usage pose a threat to its natural habitat. This study aims to understand the plant's growth, anatomy, and physiology in different environmental conditions to aid in conservation and re-vegetation efforts. Fifteen differently adapted populations of Withania coagulans were collected from diverse ecological regions, viz., (i) along the roadside, (ii) hilly areas, (iii) barren land, and (iv) wasteland to unravel the adaptive mechanisms that are responsible for their ecological success across heterogenic environments of Punjab, Pakistan. The roadside populations had high values of photosynthetic pigments, total soluble proteins, root endodermis thickness, stem and leaf cortical thickness, and its cell area. The populations growing in hilly areas showed better growth performance such as vigorous growth and biomass production. Additionally, there was enhanced accumulation of organic osmolytes (glycine betaine and proline), chlorophyll content (chl a/b), and enlarged epidermal cells, cortical cells, vascular bundles, metaxylem vessels, and phloem region in roots. In case of stem area, epidermal thickness, cortical thickness, vascular bundle, and pith area showed improved growth. However, the barren land population showed significant increase in carotenoid contents, vascular bundle area, and metaxylem area in roots, and xylem vessels and phloem area in stems and leaves. The wasteland population surpassed the rest of the populations in having greater root dry weight, higher shoot ionic contents, increased root area, thick cortical, and vascular bundle area in roots. Likewise, cortical thickness and its cell area, and pith area in stems, whereas large vascular bundles, phloem region, and high stomatal density were recorded in leaves. Subsequently, natural populations showed the utmost behavior related to tissue organization and physiology in response to varied environmental conditions that would increase the distribution and survival of species.

Morphological and Structural Responses of Albizia lebbeck to Different Lead and Nickel Stress Levels

Lead (Pb) and nickel (Ni) are serious soil pollutants that adversely affect plant growth and development and need to be removed through phytoremediation. The present study aimed to assess the morphological indices of Albizia lebbeck (L.) (Benth.) in relation to anatomical modifications for survival under both Pb and Ni stress. The seedlings of A. lebbeck were established and then subjected to four different concentrations, viz. 0 mM, 25 mM, 50 mM and 75 mM, of Pb and Ni for 14 days in two phases. Morphological traits such as shoot length (70.93%), fresh weight (79.27%), dry weight (83.9%), number of root hairs (65.7%), number of leaves per plant (67.4%) and number of leaflets per plant greatly reduced under Pb or Ni stress. Surprisingly, root length increased rather than decreased with the increase in Pb or Ni concentrations, along with an increase in leaflet width, leaflet length and leaflet area. Moreover, root cortical cell area, metaxylem area and phloem area decreased at 75 mM of Pb and Ni while epidermal thickness and cell area increased. Stem epidermal thickness, cell area and phloem area significantly decreased with the consistent increase in metaxylem area and cortical region thickness under both Pb and Ni stress. Leaf anatomical traits such as midrib thickness, abaxial epidermal thickness and stomatal density and adaxial epidermal thickness and stomatal area significantly increased with increasing Pb or Ni stress. Correlation analysis revealed close relations among morphological and anatomical traits (such as root length with cortical region thickness) for better plant survival under Pb or Ni stress, and a PCA-biplot further verified these correlation analyses. Cluster analyses demonstrated the associations among the morphological and anatomical traits based on different stress levels. Furthermore, we found that the longer exposure (from phase 1 to phase 2) of heavy metals stress is more dangerous for plant survival and can ultimately lead to plant death. Moreover, our results also confirmed that Ni is more harmful or dangerous to plants than Pb at high and moderate concentrations. The anatomical modifications ensured the survival of A. lebbeck in extreme heavy metals stress and therefore unlocked its potential to be used as a natural source of phytoremediation. We also recommend that the genetic potential of A. lebbeck associated with its survival under heavy metal stress be investigated.

Phytoremediation potential modulated by structural and functional traits in a saline desert halophyte Fagonia indica Burm. f.

Using halophytes for phytoremediation is an environmentally friendly technique, now gaining importance all over the world. Fagonia indica Burm. f. (Indian Fagonia) is primarily distributed in salt-affected lands of the Cholistan Desert and surrounding habitats. Four populations with three replications from salt-affected habitats were collected from natural habitats to evaluate structural and functional adaptation for salinity tolerance and phytoremediation of hypersaline habitats. The populations collected from the highest saline sites Pati Sir (PS) and Ladam Sir (LS) had restricted growth habit, increased accumulation of K+ and Ca2+ along Na+ and Cl-, more excretion of Na+ and Cl-, increased cross-sectional area of root and stem, larger exodermal and endodermal cells in roots, and broad metaxylem area. Sclerification in stem was high in population. Specific modifications in leaves were reduced stomatal area and increased adaxial epidermal cell area. Important traits associated with phytoremediation potential of F. indica populations (Pati Sir and Ladam Sir) were deeper roots and taller plants, increased density of salt glands on leaf surface, and high excretion of Na+. Additionally, higher bio-concentration factor, translocation factor, and dilution factor for Na and Cl- in same Ladam Sir and Pati Sir population were identified as key phytoremediation attributes. The plants of F. indica colonizing high salinities (Pati Sir and Ladam Sir) were, therefore, more efficient in phytoremediation of saline soils as these populations accumulated and/or excrete toxic salts. Density of salt glands remarkably increased in the Pati Sir population collected from the highest salinity. This population accumulated and excreted the highest amount of Na+ and Cl-. The dilution factor of Na+ and Cl- ions was also the highest in this population. Anatomical modifications such as root and stem cross-sectional areas, proportion of storage parenchyma, and broad metaxylem vessels were the maximum in Pati Sir population. These modifications indicate not only better salt tolerance of the Pati Sir population but also better in accumulation and excretion of toxic salts. This population can potentially rehabilitate hypersaline uncultivated lands through green reclamation.

Plant height shapes hydraulic architecture but does not predict metaxylem area under drought in Sorghum bicolor.

Climate change-induced variations in temperature and precipitation negatively impact plant growth and development. To ensure future food quality and availability, a critical need exists to identify morphological and physiological responses that confer drought tolerance in agro-economically important crop plants throughout all growth stages. In this study, two Sorghum bicolor accessions that differ in their pre-flowering responses to drought were exposed to repeated cycles of drying and rewatering. Morphological, physiological, and histological traits were measured across both juvenile and adult developmental stages. Our results demonstrate that plant height is not predictive of metaxylem area but does influence the hydraulic path and water management in an accession-specific manner. Further, when drought-responsive changes to the plant architecture are unable to compensate for the hydraulic risk associated with prolonged drought exposure, tight control of stomatal aperture is crucial to further mitigate hydraulic damage and prevent xylem embolism.

Genetic analysis of root vascular traits in a population from two temperate japonica rice ecotypes

ABSTRACT The genetic basis for root vascular traits in rice, despite its direct impacts on root axial and radial hydraulic conductivity, has not been widely studied compared with deep rooting traits. We used five phenotyping datasets (i.e. from maturity stage grown in upland field in 2013, and from vegetative and maturity stages grown in upland and lowland fields in 2019) to quantify the genotypic variations and genomic regions of root vascular traits in a temperate japonica mapping population (from lowland Otomemochi (OTM) and upland Yumenohatamochi (YHM)). YHM had larger stele transversal area (STA) and total late metaxylem area (LMXA), as well as higher deep root ratio and total root length at deeper layers (>30 cm) than OTM. Root vascular traits were significantly different among progenies in each dataset, and the size of genotype-by-environment interactions was comparable. Root vascular traits were not positively correlated with deep rooting traits. From the multi-environment analysis of all five datasets, four key genomic regions related to STA in both joint and separate analyses were detected on chromosome 2 (RM3703-RM6379, RM6933-RM3857), chromosome 4 (RM1388-RM5503) and chromosome 12 (RM247-RM155), with the first and third collocated with deep rooting traits. QTL-by-environment interaction was comparable to the main additive effect. This study is the first report on genomic regions of root vascular traits in a japonica mapping population.

Structural responses of differentially adapted Cenchrus setigerus Vahl ecotypes to water deficit

Two ecotypes of Cenchrus setigerus Vahl (birdwood grass) were collected from dry mountains surrounding hyper-saline Kalar Kahar Lake and Gatwala artificial forest plantation. The ramets of the two ecotypes were established in pots for 15 days and then subjected to 100% FC (control) or 75% and 50% FC (field capacity) levels. Growth attributes such as plant height, tillers per plant, leaves per plant, shoot fresh and dry weights were severely affected while root length was the only attribute that increased in both ecotypes under moisture stress. Root anatomical attributes like cortical and pith parenchyma, and vascular region thickness increased in both ecotypes under water stress. Root radius increased in the Faisalabad ecotype at 75% FC, while increased in Salt Range ecotype only at 50% FC. Stem cellular region, sclerenchymatous cell area, vascular bundle area and metaxylem area increased significantly under moderate and severe water deficit only in the Faisalabad ecotype. The Salt Range ecotype exhibited intensive sclerification and large vascular tissue at 50% FC. Leaf anatomical attributes like epidermal cell area, bundle sheath thickness, sclerenchyma thickness and its cell area, and, vascular bundles area significantly increased in the Salt Range ecotype with increasing water deficit. The Faisalabad ecotype showed significant increase in vascular bundle area, metaxylem area and adaxial stomatal area. These findings indicated that both C. setigerus ecotypes mainly relied on water conservation and survival rather than maintaining growth and biomass production. The anatomical modifications at root, stem and leaf levels ensured survival of C. setigerus ecotypes in extreme arid conditions. • Growth attributes were severely affected while root length increased under stress • Root radius increased in the Faisalabad ecotype at 75% FC, while at 50% FC in Salt Range ecotype • Stem area, sclerification and vascular bundle area increased only in Faisalabad ecotype • The Salt Range ecotype exhibited intensive sclerification in leaves and large vascular tissue at 50% FC • The Faisalabad ecotype showed an increase in vascular bundle area, metaxylem area and adaxial stomatal area

Morpho-anatomical, biochemical and molecular genetic responses of canola (Brassica napus L.) to sulphur application

Brassica napus (canola), a major economic crop in Egypt, contains much oils and proteins. In the present study, the foliar applications of ammonium sulphate (A.S.) [(NH4)2SO4] (0, 1% 0.2% and 0.3%) to canola plants had distinctive impacts on the morpho-anatomical, biochemical, and molecular genetic responses. Interestingly, there is a positive impact when sulphur (S) is foliarly applied at 0.2% of A.S. as revealed in antioxidants, flavonoids, total carbohydrates, and protein contents which were significantly affected. On the other hand, higher levels of glucosinolates were recorded for 0.3% and 1% A.S. (4.838 and 1.905, respectively). The electrophoretic analysis of proteins displayed 51 bands of molecular weights ranging from 8.555 to 240.6 kDa with 88.24% polymorphism with a mean band frequency of 0.373. Cytotoxicity assay revealed that the lower cell death was detected in treated root tips of canola plants following 0.2% A.S. treatment, as compared to control. With increasing of sulphur treatment, the root cortex thickness, number of conducting elements, and pericycle thickness decreased while root pith area increased. In canola leaves of high S level, the leaf blade thickness, the thickness of abaxial and adaxial epidermis surface, mesophyll thickness, and metaxylem area increased, while the xylem conducting elements number decreased. Moreover, SCoT molecular markers have been used to evaluate the genetic variation among Brassica napus genotypes subjected to different A.S. treatments. Four of the seven SCoT primers were revealed to be polymorphic in both treated and untreated samples. A total of 39 amplicons, ranging in size from 200 to 1080 bp, were amplified, with 9 (23.07%) of them being polymorphic. Clustering dendogram based on SCot markers data divided Brassica genotypes into two main clusters based on similarity coefficients indices. B. napus treated with 0.2% A.S. was separated in a distinct cluster. Furthermore, treatments with sulphur enhanced the activity of antioxidant enzymes as well as the expression level of their encoding genes (CAT, catalase; POD, peroxidase; APX, ascorbate peroxidase; SOD, superoxide dismutase; GR, glutathione reductase), particularly at 1% and 0.2% A.S. treatments. Taken together, this study revealed that foliar application of sulphur treatments, particularly at 0.2%, have a great potential to improve canola crop.

Contribution of structural and functional modifications to wide distribution of Bermuda grass Cynodon dactylon (L) Pers.

Fifteen ecologically distinct ecotypes of Bermuda grass Cynodon dactylon (L.) Pers. were evaluated for key factors involved in its widespread distribution in different environmental conditions. Ecotypes collected from saltmarshes showed better vegetative growth, accumulation of inorganic ions (Na+, K+ and Ca2+), compatible solutes (proline and glycine betaine) and higher activities of antioxidative enzymes (superoxide dismutase, catalase and peroxidase) than all other ecotypes. Increased root and stem radii, sclerification intensity, aerenchyma formation, storage parenchyma (pith and cortex), vascular bundle area and metaxylem area were also observed in the same ecotypes. Notable leaf modifications included development of thicker leaves with intensive sclerification around vascular bundles and wide metaxylem vessels. Ecotypes collected from saline dryland featured large leaf area, increased level of glycine betaine, intensive sclerification and wide leaf xylem vessels. Ecotypes from deserts/semi-deserts exhibited higher soluble proteins and carotenoids, thick epidermis of stem and leaf blade, large cortex and broad metaxylem vessels in root, thick leaf sheaths, well-developed bulliform cells and stomata more oriented towards abaxial surface. Ecotypes collected from river or canal bank possessed high chlorophyll content (chl a, chl b and total chl), epidermal and storage parenchyma cell size, endodermal thickness in root, metaxylem area in stem, sclerification in leaf sheath and increased stomatal density on adaxial leaf surface. In conclusion, ecotypes collected from different habitats exhibited explicit variation in structures (internal modifications) and functions (physiology) due to environmental variability that may contribute to the wide distribution of C. dactylon.

Adaptive traits for drought tolerance in red-grained wheat (Triticum aestivum L.) landraces

Forty-nine accessions were collected from arid and semi-arid areas of Pakistan to explore adaptive components in red-grained wheat (Triticum aestivum L.). Single-line selections of these accessions were grown on an arid and a control site; that is, Uchkera Farm (UF) and Botanical Garden (BG), Faisalabad. The accessions grown at BG exhibited significantly better biomass and grain yield production than those grown at UF. Accession Ck5 from Chakwal produced the maximum grain yield (17.7 g plant−1) at BG and Jm3 (8.1 g plant−1) at UF. Among the eight accessions selected for further anatomical studies, Dg2 showed increased yield per plant at UF, which was related to root modifications like increased cortical region thickness, endodermal cell area, vascular region thickness, metaxylem area, and root hair length. Stem modifications included increased vascular bundle area, phloem area and stomatal density, while leaves showed increased cuticle thickness, bulliform cell thickness, trichome density, and length. Increased stomatal density and area were also found. Accession Jm3 showed a decrease in yield at UF. Root modifications in Jm3 included increased epidermal cell area, sclerenchymatous thickness, endodermal cell area, and root hair length. Stem modifications in this accession included increased stem cellular region thickness and sclerenchymatous cell area. Leaves had increased abaxial epidermal cell area, trichome number and length, and abaxial stomatal density. In conclusion, morpho-anatomical characteristics varied greatly in the red-grained wheat accessions at both experimental sites that have potential for incorporation into breeding efforts for drought tolerance in modern wheat cultivars.

Fungal endophyte Epichloë bromicola infection regulates anatomical changes to account for salt stress tolerance in wild barley (Hordeum brevisubulatum)

Plants can minimize the adverse effects of salinity by modifying morphological and anatomical features. Previous studies showed that endophytic Epichloe bromicola play an important role in improving wild barley (Hordeum brevisubulatum) salinity tolerance. The aim of this work is to understand whether Epichloe endophyte affects the anatomical structures of host H. brevisubulatum under salinity environments. Seedlings of E. bromicola infected (E+) and E. bromicola free (E-) H. brevisubulatum were treated with different NaCl concentrations, with the control seedlings being grown without NaCl. Anatomical structures of roots, stems and leaves were observed by making paraffin sections with double staining dehydration methods (safranin and fast green). NaCl treatments significantly affected the anatomical structure of H. brevisubulatum. Vascular tissue area throughout the leaf, stem and root decreased as the NaCl concentration increased. Thickness of epidermis in stems and leaves, and the cortex in roots also decreased with salt level increases. Endodermis thickness, epidermis thickness and stele area in roots were increased under salinity stress. The presence of Epichloe endophyte regulated some anatomical structure modifications. Epichloe infection was associated with significant higher conducting tissues (including leaf xylem, leaf phloem, stem vascular bundles, stem xylem vessels and root meta-xylem area). The increased thickness of leaf veins, epidermis in stems, cortex and endodermis in roots were also associated with Epichloe endophyte infection under NaCl stress. The presence of Epichloe endophyte ameliorated adverse effects of salinity on H. brevisubulatum. We observed specific changes of anatomical structures that may help in inhibiting water loss and inhibiting decrease of transport capacity for better conduction of water, nutrients, photosynthates and re-translocation of assimilates to suppress negative effects of salinity and enhance the tolerance of H. brevisubulatum to salt stress.

Seminal and Nodal Roots of Barley Differ in Anatomy, Proteome and Nitrate Uptake Capacity.

The root system of barley plants is composed of embryogenic, seminal roots as well as lateral and nodal roots that are formed postembryonically from seminal roots and from the basal part of shoots, respectively. Due to their distinct developmental origin, seminal and nodal roots may differ in function during plant development; however, a clear comparison between these two root types has not yet been undertaken. In this study, anatomical, proteomic and physiological traits were compared between seminal and nodal roots of similar developmental stages. Nodal roots have larger diameter, larger metaxylem area and a larger number of metaxylem vessels than seminal roots. Proteome profiling uncovered a set of root-type-specific proteins, including proteins related to the cell wall and cytoskeleton organization, which could potentially be implicated with differential metaxylem development. We also found that nodal roots have higher levels of auxin, which is known to trigger metaxylem development. At millimolar nitrate supply, nodal roots had approximately 2-fold higher nitrate uptake and root-to-shoot translocation capacities than seminal roots, whereas no differences were found at micromolar nitrate supply. Since these marked differences were not reflected by the transcript levels of low-affinity nitrate transporter genes, we hypothesize that the larger metaxylem volume of nodal roots enhances predominantly the low-affinity uptake and translocation capacities of nutrients that are transported with the bulk flow of water, like nitrate.

Eco-physiological evaluation of Stele Transversal Area 1 for rice root anatomy and shoot growth

ABSTRACTLarger stele size with greater xylem area or endodermis thickness in rice roots may lead to higher plant water status and maintain yield. Sta1-NIL, a near-isogenic line of IR64 introgressed with Stele Transversal Area 1 (Sta1), a quantitative trait locus controlling stele transversal area (STA) was investigated together with IR64 for their root anatomy and physiological parameters, at seedling, heading and maturity stages in greenhouse and fields of water deficit and well-watered conditions in 2017 and 2018. Combined analysis of STA from nine observations of overall four experiments showed that STA was increased by 7% (35,400 to 37,800 μm2) by the introduction of Sta1 into IR64. Total late metaxylem area also increased by 6% (5,840 to 6,180 μm2), which came mainly from its single area rather than its number, whereas small increase in endodermis thickness was also noted. Genotype x observation for STA was marginal, but Sta1-NIL had larger STA under water deficit environments. Sta1-NIL also maintained higher mid-day leaf water potential (−2.34 ± 0.3 MPa) than IR64 (−2.57 ± 0.3 MPa). Meta-analysis of seven experiments under 14 environments showed tendency of the positive effect of Sta1 on grain yield increment (579 to 604 g m−2), which came from the increment of harvest index. This study indicated the importance of wider stele size for maintenance of higher plant water status and yield across different water regimes.

Structural modifications for drought tolerance in stem and leaves of Cenchrus ciliaris L. ecotypes from the Cholistan Desert

Cenchrus ciliaris L. is a perennial palatable grass and is capable of growing in a variety of habitats including extreme desert environment. The present study was conducted to explore the effect of drought stress on morpho-anatomical modifications in the aerial parts of C. ciliaris ecotypes, which were collected from the Cholistan Desert. Seeds of C. ciliaris wre collected from different regions in the Cholistan desert and grown in the Faisalabad conditions. Stress treatment were applied to the ramets that were isolated from mother plants. Three moisture regimes were maintained during the experiment, i.e., 100%, 75% and 50% field capacity. Ecotypes were grouped into four categories i.e., highly tolerant, tolerant, moderately tolerant and sensitive. Highly tolerant ecotypes (E92001 and E92002) showed epidermal thickness in leaves and stem, intensive sclerification in stem, increased vascular bundle number, well developed bulliform, increased metaxylem area and decreased stomatal density on both leaf surfaces. Tolerant ecotypes (E92003 an E92008) showed dense pubescence on their leaves. It is concluded that no definite or precise single character can be taken as a yardstick for adjudging the biomass production in theses desert grass ecotypes.

Exogenously applied proline induced changes in key anatomical features and physio-biochemical attributes in water stressed oat (Avena sativa L.) plants.

Oat (Avena sativa) plants grown under 60% field capacity (water-deficit stress) were subjected to proline (40mM) applied as a foliage spray. Water-deficit conditions suppressed plant growth, chlorophyll contents, leaf vascular bundle area, leaf phloem area and leaf midrib thickness, root diameter, root cortex thickness, stem diameter, stem vascular bundle area and stem phloem area. In contrast, water stress caused an increase in leaf proline, hydrogen peroxide, activities of peroxidase and superoxide dismutase enzymes, leaf bulliform cell area, leaf adaxial epidermis thickness, leaf sclerenchyma thickness, root metaxylem area, root epidermis and endodermis area, root stelar diameter, stem sclerenchyma thickness and stem epidermis thickness. However, exogenous application of proline significantly improved the plant growth, leaf proline contents, metaxylem area, mesophyll thickness, root diameter, root cortex thickness, root epidermis, endodermis thickness, stelar diameter, metaxylem area, stem diameter, stem vascular bundle area, stem epidermis area, stem phloem area and stem sclerenchyma thickness. Overall, foliar spray of proline was effective in improving drought stress tolerance which can be attributed to proline-induced significant modulations in physio-biochemical and anatomical features of oat plants.

Exogenously applied glycinebetaine induced alteration in some key physio-biochemical attributes and plant anatomical features in water stressed oat (Avena sativa L.) plants

Although exogenous application of glycinebetaine (GB) is widely reported to regulate a myriad of physio-biochemical attributes in plants under stressful environments including drought stress, there is little information available in the literature on how and up to what extent GB can induce changes in anatomical features in water starved plants. Thus, the present research work was conducted to assess the GB-induced changes in growth, physio-biochemical, and anatomical characteristics in two cultivars (CK-1 and F-411) of oat (Avena sativa L.) under limited water supply. After exposure to water stress, a considerable reduction was observed in plant growth in terms of lengths and weights of shoot and roots, leaf mesophyll thickness, leaf midrib thickness, root cortex thickness, root diameter, stem diameter, stem phloem area, and stem vascular bundle area in both oat cultivars. However, water stress resulted in a significant increase in leaf total phenolics, hydrogen peroxide (H2O2), ascorbic acid (AsA), GB contents, activities of enzymes (CAT, SOD and POD), total soluble proteins, leaf epidermis (abaxial and adaxial) thickness, bulliform cell area, sclerenchyma thickness, root endodermis and epidermis thickness, root metaxylem area, stem metaxylem area and stem sclerenchyma thickness in both oat cultivars. Foliar-applied 100 mM GB suppressed H2O2 contents, while improved growth attributes, free proline and GB contents, activity of SOD enzyme, leaf abaxial epidermis thickness, leaf bulliform cell area, leaf midrib thickness, leaf sclerenchyma thickness, root cortex thickness, root endodermis, epidermis thickness, root stele diameter, stem diameter, stem epidermis thickness, stem metaxylem area, and stem phloem and vascular bundle area in both oat cultivars. For both oat cultivars, CK-1 was superior to F-411 in leaf abaxial epidermis thickness, leaf mesophyll, leaf sclerenchyma, root metaxylem area, stem diameter, stem epidermis, sclerenchyma thickness, stem metaxylem area, and stem vascular bundle area. Overall, both oat cultivars showed inconsistent behavior to water stress and foliar-applied GB in terms of different physio-biochemical attributes, however, CK-1 was superior to F-411 in a number of anatomical features of leaf, root, and stem.

NaCl – Changes stem morphology, anatomy and phloem structure in Lucerne (Medicago sativa cv. Gabès): Comparison of upper and lower internodes

In M. sativa cv. Gabès plants treated with 150mM NaCl, the height of the stem is decreased and the internode number, length and diameter are reduced. This depressive effect on growth, but also on photosynthetic activity and water balance, is accompanied by structural changes. In the upper internodes, NaCl treatment increases cambium development, so that the vascular ring is initiated earlier than in controls. In the lower internodes, the number of lignified phloem fibers is increased by NaCl, and their wall thickness is augmented, compared to controls; in the phloem complex, the nacreous layer is enlarged, the number of internal wall ingrowths is increased, but companion cells are damaged. In the treated lower internodes, few vessels occur in the secondary xylem, which is by contrast rich in lignified fibers and in wide vessels grouped in the metaxylem area; protoxylem parenchyma and adjacent pith are also lignified. In addition, in treated lower internodes, starch grains are less abundant than in controls, and this variation might be related to the decrease of photosynthesis. When taken together, qualitative and quantitative results indicate that the saline stress has a marked morpho-anatomical impact on the M. sativa Gabès stem. In particular, variations of secondary derivative distribution, increased wall thickening, lignification of phloem and xylem fibers and damage in the phloem complex are NaCl-induced responses, and are more expressed in the lower than in the upper internodes. The reinforcement of the stem lignified vasculature is thus a positive response to stress, but it has a negative impact on the quality of the forage.

English

The present study assessed the response of physiological and anatomical characteristics of four widely cultivated fragrant Rosa species. Water analysis showed that all minerals and chemicals were in permissible level in canal water and treated wastewater, whereas untreated wastewater contained higher EC, biological oxygen demand (BOD), chemical oxygen demand (COD) and heavy metals like Cd, Co, Cu, Pb. There was considerable variations among different Rosa species regarding response to wastewater irrigations. Under treated wastewater, R. bourboniana showed highest photosynthetic rate, high transpiration rate and maximum chlorophyll contents than other Rosa species whereas stomatal conductance of R. Gruss-anTeplitz was highest under treated wastewater. Leaf anatomical characteristics showed that R. Gruss-an-Teplitz under untreated wastewater showed large cortical cell area, vascular bundle area, large spongy cell area and thick midrib while large epidermal thickness of R. centifolia was recorded under treated wastewater. Large palisade cell and phloem area and thick leaves (lamina) were found in R. damascena under treated wastewater while large metaxylem area of R. bourboniana in untreated wastewater. The study showed that treated wastewater was most suitable and desirable irrigation treatment than canal water and untreated wastewater while R. bourboniana and R. Gruss-an-Teplitz was dominant Rosa species regarding physiological characteristics, while all species showed great diversity in leaf tissue architecture under treated and untreated wastewater. © 2016 Friends Science Publishers

Adaptive components of tolerance to salinity in a saline desert grass Lasiurus scindicus Henrard

AbstractFive differently adapted natural populations of the native salt desert grass Lasiurus scindicus Henrard from Lesser Cholistan Desert (Pakistan) in South Punjab of east central Pakistan, were evaluated to examine their mechanism of adaptation to saline stress based on some key morpho–anatomical and physiological characteristics. Five ecotypes were collected from one saline site, two moderately saline sites, and two highly saline sites. Anatomical adaptations in each ecotype critically supported the physiological, but the adaptations were of specific nature depending on the type of each site's normal habitat conditions. Higher salinities resulted in increased Na+, Cl−, Mg2+, Ca2+ and K+ content in root and shoot. At root level, some specific structural modifications like increased sclerification in cortical and pith regions, endodermal thickness, and number and size of xylem vessels are vital for water conservation under osmotic stress. Several characteristics were promising for increasing the plants ability to deal with osmotic stress, including at the stem level, increased sclerification, stem area, cortical region thickness and vascular bundle area, and at the leaf level, significant structural modifications such as leaf thickness, epidermal thickness, sclerenchymatous area, cortical area, metaxylem area and bulliform cell area were promising. All these may contribute towards water conservation, which ultimately account for ecotype survival under saline–induced physiological droughts.