Accumulation Of Proline Content Research Articles

EFFECT OF SUBMERGENCE STRESS ON AGRO-MORPHOLOGICAL AND PHYSIOLOGICAL TRAITS IN RICE (ORYZA SATIVA L.) GENOTYPES

Submergence stress due to flash flooding is one of the most adverse abiotic factor of plant growthand productivity, considered a severe threat for sustainable crop production in the changing climate. Riceis semi-aquatic crop, able to make several modulations in their adaptive traits to sustain submergence stress,but intense and prolonged flooding is fatal for its sustainability. In this context, a field experiment wasconducted to assess the effect of different submergence regimes (7, 14 and 21 days’ submergence) on agromorphologicaland physiological traits in rice at ICAR-National Rice Research Institute, Cuttack, India. Theexperiment was laid out in a Complete Randomized Design with three replications. Control (nosubmergence) and submergence (7, and 14 days) were imposed on eleven rice genotypes at vegetative stage.Plant height, number of tillers hill-1, spikelets fertility, % survival, chlorophyll content, total soluble sugarcontent showed decreasing trend under submergence, whereas, accumulation of proline content and ADHactivities reported enhanced level under submergence, especially in Sub1 carrying lines. From the currentresearch, it was observed that submergence stress affected plant growth stages substantially, therefore,genotypes showed least vulnerability under seven days’ submergence might be utilized in traitsimprovement program.

Impact of simulated acid rain on the growth of three species Brassica integrifolia, Brassica rapa, Brassica juncea in Hanoi, Vietnam.

Over the past decade, the extent and magnitude of acid rain in Vietnam and other Asian countries have become more apparent. In this study, the effect of simulated acid rain (pH 5.0, 4.0, and 3.0) and control treatment (pH 6.0) are observed for three species Brassica integrifolia, Brassica rapa, and Brassica juncea in Hanoi. The pot experiment was conducted for 42days and arranged according to a randomized complete block design (RCBD), replicated 3 times with acid rain exposure being supplied every 4days. The results show that acid rain causes direct damage to leaves. Observations reveal white spots on leaves; leaves getting discolored and gradually turning yellow, curling leaf marginals, and turning dark blue, with the most severe symptoms being necrotic leaves. Parameters of the shoot and root length, leaf area, biomass, and chlorophyll content all decrease as pH drops. However, the accumulation of proline content in leaves tends to increase with greater acidity. In conclusion, Brassica rara has the highest resistance capability to acid rain compared with Brassica integrifolia and Brassica juncea, especially its proline content is the highest at pH 3.0 in three Brassicaceae species.

Polyethylene Gycol (PEG) Induced Water Stress in Four Different Genotypes of Pea Seedlings and Evaluation of The Induced Defense Mechanism

The present work was undertaken on artificially induced water stress on pea seedlings under in vitro conditions in order to select the drought tolerant line. Artificial water stress was induced with PEG-6000 on 15-day old seedlings of four varieties for 4, 8 and 12 days. The activities of antioxidative enzymes like peroxidase, catalase, ascorbate peroxidase, glutathione reductase and superoxide dismutase were assayed in the stressed and control plants. POX activity was increased in the initial stages of stress, but its activity was decreased significantly on the 12th day in all the varieties. APOX also showed a similar trend but the maximum activity was noted in Var 3 on the 8th day. CAT activity decreased in var 1 and var 2 when compared with the control, which, however, increased significantly in var 3 and var 4. A slight increase in the GR activity was observed in var 1 and var 2 at the initial stages of the drought stress but its activity decreased significantly on the 12th day in both these varieties when compared with control plants. However, its activity also increased steadily in var 3 and var 4. Maximum SOD activities were noted on the 4th day of drought stress in all four varieties but its activities decreased steadily on the subsequent 8th and 12th days when compared with control. When antioxidative activities were compared among the four varieties, var 3 and var 4 showed maximum increase in antioxidant activity during the period of drought stress. Among the four varieties, var 3 and var 4 showed greater accumulation of H2O2 during the stress days and were maximum at 12th day. Lipid peroxidation also increased in the same varieties. Maximum proline content was noted in both the root and leaf of var 3, followed by var 4. It was further noted that the chlorophyll content decreased significantly in all four varieties in subsequent longer drought stresses. The accumulation of proline content was steadily higher with an increase in the stress length in all the four varieties. During the drought stress, all the varieties showed an increase in ascorbate content but, it was maximum in var 4 followed by var 3 and the least ascorbate was noted in var 1. The present findings indicate that water stress induces oxidative stress in all the four varieties. However, antioxidative mechanisms were found to be more pronounced in var 4 which, therefore, may be considered as the most tolerant to drought stress.

Rubisco activase A (RcaA) is a central node in overlapping gene network of drought and salinity in Barley (Hordeum vulgare L.) and may contribute to combined stress tolerance

Co-occurrence of abiotic stresses, especially drought and salinity, is a natural phenomenon in field conditions and is worse for crop production than any single stress. Nowadays, rigorous methods of meta-analysis and systems biology have made it possible to perform cross-study comparisons of single stress experiments, which can uncover main overlapping mechanisms underlying tolerance to combined stress. In this study, a meta-analysis of RNA-Seq data was conducted to obtain the overlapping gene network of drought and salinity stresses in barley (Hordeum vulgare L.), which identified Rubisco activase A (RcaA) as a hub gene in the dual-stress response. Thereafter, a greenhouse experiment was carried out using two barley genotypes with different abiotic stress tolerance and evaluated several physiochemical properties as well as the expression profile and protein activity of RcaA. Finally, machine learning analysis was applied to uncover relationships among combined stress tolerance and evaluated properties. We identified 441 genes which were differentially expressed under both drought and salinity stress. Results revealed that the photosynthesis pathway and, in particular, the RcaA gene are major components of the dual-stress responsive transcriptome. Comparative physiochemical and molecular evaluations further confirmed that enhanced photosynthesis capability, mainly through regulation of RcaA expression and activity as well as accumulation of proline content, have a significant association with combined drought and salinity stress tolerance in barley. Overall, our results clarify the importance of RcaA in combined stress tolerance and may provide new insights for future investigations.

Transcriptome Profiling, Biochemical and Physiological Analyses Provide New Insights towards Drought Tolerance in Nicotiana tabacum L.

Drought stress is one of the main factors limiting crop production, which provokes a number of changes in plants at physiological, anatomical, biochemical and molecular level. To unravel the various mechanisms underpinning tobacco (Nicotiana tabacum L.) drought stress tolerance, we conducted a comprehensive physiological, anatomical, biochemical and transcriptome analyses of three tobacco cultivars (i.e., HongHuaDaJinYuan (H), NC55 (N) and Yun Yan-100 (Y)) seedlings that had been exposed to drought stress. As a result, H maintained higher growth in term of less reduction in plant fresh weight, dry weight and chlorophyll content as compared with N and Y. Anatomical studies unveiled that drought stress had little effect on H by maintaining proper leaf anatomy while there were significant changes in the leaf anatomy of N and Y. Similarly, H among the three varieties was the least affected variety under drought stress, with more proline content accumulation and a powerful antioxidant defense system, which mitigates the negative impacts of reactive oxygen species. The transcriptomic analysis showed that the differential genes expression between HongHuaDaJinYuan, NC55 and Yun Yan-100 were enriched in the functions of plant hormone signal transduction, starch and sucrose metabolism, and arginine and proline metabolism. Compared to N and Y, the differentially expressed genes of H displayed enhanced expression in the corresponding pathways under drought stress. Together, our findings offer insights that H was more tolerant than the other two varieties, as evidenced at physiological, biochemical, anatomical and molecular level. These findings can help us to enhance our understanding of the molecular mechanisms through the networks of various metabolic pathways mediating drought stress adaptation in tobacco.

Fall Ethephon Application Enhances the Freezing Tolerance of Magnolia wufengensis During Overwintering

Magnolia wufengensis L.Y. Ma et L. R. Wang, a rare species which has been introduced and cultivated from southern China to northern China, frequently suffers from freezing injuries. To figure out the influence of ethephon (ETH) application on the cold tolerance during the natural overwintering of M. wufengensis, one-year shoots subjected to ethephon application at four concentrations (0, 700, 1000, and 1500 mg·L−1) were collected to measure the physiological and biochemical changes from September 2017 to 1 April 2018. The fall ETH application increased the freezing tolerance of M. wufengensis, and the optimum concentration for M. wufengensis was 1000 mg·L−1 (T2), which not only improved the shoot freezing tolerance by 1.4 times, but also led to a 25.0% faster cold acclimation rate and 13.7% slower de-acclimation rate. Moreover, 1000 mg·L−1 ETH delayed bud-burst in the spring by 10. 7 d, which was helpful for effectively avoiding cold spells in the spring, and improved the rates of bud survival by 47.1%. The improved freezing tolerance under exogenous ETH application was associated with an increased dehydration and accumulation of proline content. It seems that exogenous ETH application may be used on M. wufengensis grown in northern China to protect against freezing tolerance during the overwintering period.

GmFAD3A, A ω-3 Fatty Acid Desaturase Gene, Enhances Cold Tolerance and Seed Germination Rate under Low Temperature in Rice.

Low temperature is an environmental stress factor that is always been applied in research on improving crop growth, productivity, and quality of crops. Polyunsaturated fatty acids (PUFAs) play an important role in cold tolerance, so its genetic manipulation of the PUFA contents in crops has led to the modification of cold sensitivity. In this study, we over-expressed an ω-3 fatty acid desaturase from Glycine max (GmFAD3A) drove by a maize ubiquitin promoter in rice. Compared to the wild type (ZH11), ectopic expression of GmFAD3A increased the contents of lipids and total PUFAs. Seed germination rates in GmFAD3A transgenic rice were enhanced under low temperature (15 °C). Moreover, cold tolerance and survival ratio were significantly improved in GmFAD3A transgenic seedlings. Malondialdehyde (MDA) content in GmFAD3A transgenic rice was lower than that in WT under cold stress, while proline content obviously increased. Meanwhile, the activities of superoxide dismutase (SOD), hydroperoxidase (CAT), and peroxidase (POD) increased substantially in GmFAD3A transgenic rice after 4 h of cold treatment. Taken together, our results suggest that GmFAD3A can enhances cold tolerance and the seed germination rate at a low temperature in rice through the accumulation of proline content, the synergistic increase of the antioxidant enzymes activity, which finally ameliorated the oxidative damage.

Over-expression of a protein disulfide isomerase gene from Methanothermobacter thermautotrophicus, enhances heat stress tolerance in rice

High temperature (HT) stress is a major environmental stress that limits agricultural production worldwide. Discovery and application of genes promoting high temperature tolerance is essential to enhance crop tolerance to heat stress. Proteins associated with chaperone and protein folding plays an important role in the high temperature stress response of plants. MTH1745 (MtPDI), a disulfide isomerase-like protein (PDI) with a chaperone function and disulfide isomerase activity from Methanothermobacter thermautotrophicus delta H, was selected for studying the heat stress tolerance using an ectopic expression method in rice. Through molecular identification via quantitative real-time PCR and western blot, we demonstrated that the MtPDI gene was expressed stably in transgenic rice. Heat stress tolerance and survival ratio were significantly improved in seedling transgenic rice. At the same time, proline content, superoxide dismutase (SOD) and peroxidase (POD) activities were increased in MtPDI transgenic rice with a reduced malondialdehyde (MDA) content. Moreover, increased content of thiols group was discovered in transgenic plants. These results indicate that heterologous expression of MtPDI from extremophiles could confer heat stress tolerance of transgenic rice through the accumulation of proline content, the synergistic increase of the antioxidant enzymes activity and elevated production of more thiols group, which finally ameliorated the oxidative damage.

Effect of Drought Stress on the Growth and Development of Saffron (Crocus Sativus. L) in Eastern Morocco

Saffron (Crocus sativus L.; Iridaceae) is the most expensive spice in the world. It has been cultivated in Morocco for centu-ries and has represented a traditional staple for culinary, medical and cosmetic uses. The present work is about the study of the effect of drought stress on Saffron’s mor-pho-physiological and biochemical param-eters. An experiment has been carried out on a 4-year-old saffron plantation planted in an open field located in the experimental station of the Faculty of Sciences of Oujda. The experimental treatment included three water regimes (T0: Control receiving 100% ET0, T1: moderate water deficit receiving 60% ET0, T2: pronounced water deficit re-ceiving only 40% ET0). The results show that the increase in drought stress levels has slightly influenced the different param-eters of saffron growth. At the foliar level, the effect of stress has resulted in a de-crease in the chlorophyll content, a slight decrease in the PSII quantum yield and a Proline content accumulation as soluble sugars and total phenols, which resulted in keeping the relative water content (RWC) and the Malondialdehyde (MAD) content at a level similar to that of the control. In gen-eral, the morpho-physiological adaptation traits were observed even at severe level of water stress (40% ET0) which resulted in an acceptable decrease in stigmas yield.

Upregulation of Superoxide Dismutase and Catalase along with Proline Accumulation Mediates Heat Tolerance in Lentil (Lens culinaris Medik.) Genotypes during Reproductive Stage

Heat stress during reproductive stage of lentil leads to array of physiological and morphological changes affecting lentil production. The effect of high temperature stress (30°-35°) was studied on thirty three lentil genotypes during winter (rabi) trial 2013–2014. Six genotypes comprising three tolerant (LL1372, LL1361, LL1396) and three sensitive (EC78390, LL1380, LL1390) were selected which further raised under timely sown (TS) and late sown (LS) conditions during winter (rabi) trial 2014–15 for biochemical analysis. The higher accumulation of proline content along with higher activities of superoxide dismutase (SOD) and catalase (CAT) was observed in late sown tolerant genotypes, might be helping in reducing oxidative stress caused by reactivite oxygen species (ROS). The higher accumulation of malondialdehyde (MDA) and hydrogen peroxide (H2O2) content was found in sensitive genotypes might be responsible for membrane damage. The positive and significant correlation was observed in CAT, SOD, and proline whereas these three biochemical parameters showed negative correlation with MDA and hydrogen peroxide content.

Application of Plant-Growth-Promoting Fungi Trichoderma longibrachiatum T6 Enhances Tolerance of Wheat to Salt Stress through Improvement of Antioxidative Defense System and Gene Expression.

Soil salinity is a serious problem worldwide that reduces agricultural productivity. Trichoderma longibrachiatum T6 (T6) has been shown to promote wheat growth and induce plant resistance to parasitic nematodes, but whether the plant-growth-promoting fungi T6 can enhance plant tolerance to salt stress is unknown. Here, we determined the effect of plant-growth-promoting fungi T6 on wheat seedlings’ growth and development under salt stress, and investigated the role of T6 in inducing the resistance to NaCl stress at physiological, biochemical, and molecular levels. Wheat seedlings were inoculated with the strain of T6 and then compared with non-inoculated controls. Shoot height, root length, and shoot and root weights were measured on 15 days old wheat seedlings grown either under 150 mM NaCl or in a controlled setting without any NaCl. A number of colonies were re-isolated from the roots of wheat seedlings under salt stress. The relative water content in the leaves and roots, chlorophyll content, and root activity were significantly increased, and the accumulation of proline content in leaves was markedly accelerated with the plant growth parameters, but the content of leaf malondialdehyde under saline condition was significantly decreased. The antioxidant enzymes-superoxide dismutase (SOD), peroxidase (POD), and catalase (CAT) in wheat seedlings were increased by 29, 39, and 19%, respectively, with the application of the strain of T6 under salt stress; the relative expression of SOD, POD, and CAT genes in these wheat seedlings were significantly up-regulated. Our results indicated that the strain of T6 ameliorated the adverse effects significantly, protecting the seedlings from salt stress during their growth period. The possible mechanisms by which T6 suppresses the negative effect of NaCl stress on wheat seedling growth may be due to the improvement of the antioxidative defense system and gene expression in the stressed wheat plants.

Effect of drought stress on chlorophyll fluorescence, antioxidant enzyme activities and gene expression patterns in faba bean (Vicia faba L.)

ABSTRACTDrought is a major environmental stress that limits faba bean growth, leading to considerable reduction in their productivity. Two genotypes (Giza 3 and Hara) were evaluated under three water treatments (90%, 60% and 30% field capacity). The results showed that water stress affects negatively chlorophyll fluorescence parameters at different levels of water deficit and the variations of Fv/Fm, ΦPSII and electron transport rate in Giza 3 were largely higher than those in Hara. Drought preferentially enhanced the activities of superoxide dismutase, catalase and guaiacol peroxidase whereas it did not affect ascorbate peroxidase activity. Real-time reverse transcriptase-polymerase chain reaction results demonstrated that the expression of aquaporin (PIP), myeloblastosis (MYB), nine-cis-epoxycarotenoid dioxygenase, late embryogenesis abundant, dehydrins (Dhn), heat shock protein (HSP) and APETALA2/ethylene-responsive factor was modified in response to drought conditions and that all genes were differentially expressed in Hara and Giza 3. The observed expression patterns of these genes might be due to water deficit intensity according to cultivar’s tolerance to drought. Hara with the highest level of antioxidant enzyme activities, the accumulation of proline content and the expression level of Dhn, HSP and MYB gene throughout all conditions tested is reported more drought tolerant than Giza 3. This study should contribute to explaining the physiological, biochemical and molecular mechanism tolerance drought stress and improving breeding program in faba bean.

Exogenous application of brassinolide can alter morphological and physiological traits of Leymus chinensis (Trin.) Tzvelev under room and high temperatures

Plant growth regulating substances are involved in the physiological and metabolic processes of plants and enable them to cope with numerous environmental stresses. The effect of exogenously applied brassinolide (BR) with various concentrations (0.01, 0.1, and 1.0 mg L -1 ) was studied on morphological and physiological traits of Leymus chinensis (Trin.) Tzvelev under room and high temperatures in pots. The experimental results revealed that high temperature stress substantially perturbed growth, photosynthetic pigments, and root activity of L. chinensis; however, the deleterious effects of high temperature were partially ameliorated by the foliar application of BR. Compared to room temperature, high temperature stress decreased the plant height, leaf area, plant fresh and dry weight, chlorophyll a and b content, chlorophyll a/b ratio as well as root activity, while exacerbated the membrane damage as indicated by enhanced production of malondialdehyde (MDA). Accumulation of proline content, soluble protein and sugar content in L. chinensis improved by heat stress, compared with normal temperature; application of BR further improved their production thus aiding in the attainment of tolerance against heat stress. Elevated levels of antioxidant enzymes such as superoxide dismutase (SOD), peroxidase (POD), catalase (CAT), ascorbate peroxidase (APX), and glutathione reductase (GR) were observed under heat stress compared to room temperature, however, application of BR further proved beneficial in this regard. Our results indicated that BR could improve the growth and development of L. chinensis by enhancing the biosynthesis of photosynthetic pigments, osmolytes and antioxidant enzymes system in plants under both room and high temperature.

The impact of arbuscular mycorrhizal fungi in mitigating salt-induced adverse effects in sweet basil (Ocimum basilicum L.).

Salinity is one of the serious abiotic stresses adversely affecting the majority of arable lands worldwide, limiting the crop productivity of most of the economically important crops. Sweet basil (Osmium basilicum) plants were grown in a non-saline soil (EC = 0.64 dS m−1), in low saline soil (EC = 5 dS m−1), and in a high saline soil (EC = 10 dS m−1). There were differences between arbuscular mycorrhizal (Glomus deserticola) colonized plants (+AMF) and non-colonized plants (−AMF). Mycorrhiza mitigated the reduction of K, P and Ca uptake due to salinity. The balance between K/Na and between Ca/Na was improved in +AMF plants. Growth enhancement by mycorrhiza was independent from plant phosphorus content under high salinity levels. Different growth parameters, salt stress tolerance and accumulation of proline content were investigated, these results showed that the use of mycorrhizal inoculum (AMF) was able to enhance the productivity of sweet basil plants under salinity conditions. Mycorrhizal inoculation significantly increased chlorophyll content and water use efficiency under salinity stress. The sweet basil plants appeared to have high dependency on AMF which improved plant growth, photosynthetic efficiency, gas exchange and water use efficiency under salinity stress. In this study, there was evidence that colonization with AMF can alleviate the detrimental salinity stress influence on the growth and productivity of sweet basil plants.

Crescimento e conteúdo de prolina em plântulas de guandu submetidas a estresse osmótico e à putrescina exógena

O objetivo deste trabalho foi verificar o efeito da aplicação da poliamina putrescina no acúmulo de prolina e no crescimento inicial de plântulas de guandu cultivadas sob estresse hídrico ou salino, e avaliar se esta poliamina pode ser usada como atenuadora desses estresses. Sementes de duas cultivares de guandu, BRS Mandarim e Caqui, foram germinadas em caixas gerbox forradas com papel de filtro umedecido com 0,0, -0,2, -0,3, -0,4, -0,5 MPa de PEG 6000 ou 0, 20, 40, 60, 80 e 120 mmol L-1 de NaCl, na ausência (0 mmol L-1) ou na presença (0,5 mmol L-1) de putrescina. Utilizou-se o delineamento inteiramente casualizado, em arranjo fatorial 2x5x2 e 2x6x2 (duas cultivares, cinco níveis de deficiência hídrica ou seis níveis de estresse salino, e presença ou ausência de putrescina), com quatro repetições. O crescimento das plântulas é acentuadamente reduzido pelas condições de restrição hídrica e salinidade. A putrescina exógena incrementa, sob ambos os estresses, os teores de prolina nas plântulas de guandu, especialmente na cultivar BRS Mandarin, e atenua os efeitos da deficiência hídrica moderada nas cultivares estudadas. Os estresses de restrição hídrica e de salinidade causam acúmulo de prolina na parte aérea e nas raízes de ambas as cultivares. A prolina pode ser considerada um bom indicador bioquímico e fisiológico desses estresses em plântulas de guandu.

Effect of salinity stress on mycorrhizal association and growth response of peanut infected by Glomus mosseae

Arbuscular mycorrhiza is a mutualistic association between fungi and higher plants, and play a critical role in nutrient cycling and stress tolerance. However, much less is known about the mycorrhiza-mediated enhancement in growth and salinity tolerance of the peanuts (Arachis hypogaea L.) growing in the arid and semi-arid areas. Therefore, mycorrhizal status of Glomus mosseae in diverse salinity levels on original substrate soil conditions was investigated. Different growth parameters, accumulation of proline content and salt stress tolerance were studied. These investigations indicated that the arbuscular mycorrhizal fungi could improve growth of peanuts under salinity through enhanced nutrient absorption and photosynthesis. Chlorophyll content and leaf water content were increased significantly under salinity stress by the inoculation with mycorrhizal fungi. Tolerance of the plants to salinity was increased and the mycorrhizal association was found highly effective in enhancing peanut growth and establishment in soils under salinity and deficient in phosphorus.