Leaf Proline Content Research Articles

Screening of ‘King’ mandarin (Citrus nobilis Lour) × Poncirus trifoliata ((L.) Raf.) hybrids as salt stress-tolerant citrus rootstocks

This work evaluates new citrus hybrid tolerance to salt stress compared to Carrizo citrange. Growth parameters, ion concentration, photosynthetic parameters, leaf water relation, plant damage and proline concentration were assessed in plants irrigated with 0 (control) or 60 mM of NaCl for 60 days. Some hybrids presented marked salt-stress symptomatology like sharp decreases in plant biomass and RGR parameter, and high leaf burn and abscission percentages. While Cl− accumulation in most salinised genotypes was recorded in all the plant fractions, accumulation occurred in some hybrids only in their aerial organs. Stomatal conductance also lowered under salt conditions in all the hybrids, whereas the internal CO2 concentration (Ci) tended to increase. Salt stress lowered the leaf water potentials in all the 0501 hybrids. As a response, the salinised plants induced proline accumulation. The main trait that improved salt tolerance in some genotypes is apparently linked with the imbalance among Cl−, Na+ and K+ ions, especially enhanced K+ uptake and transport rates which delay plant damage.

Leaf proline accumulation and fruit yield of ‘Pera’ sweet orange trees under natural water stress

The water deficit is one of the main limiting factors to the yield of sweet oranges. The present study aimed to determine alternative rootstocks to ‘Rangpur’ lime for ‘Pera’ sweet oranges grown on tropical hardsetting soils with greater potential tolerance to water deficit. Six citrus scion/rootstock combinations were grown during eight years in an orchard established in Sergipe, Brazil. The tree height, number of fruits per plant, cumulated fruit yield, leaf proline content and survival rate of trees were evaluated between 6th and 8th year after planting. Greater rate of tree loss occurred among the sweet orange onto ‘Orlando’ tangelo, which also induced the lowest cumulative fruit yield. After prolonged water deficit, moderate to high proline content was found in trees grafted on Sunki of Florida mandarin × C13 citrange – 012° (TSKFL × CTC13-012), ‘Orlando’ tangelo, ‘Indio’ and ‘Riverside’ citrandarin. Conversely, after a short water deficit during the wet season, trees on ‘San Diego’ citrandarin and Rangpur lime clone of Centro Nacional de Pesquisa Mandioca e Fruticultura – CNPMF 03 ‘Rangpur’ lime showed higher proline content. Trees onto TSKFL × CTC13-012 and ‘Indio’ also induced the greatest accumulated fruit yield at the 8th year after planting. It is assumed that ‘San Diego’ and CNPMF 03 ‘Rangpur’ induce response more quickly to water deficit, whereas TSKFL × CTC13-012 and ‘Indio’ are less susceptible to prolonged deficit. Therefore, trees on ‘San Diego’ and Indio citrandarin, CNPMF-03 ‘Rangpur’ lime, TSKFL × CTC13-012 hybrid present greater potential to tolerate water deficit and produce more fruits on the hardsetting soils of the coastal tablelands of the Brazilian Northeast.

Detecting QTL system of root hydraulic stress tolerance index at seedling stage in soybean

<p indent=0mm>Soybean is an important source of plant protein and vegetable oil in the world. Drought is one of the important environmental stress factors affecting soybean yield. To explore the genetic base of drought tolerance in soybean, a nested association mapping population composed of two sets of recombinant inbred lines with a common parent in a total of 429 lines was investigated for leaf proline content under PEG simulated drought stress. The genetic system of root hydraulic stress tolerance index (RHSTI) was analyzed using the RTM-GWAS (restrictive two-stage multilocus genome-wide association study). The results showed that there were significant differences in RHSTI among the three parents under two different environments in spring and summer, and among the nested association mapping population with the variation range of 0.11–2.94 and 0.03–1.93, respectively. The heritability values of Line and Line×Environment were 37.9% and 60.1%, respectively, indicating that the variation of RHSTI was greatly affected by the environment. Using the RHSTI data and 6137 SNPLDB markers, a total of 45 main effect QTLs were detected on 18 chromosomes, which could explain a total of 37.58% phenotypic variation, including 7 large contribution QTLs with <italic>R</italic>² more than 1%. Among them, 34 QTLs with QTL×Environment effect explained 12.50% of the phenotypic variation. Combined with the transcriptome data under PEG stress, totally 38 differentially expressed genes were identified within a QTL ± 500 kb, which can be grouped into different biological categories, including ABA responders, stress responders, transcription factors, development factors, protein metabolism factors, unknown functions and others, with stress responses, transcription factors and development factors as the major parts. In summary, the results indicated that the drought tolerance of soybean was a complex quantitative trait, with the complex genetic basis controlling by multiple loci, multiple genes and interaction with the environment. The present results can lay the foundation of molecular breeding for drought tolerance in soybean.

Comparative study on germination and seedling growth of wheat cultivars under salt stress regimes

Salinity interferes with germination and hampers the growth of wheat especially at seedling stage which necessitates determining of salt tolerant cultivars. Based upon the current situation a controlled experiment was carried out at the Laboratory of Horticulture, Faculty of Agriculture, Cukurova University, Turkey to comparatively evaluate wheat varieties response to imposed salt stress. Germination and seedling growth properties under salt stress were taken as response variables. The seeds of five bread wheat genotypes (‘Wafia’, ‘Lucilla’, ‘Envoy’, ‘Lok1’and ‘RSP- 561’) were placed in Petri dishes with salinity doses (Control (0), 4, 8 and 12 dS.m-1 NaCl) which were applied at germination and subsequent early seedling phases under laboratory conditions. The results revealed that root growth was highly sensitive to salt stress and the varieties of Envoy and Lucilla remained relatively tolerant to salt stress than other cultivars. The biochemical analysis revealed that proline content spiked with increasing salinity level, ‘RSP-561’ under 8 dS.m-1and 12 dS.m-1 recorded the maximum proline content. Salt stress boosted leaf proline content of salt sensitive wheat genotypes (‘Wafia’ and ‘Lok1’), whereas declined proline level was observed for salt tolerant cultivars. In addition, salt-sensitive genotypes showed a reduction in chlorophyll content a, b, total chlorophyll and carotenoid while, ‘Wafia’ and ‘RSP-561’ recorded the minimum Chlorophylls and Carotenoid contents. Further investigations are needed, however, to enhance understanding of the salt stress effects during the whole growing cycle of wheat.

Effects of exogenous \u03b1-oxoglutarate on proline accumulation, ammonium assimilation and photosynthesis of soybean seedling (Glycine max(L.) Merr.) exposed to cold stress

The objective of this study was to examine the effects of exogenous α-oxoglutarate on leaf proline accumulation, ammonium assimilation and photosynthesis of soybean when exposed to cold stress. To achieve this objective, exogenous α-oxoglutarate was sprayed to potted seedlings of Henong60 and Heinong48 at 0, 2.5, 5.0 and 7.5 mmol/L, identified as A0, A2.5, A5.0, and A7.5, respectively. Leaf samples were collected after cold stress of 24 h (S1 stage) and 48 h (S2 stage). The results indicated that exogenous α-oxoglutarate significantly enhanced leaf GS activity, NADP-GDH activity, glutamate content, proline content and photosynthesis of soybean seedling exposed to cold stress at S1 and S2 stages. The ammonium content in leaf was significantly decreased by exogenous α-oxoglutarate at both stages. 5.0 mmol/L of exogenous α-oxoglutarate is the optimum concentration in this study. Leaf proline content for Henong60 and Heinong48 at A5.0 was 37.53% and 17.96% higher than that at A0 at S1 stage, respectively. Proline content for Henong60 and Heinong48 increased by 28.82% and 12.41% at A5.0 and A0, respectively, at S2 stage. Those results suggested that exogenous α-oxoglutarate could alleviate the adverse effects of cold stress.

Some physiological and biochemical changes of micropropagated Rhynchostylis gigantea during ex vitro acclimatization and greenhouse stages

The ex vitro acclimatization and greenhouse periods play a significant role for the in vitro originated plantlets. In these stages, the micropropagated plantlets have to rapidly adapt to environmental changes. Rhynchostylis gigantea is widely in vitro produced due to highly aesthetic and economic value. The aim of this work was to update the physiological changes of micropropagated R. gigantea plantlets during ex vitro acclimatization and greenhouse stages. The analysis results showed that leaf water content was significantly decreased at day 14 (90.36%) and day 28 (90.17%) stages but increased at day 84 (92.52%) and day 140 (92.34%) stages in compared to in vitro stages, day 0 (92.7%). Dry matter content was changing in the opposite direction to the leaf water content with the highest values at day 14 (9.63%) and day 28 (9.83%), respectively. The leaf transpiration rate was the highest at day zero (0.146 g/dm2/h) in compared to all other studied points. Oppositively, GPX activity was the lowest in plantlets at day zero (13.2 UI/g fresh leaf ) and the highest in planlets at day 14 (36,4 UI/g fresh leaf ). The leaf proline content was higher at day 7 and day 14 stages (132.3 and 150.8 m g/g fresh leaf, respectively) but lower at day 84 and day 140 stages (44.3 and 53.3 microgram/g fresh leaf, respectively) than at day zero (73.7 microgram/g fresh leaf ).

Growth-Stimulatory Effect of Quorum Sensing Signal Molecule N-Acyl-Homoserine Lactone-Producing Multi-Trait Aeromonas spp. on Wheat Genotypes Under Salt Stress.

Salinity is one of the major threats to agricultural productivity worldwide. Soil and plant management practices, along with inoculation with plant-beneficial bacteria, play a key role in the plant’s tolerance toward salinity stress. The present study demonstrates the potential of acyl homoserine lactone (AHL)-producing plant growth promoting rhizobacteria (PGPR) strains of Aeromonas sp., namely, SAL-17 (accession no. HG763857) and SAL-21 (accession no. HG763858), for growth promotion of two wheat genotypes inherently different for salt tolerance potential. AHLs are the bacterial signal molecules that regulate the expression of various genes in bacteria and plants. Both Aeromonas spp., along with innate plant-growth-promoting (PGP) and salt tolerance traits, showed AHL production which was identified on tandem mass spectrometry as C6-HSL, 3-OH-C5-HSL, 3-OH-C6-HSL, 3-oxo-C7-HSL C10-HSL, 3-oxo-C10-HSL, 3-OH-C10-HSL, 3-oxo-C12-HSL and C6-HSL, and 3-oxo-C10-HSL. The exogenous application of purified AHLs (mix) significantly improved various root parameters at 200 mM NaCl in both salt-sensitive (SSG) and salt-tolerant (STG) genotypes, where the highest increase (≈80%) was observed where a mixture of both strains of AHLs was used. Confocal microscopic observations and root overlay assay revealed a strong root colonization potential of the two strains under salt stress. The inoculation response of both STG and SSG genotypes was evaluated with two AHL-producing strains (SAL-17 and SAL-21) and compared to non-AHL-producing Aeromonas sp. SAL-12 (accession no. HG763856) in saline (EC = 7.63 ms/cm2) and non-saline soil. The data reveal that plants inoculated with the bacterial consortium (SAL-21 + SAL-17) showed a maximum increase in leaf proline content, nitrate reductase activity, chlorophyll a/b, stomatal conductance, transpiration rate, root length, shoot length, and grain weight over non-inoculated plants grown in saline soil. Both STG and SSG showed relative effectiveness toward inoculation (percent increase for STG: 165–16%; SSG: 283–14%) and showed a positive correlation of grain yield with proline and nitrate reductase activity. Furthermore, principal component analysis (PCA) and categorical PCA analysis clearly showed an inoculation response in both genotypes, revealing the effectiveness of AHL-producing Aeromonas spp. than the non-AHL-producing strain. The present study documents that the consortium of salt-tolerant AHL-producing Aeromonas spp. is equally effective for sustaining the growth of STG as well as SSG wheat genotypes in saline soil, but biosafety should be fully ensured before field release.

Physiological responses of watercress to brackish waters and different nutrient solution circulation times

Water scarcity and the use of brackish water are the main challenges for agricultural development. In view of this, the present study proposes to examine physiological responses of the broadleaf-cress crop in an NFT hydroponics system according to the use of brackish water and nutrient solution circulation times. The treatments were distributed in a randomized block design with five water salinity levels (ECw: 0.6, 1.6, 2.6, 3.6 and 4.6 dS m-1) and two nutrient solution circulation times (T1 = 10 min and T2 = 15 min), totaling 10 treatments with four replicates, which resulted in 40 experimental plots. The following variables were analyzed: net photosynthetic rate, stomatal conductance, transpiration, leaf proline content, shoot moisture content, stem diameter and root length. The maximum observed photosynthetic rates were 20.9 mmol m-2 s-1 (T1) and 20.0 mmol m-2 s-1 (T2). Maximum stomatal conductance was 0.44 mol m-2 s-1, which decreased by 63.4% at the highest salinity level. The increasing ECw levels in both growing cycles evaluated reduced gas exchanges, stem diameter and root length. The nutrient solution circulation time of 15 min provided the most satisfactory results for the analyzed variables.

Effect of Vanadium on Testa, Seed Germination, and Subsequent Seedling Growth of Alfalfa (Medicago sativa L.)

Seed germination is the critical initial phase in the life cycle of plant and it is affected by various exogenous factors, including heavy metals. Seed germination and subsequent seedling growth of alfalfa (Medicago sativa L.) incubated in glass Petri dish in presence of elevated concentrations of pentavalent vanadium V(V) solution (0, 0.1, 0.5, 2, 4, 10, 50 mg L−1 V, supplied as NaVO3·2H2O) were evaluated. Results showed that vanadium did not (P > 0.05) affect seed germination, final survival rate, and seedling height of alfalfa when exogenously treated dosages were ≤ 10 mg L−1 V, whereas the root vitality and root elongation were distinctly inhibited at ≥ 0.5 mg L−1 V treatments. A progressively deepened testa color at increasing vanadium concentrations during germination and an apparent modified structure of the seed coat at 50 mg L−1 V compared to control in alfalfa were noted. Alfalfa seeds showed rapid and almost synchronous radicle emergence, independently of the vanadium concentration in the medium. The accumulation of vanadium in testa is beneficial to alleviate its toxicity to the seed germination of alfalfa. Leaf proline content was dramatically increased at ≥ 0.5 mg L−1 V treatments compared with the control. Emerged seedlings displayed enough vigor and health to potentially colonize in the vanadium-contained matrix. Thus, alfalfa represents a good candidate for phytoremediation approach aimed at decontaminating environments when vanadium concentrations are within the determined thresholds.

RESPONSE OF PEAR SEEDLINGS TO SOME NON-AND MAGNETIZED SALINE IRRIGATION WATER AND HUMIC ACID AND THEIR EFFECT ON GROWTH, LEAF PHYSIOLOGICAL PROPERTIES, LEAF PIGMENTS AND ELEMENTS CONTENTS

This study was conducted during two successive seasons of 2018 and 2019 at El Kanater Horticultural Research Station, Qalyoubeia Government Egypt. The aim of this investigation was to study the effect of salinity levels of non-and magnetized irrigation water alone and in combination with humic acid on one-year-old pear seedlings (Pyrus communis) rootstock. Obtained results revealed that, the two higher concentrations of saline water (1500 and 3000 mg/l) resulted in a gradual significant decreased in all vegetative measurements, dry weights of pear seedling organs, both leaf succulence grade, water potential and leaf content of pigments as well as some leaf elements contents of N, P, K, Mg, Fe, Zn and Mn, Whereas an opposite trends were observed with leaf osmotic pressure, proline content and leaf content of Ca, Na and Cl as compared to the control (270 mg/l –fresh water). On the other hand, seedlings treated with either humic acid or magnetized water were exited significantly an increasing values of vegetative parameters, dry weights of different plant organs, leaf pigments and some macro and micro-nutrients beside Na and Cl as well as both leaf succulence grade and water potential as compared to control (non-magnetized water or non-humic acid) in both seasons of study. The obtained data concluded that the use of magnetized water technique with humic acid applications would be efficiently and safe alternative tool to resolve the problem of irrigating with saline water and to enhance pear rootstock seedlings growth grown under similar conditions of this study.

Strong positively diversity\u2013productivity relationships in the natural sub-alpine meadow communities across time are up to superior performers

In experiments that test plant diversity–productivity relationships, the common practice of weeding unsown species and disallowing species colonization may have the unintended consequence of favoring priority effects that maintain niche complementarity in determining productivity. However, in naturally assembled communities where colonization occurs, resource competition may favor dominant traits, which eventually have the greatest influence on productivity. Here, in naturally developed long-term subalpine meadows (from 4-year to at least 40 years meadows) in the Qinghai-Tibetan Plateau, we investigated the relationships between species richness and productivity to testify whether positive diversity–productivity relationships can still exist in naturally developed long-term communities. We also measured five functional traits (specific leaf area, photosynthesis rate, leaf proline content, seed mass and seed germination rate) to calculate two functional diversity indices: community-weighted mean trait values (CWM) and Rao’s quadratic entropy (RaoQ) which are highly correlated to functional traits of dominating species and variety of functional trait among all species. Finally, we quantified the relative contribution of species diversity, functional traits of dominating species and functional diversity among all species to productivity along the succession. We demonstrated strong positively diversity–productivity relationships in the natural sub-alpine meadow communities across time. The five traits of dominating species explained a large proportion (54–80%) of the variation in productivity during succession, whereas species diversity and functional diversity (FD) for each of the five traits explained much less (24–48% for species richness and 0–40% for FD for each of the five traits respectively). We found unequivocal evidence that significantly positive diversity–productivity relationships in the natural sub-alpine meadow communities across time are up to superior performers (dominant traits) in naturally developed communities where colonization occurs. As a result, understanding diversity–productivity relationships under the full range of community assembly processes therefore merits further investigation.

Hormopriming instigates defense mechanisms in Thyme (Thymus vulgaris L.) seeds under cadmium stress

Seed germination and root development are vital phases of the plant growth process; however, these steps are strongly influenced by the seed characteristics and environmental conditions. Seed priming provides a condition for uniform and rapid germination and plant establishment. Limited studies are available on the effect of seed priming to ameliorate cadmium (Cd) stress in thyme plants. Hence, the effect of seed hormopriming (salicylic acid and jasmonic acid, 100 mg.l−1) was evaluated. Hydropriming was done using double distilled water. Seed priming significantly increased the seed germination percentage (GP) and germination rate (GR) at all stress levels of Cd contamination. SA-primed seed showed the greatest increase in GP and GR at 30 mg.l−1 Cd by 26 and 37 %, respectively, compared with the control. Salicylic acid (SA) increased plumule and radicle length 29 and 43 %, respectively, at 30 mg.l−1 of Cd concentration compared with the control seeds. SA pretreatment increased plumule dry weight more than radicle dry weight. The leaf antioxidant enzyme activity was increased with increasing Cd concentration. Seed priming with SA increased superoxide dismutase (SOD) and peroxidase (POX) activity by 14 and 15 %, respectively. Leaf malondialdehyde (MDA) content was increased 15 % at 30 mg.l−1 Cd concentration compared with the control plants, but SA priming reduced leaf MDA content 18 % compared with the control seeds. The greatest leaf proline content was observed at 30 mg.l−1 Cd concentration and SA priming. Regardless of the priming treatment, the greatest leaf protein content was observed at 10 mg.l−1 Cd concentration compared with the control. Seed priming with SA diminished the adverse effects of Cd on germination process via enhancing the antioxidant activities and accumulation of osmolytes. Therefore, hormopriming of thyme seeds by SA can enhance the resistance of this valuable medicinal herb to cadmium stress.

KARAKTER MORFOLOGI DAN FISIOLOGI TAPAK DARA (Vinca rosea L.) PADA BEBERAPA CEKAMAN AIR

&lt;p&gt;&lt;strong&gt;Morphological and physiological characteristics of Vinca at di fferent water stress levels&lt;/strong&gt;&lt;/p&gt;&lt;p&gt;Vinca (Vinca rosea L.) is one of the important medicinal crops as the sources of raw materials for traditional medicines. Its alkaloid is believed can reduce the risk of cancer, blood tension and diabetes diseases. Recently, vinca is only grown as ornamental plant in the garden, therefore, its cultivation methods is limited, especially its water stress tolerance, lite purpose of this experiment was to study the effect of water stess on the morphological and physiological characteristics of vinca. A pot experiment was conducted in the plastics house of the Research Institute for Spice and Medicinal Crops from November 1997 to March 1998. Factorial experiment consisted two factors and three replications was arranged in a randomized block design. Ihe irst factor consisted of two vinca varieties, those wee white flowers (WFV) and red flowers of vinca (RFV). While 4 different levels of water stress i.e., (I) 100% ield capacity (FC), (2) 80% FC, (3) 60% FC, and (4) 40% FC were used as the second factor. Parameters used for evaluating the effect of teatment consisted of morphological characteristics such as (I) plant height, (2) number of primary branches, (3) number of leaves, (4) leaf area (5) dry weight of stem, (6) dry weight of leaf, (7) dry weight of flowers and (8) dry weight of roots, and physiological characteristics observed including: (I) percentages of opened stomata and (2) free proline content of leaf. Results showed that interaction between varieties and water stress did not significantly affect the morphological nor physiological characteristics. Varieties significantly affected the morphological characteristics (except plant height), however they did not signiicantly affect physiological characteristics. Water stress significantly affected the morphological (except dry weight of roots) and free proline contents. Under 80% FC, vinca produced the highest growth and dry weight of plant however, the plant growth and dry weight wee inhibited under 60 and 40% FC. Under 40% FC, percentages of opened stomata deceased signiicantly. Moeover, proline content in the leaves signiicantly increased by water stess treatments.&lt;/p&gt;

Red elemental selenium nanoparticles mediated substantial variations in growth, tissue differentiation, metabolism, gene transcription, epigenetic cytosine DNA methylation, and callogenesis in bittermelon (Momordica charantia); an in vitro experiment.

To gain a better insight into the selenium nanoparticle (nSe) benefits/toxicity, this experiment was carried out to address the behavior of bitter melon seedlings to nSe (0, 1, 4, 10, 30, and 50 mgL-1) or bulk form (selenate). Low doses of nSe increased biomass accumulation, while concentrations of 10 mgL-1 and above were associated with stem bending, impaired root meristem, and severe toxicity. Responses to nSe were distinct from that of bulk in that the nano-type exhibited a higher efficiency to stimulate growth and organogenesis than the bulk. The bulk form displayed higher phytotoxicity than the nano-type counterpart. According to the MSAP-based analysis, nSe mediated substantial variation in DNA cytosine methylation, reflecting the epigenetic modification. By increasing the concentration of nSe, the expression of the WRKY1 transcription factor linearly up-regulated (mean = 7.9-fold). Transcriptions of phenylalanine ammonia-lyase (PAL) and 4-Coumarate: CoA-ligase (4CL) genes were also induced. The nSe treatments at low concentrations enhanced the activity of leaf nitrate reductase (mean = 52%) in contrast with the treatment at toxic concentrations. The toxic concentration of nSe increased leaf proline concentration by 80%. The nSe supplement also stimulated the activities of peroxidase (mean = 35%) and catalase (mean = 10%) enzymes. The nSe-treated seedlings exhibited higher PAL activity (mean = 39%) and soluble phenols (mean = 50%). The nSe toxicity was associated with a disrupted differentiation of xylem conducting tissue. The callus formation and performance of the explants originated from the nSe-treated seedlings had a different trend than that of the control. This experiment provides new insights into the nSe-associated advantage/ cytotoxicity and further highlights the necessity of designing convincing studies to introduce novel methods for plant cell/tissue cultures and agriculture.

Exogenous proline enhances salt tolerance in acclimated Aloe vera by modulating photosystem II efficiency and antioxidant defense

This study investigated the ameliorating effect of exogenous proline on some physiological responses of salt acclimated and non-acclimated Aloe vera plants against subsequent salt stress (EC 21 dS/m). Compared to control, salinity decreased leaf growth and relative water content (RWC), leaf contents of chlorophyll a, carotenoids, K/Na ratio, photosystem performance index (PIabs), while promoted leaf contents of hydrogen peroxide (H2O2), maloendialdehyde (MDA) and Na, which subsequently induced oxidative stress. However, foliar applied proline was effective in alleviating the deleterious effects of salinity. Maximum amelioration of salt stress by exogenous proline was found only in salt-acclimated plants, which was attributed to the reduced leaf Na accumulation together with enhanced K content. Proline pretreatment improved plant relative water content, which was correlated with enhancement in leaf proline concentration. We showed that application of proline on salt-acclimated stressed plants alleviated the damage to PSII functioning induced by salinity, contributing to the improvement of the oxygen-evolving complex efficiency of PSII (Fv/Fo) and the quantum yield of electron transport (ΦEo). This improvement of PSII activity was achieved by higher carotenoids and phenolic accumulation. Additionally, proline treatment reduced the accumulation of H2O2 and MDA, indicating that proline pretreatment was more effective in lowering oxidative damage in salt-exposed acclimated plants, which was associated with the activation of SOD, CAT and APX enzymes. Thus, proline pretreatment could protect salt acclimated Alo vera plants against subsequent salt stress through improving K/Na ratio and water relations attributes as well as enhancing antioxidant systems, resulting in better photosynthesis under salt stress.

Salinity induced deleterious effects on germination, growth, physiological and biochemical process of two varieties of groundnut (Arachis hypogaea L.)

The present study was accomplished to find out the effects of salinity on germination, growth, physiological and biochemical processes of two different groundnuts (Arachis hypogaea L.), varieties viz., Dacca-1, and Zhinga groundnut. The experiments consisted of five salinity treatments viz., control (no salinity), 3, 6, 9, and 12dS/m during germination and vegetative stage of groundnut varieties. Results showed that germination percentage of both the groundnut varieties was significantly decreased with the increase of salt concentration. During the germination stage, maximum shoot and root length, shoot and root fresh weight and shoot and root dry weight of groundnut varieties were recorded from Zhinga groundnut variety at salt stress. The same result occurred during the vegetative stage of Dacca-1 variety while the Zhinga groundnut variety showed maximum parameters than Dacca-1. Fresh weight, as well as dry weight, of shoots and roots of both the groundnut varieties was also decreased with the increase of salt concentrations while leaf proline concentrations were increased among these varieties. Salinity caused significant (P&lt;0.001) reduction in chlorophyll a, chlorophyll b, and total chlorophyll content in both the genotypes. Between two genotypes, Zhinga groundnut recorded higher chlorophyll a, chlorophyll b and total chlorophyll content than Dacca-1. From the studies, it is concluded that the groundnut genotype Zhinga was identified as the tolerant genotype to salt stress than Dacca-1. Overall results indicate that high salinity condition is not suitable for growing the groundnut.

Tolerance and determinants of drought character descriptors of the Madurese landrace bambara groundnut (Vigna subterranea)

Abstract. Fatimah S, Ariffin, Rahmi AN, Kuswanto. 2020. Tolerance and determinants of drought character descriptors of the Madurese landrace bambara groundnut (Vigna subterranea). Biodiversitas 21: 3108-3116. Bambara groundnut (Vigna subterranea L. Verdc.) is legume of African origin overlooked in Indonesia. It has underdeveloped in Indonesia; for example, in East Java, it is only cultivated in Gresik, Lamongan, and Bangkalan of Madura. This plant can potentially be developed in dry lands, such as Madura as it has the ability to grow and develop well in a dry environment with low nutrient level. At present, there are sparse researches on the selection and determination of the drought-tolerant character descriptors of bambara groundnut in Indonesia. The present study used the expected lines of bambara groundnut selected from local lines of various regions in Indonesia using the nested design. The results showed that the drought stress treatment led to stunted growth of 12 bambara groundnut genotypes, including the number of leaves, plant height, canopy diameter, leaf thickness, number of flowers, number of stems or branches, number of internodes, length of leaf stems, root length, root wet weight, canopy wet weight, canopy dry weight, root dry weight, and leaf chlorophyll content. However, drought leads to a slight increase in the width and length of the stomata opening and leaf proline contents. The cluster analysis based on stress index and sensitivity index can classify 3 expected lines originating from Gresik Regency (G1, G2, G3), falling into the drought stress-tolerant category. Accumulated proline contents cannot be used as a descriptor of tolerance to drought stresses in bambara groundnut since the expected lines with an increase in proline contents in leaves during drought stresses based on the cluster analysis do not fall into the genotypic cluster tolerant to drought stresses.

Tolerance of fifteen hydroponic ornamental plant species to formaldehyde stress

An indoor formaldehyde enriched environment was created by an automatic fumigation system with timing and concentration control. Selected hydroponic plant species were exposed in formaldehyde concentrations of 10 mg m−3, 50 mg m−3 and 100 mg m−3 respectively for 6 days with 10-h-treatment each day. Changes in morphological characteristics including leaf damage rate, leaf damage time and survival rate were monitored to evaluate morphological resistance to formaldehyde. Assessed physiological parameters were leaf chlorophyll content (Chl), leaf malondialdehyde content (MDA), activity of leaf formaldehyde dehydrogenase (FADH), leaf water soluble sugar content (WSS), and leaf proline content (Pro). Under formaldehyde suppression, reduction of Chl and increase of MDA and Pro were observed. Varying by species, FADH and WSS peaked at certain formaldehyde concentrations. A Principal Component Analysis (PCA) method was adopted to evaluate key factors in hydroponic plants’ tolerance to formaldehyde. Among the 15 species selected, the best 5 performing species are Spathiphyllum floribundum, Alocasia cucullata, Davallia bullata, Syngonium podophyllum ‘Pixie’, and Schefflera octophylla. The study helps people to select the best ornamental plants for indoor air pollution control.The response of hydroponic plant species to formaldehyde was studied for eco-friendly indoor air pollution control.

The Use of Proline in Screening for Tolerance to Drought and Salinity in Common Bean (Phaseolus vulgaris L.) Genotypes

The selection of stress-resistant cultivars, to be used in breeding programmes aimed at enhancing the drought and salt tolerance of our major crops, is an urgent need for agriculture in a climate change scenario. In the present study, the responses to water deficit and salt stress treatments, regarding growth inhibition and leaf proline (Pro) contents, were analysed in 47 Phaseolus vulgaris genotypes of different origins. A two-way analysis of variance (ANOVA), Pearson moment correlations and principal component analyses (PCAs) were performed on all measured traits, to assess the general responses to stress of the investigated genotypes. For most analysed growth variables and Pro, the effects of cultivar, treatment and their interactions were highly significant (p &lt; 0.001); the root morphological traits, stem diameter and the number of leaves were mostly due to uncontrolled variation, whereas the variation of fresh weight and water content of stems and leaves was clearly induced by stress. Under our experimental conditions, the average effects of salt stress on plant growth were relatively weaker than those of water deficit. In both cases, however, growth inhibition was mostly reflected in the stress-induced reduction of fresh weight and water contents of stems and leaves. Pro, on the other hand, was the only variable showing a negative correlation with all growth parameters, but particularly with those of stems and leaves mentioned above, as indicated by the Pearson correlation coefficients and the loading plots of the PCAs. Therefore, in common beans, higher stress-induced accumulation of Pro is unequivocally associated with a stronger inhibition of growth; that is, with a higher sensitivity to stress of the corresponding cultivar. We propose the use of Pro as a suitable biochemical marker for simple, rapid, large-scale screenings of bean genotypes, to exclude the most sensitive, those accumulating higher Pro concentrations in response to water or salt stress treatments.

High-Throughput Screening of Free Proline Content in Rice Leaf under Cadmium Stress Using Hyperspectral Imaging with Chemometrics.

Tracking of free proline (FP)—an indicative substance of heavy metal stress in rice leaf—is conducive to improve plant phenotype detection, which has important guiding significance for precise management of rice production. Hyperspectral imaging was used for high-throughput screening FP in rice leaves under cadmium (Cd) stress with five concentrations and four periods. The average spectral of rice leaves were used to show differences in optical properties. Partial least squares (PLS), least-squares support vector machine (LS-SVM) and extreme learning machine (ELM) models based on full spectra and effective wavelengths were established to detect FP content. Genetic algorithm (GA), competitive adaptive weighted sampling (CARS) and PLS weighting regression coefficient (Bw) were compared to screen the most effective wavelengths. Distribution map of the FP content in rice leaves were obtained to display the changes in the FP of leaves visually. The results illustrated that spectral differences increased with Cd stress time and FP content increased with Cd stress concentration. The best result for FP detection is the ELM model based on 27 wavelengths selected by CARS and Rp is 0.9426. Undoubtedly, hyperspectral imaging combined with chemometrics was a rapid, cost effective and non-destructive technique to excavate changes of FP in rice leaves under Cd stress.