Plants are recurrently exposed to myriads of biotic and abiotic stresses leading to several bioch... more Plants are recurrently exposed to myriads of biotic and abiotic stresses leading to several biochemical and physiological variations that cause severe impacts on plant growth and survival. To overcome these challenges, plants activate two primary defense mechanisms, such as structural response (cell wall strengthening and waxy epidermal cuticle development) and metabolic changes, including the synthesis of anti-microbial compounds and proteins, especially the pathogenesis-related (PR) proteins. PR proteins are members of a super large family of defense proteins that exhibit antimicrobial activities. Their over-expression in plants provides tolerance to many abiotic and biotic stresses. PR proteins have been classified into 17 families, including PR-5-also called thaumatin-like proteins (TLPs) that involve osmotin and osmotin-like proteins (OLPs). Osmotin was first identified in tobacco (Nicotiana tabacum var. Wisconsin 38), and then its homolog proteins (OLPs) were reported from the whole plant kingdom. Osmotin and OLPs are ubiquitous in all fruits and vegetables. Their expression has been detected in various plant tissues and organs. The phylogenetic tree studies revealed that the osmotin group originated from spermatophytes. Moreover, the atomic structure of OLP has shown similarity to thaumatin and TLPs from monocot and eudicot species, which determines a strong evolutionary pressure in flowering plants for conserving thaumatin fold. This is associated with the role of these proteins against pathogens as defense molecules and to induce stress tolerance to plants against several biotic and abiotic factors. In this review, we have briefly described the development history of osmotin, including its function and mechanism to induce biotic and abiotic stress tolerance to plants.
Drought is major abiotic stress affecting the morphological, physiological and biochemical proces... more Drought is major abiotic stress affecting the morphological, physiological and biochemical processes. Genetic improvement for drought tolerance in wheat could be possible to develop new genotypes through conventional breeding. To investigate drought resistance under water stress condition, a trial was conducted in spilt block design, using eight genotypes, i.e., Inqlab-91, PBGST-03, PBGST-01, PBGST-02, SKD-1, Hero, Sundar, and Sassuai along with two treatments (non-stress and water stress at anthesis stage). The experiment was carried out inthe field of Botanical Garden, Sindh Agriculture University, Tandojam, Sindh, Pakistan. A significant reduction appeared in morphological traits at the anthesis stage due to the reduction of irrigation. The mean squares from analysis of variance due to genotypes, treatment, and treatments x genotypes interactions were significant at P ≤ 0.05 for all the traits, indicating that the genotypes performed variably under stress conditions. Based on the mean performance, among the cultivars; Sassui revealed better performance for grains spike-1 and seed index (1000gwt) under normal irrigations, whereas under stress at anthesis, PBGST-02 showed higher grain yield plant-1 , maximum productive tillers, and spikelets spike-1. Hence, such genotypes could be suggested to be tolerant under water stress.The correlation coefficient showed that spike length, spikelets spike-1 and grains spike 1 possessed positive and significant association with grain yield plant-1 at normal conditions. Seed index (1000gwt.) and harvest index (%) exhibited a positive but non-significant correlation. However, these all traits revealed a positive significant association under stress conditions with grain yield plant-1. Based on these results, the genotypes PBGST-03, Sassuai and SKD-1 are the potential genotypes that could be used in the water-deficient condition.
Plants are prone to a number of pathogens and abiotic stresses that cause various disorders. Howe... more Plants are prone to a number of pathogens and abiotic stresses that cause various disorders. However, plants possess a defense mechanism to cope with these stresses. The osmotin protein belongs to the PR-5 family of Pathogenesis-related (PR) proteins, which are produced in response to diseases caused by various biotic and abiotic stresses. Osmotin uses a signal transduction pathway to inhibit the activity of defensive cell wall barriers and increases its own cytotoxic efficiency. However, in response to cytotoxic effects, this pathway stimulates a mitogen-activated protein kinase (MAPK) cascade that triggers changes in the cell wall and enables osmotin's entrance into the plasma membrane. This mechanism involves cell wall binding and membrane perturbation, although the complete mechanism of osmotin activity has not been fully elucidated. Osmotin possesses an acidic cleft that is responsible for communication with its receptor in the plasma membrane of fungi. Osmotin is also involved in the initiation of apoptosis and programmed cell death, whereas its overexpression causes the accumulation of proline in transgenic plants. A higher concentration of osmotin can cause the lysis of hyphae tips. This review highlights the role of osmotin protein in the plant defense mechanism and its mode of action against numerous pathogens in wild and transgenic plants.
Wheat (Triticum aestivum L.) and maize (Zea mays L.) are important cereal crops grown worldwide. ... more Wheat (Triticum aestivum L.) and maize (Zea mays L.) are important cereal crops grown worldwide. In Pakistan, various varieties of wheat and maize are grown and a number of biotic and abiotic factors influence its production. These are mainly used as a food source and raw material for animal feed. Bipolaris sorokiniana is a hemibiotrophic phytopathogenic fungus that affects various grass species and causes number of diseases on small grains. An investigation was undertaken to evaluate the comparative expression of pathogenesis-related protein genes in wheat and maize under B. sorokiniana stress. After stress, these crops showed disease resistance by improving biochemical parameters like proline, protein, sugar and chlorophyll content. Morpho-physiological parameters including shoot length, root length, relative water content and fresh as well as dry weight were affected by fungal stress. Expression analysis of PR-proteins in stressed plants of wheat confirmed their role in plant defence. PR-1, Thaumatin-like protein (TLP), and β 1,3 glucanase were highly expressed under stress in wheat variety (RWP13), it suggests the role of these genes in the prescribed variety. These genes did not show their expression in susceptible wheat variety (SWG13). Zm PR-5 and Zm 1,3 β-glucanase were highly expressed in maize variety (RMN27) after stress which suggests their role in defence mechanism of this variety. While on the other hand, no significant expression of these genes was observed in susceptible maize variety (SMIG). In future, these genes can be over-expressed in transgenic plants to make them resistant against a number of biotic and abiotic factors.
Plants are recurrently exposed to myriads of biotic and abiotic stresses leading to several bioch... more Plants are recurrently exposed to myriads of biotic and abiotic stresses leading to several biochemical and physiological variations that cause severe impacts on plant growth and survival. To overcome these challenges, plants activate two primary defense mechanisms, such as structural response (cell wall strengthening and waxy epidermal cuticle development) and metabolic changes, including the synthesis of anti-microbial compounds and proteins, especially the pathogenesis-related (PR) proteins. PR proteins are members of a super large family of defense proteins that exhibit antimicrobial activities. Their over-expression in plants provides tolerance to many abiotic and biotic stresses. PR proteins have been classified into 17 families, including PR-5-also called thaumatin-like proteins (TLPs) that involve osmotin and osmotin-like proteins (OLPs). Osmotin was first identified in tobacco (Nicotiana tabacum var. Wisconsin 38), and then its homolog proteins (OLPs) were reported from the whole plant kingdom. Osmotin and OLPs are ubiquitous in all fruits and vegetables. Their expression has been detected in various plant tissues and organs. The phylogenetic tree studies revealed that the osmotin group originated from spermatophytes. Moreover, the atomic structure of OLP has shown similarity to thaumatin and TLPs from monocot and eudicot species, which determines a strong evolutionary pressure in flowering plants for conserving thaumatin fold. This is associated with the role of these proteins against pathogens as defense molecules and to induce stress tolerance to plants against several biotic and abiotic factors. In this review, we have briefly described the development history of osmotin, including its function and mechanism to induce biotic and abiotic stress tolerance to plants.
Drought is major abiotic stress affecting the morphological, physiological and biochemical proces... more Drought is major abiotic stress affecting the morphological, physiological and biochemical processes. Genetic improvement for drought tolerance in wheat could be possible to develop new genotypes through conventional breeding. To investigate drought resistance under water stress condition, a trial was conducted in spilt block design, using eight genotypes, i.e., Inqlab-91, PBGST-03, PBGST-01, PBGST-02, SKD-1, Hero, Sundar, and Sassuai along with two treatments (non-stress and water stress at anthesis stage). The experiment was carried out inthe field of Botanical Garden, Sindh Agriculture University, Tandojam, Sindh, Pakistan. A significant reduction appeared in morphological traits at the anthesis stage due to the reduction of irrigation. The mean squares from analysis of variance due to genotypes, treatment, and treatments x genotypes interactions were significant at P ≤ 0.05 for all the traits, indicating that the genotypes performed variably under stress conditions. Based on the mean performance, among the cultivars; Sassui revealed better performance for grains spike-1 and seed index (1000gwt) under normal irrigations, whereas under stress at anthesis, PBGST-02 showed higher grain yield plant-1 , maximum productive tillers, and spikelets spike-1. Hence, such genotypes could be suggested to be tolerant under water stress.The correlation coefficient showed that spike length, spikelets spike-1 and grains spike 1 possessed positive and significant association with grain yield plant-1 at normal conditions. Seed index (1000gwt.) and harvest index (%) exhibited a positive but non-significant correlation. However, these all traits revealed a positive significant association under stress conditions with grain yield plant-1. Based on these results, the genotypes PBGST-03, Sassuai and SKD-1 are the potential genotypes that could be used in the water-deficient condition.
Plants are prone to a number of pathogens and abiotic stresses that cause various disorders. Howe... more Plants are prone to a number of pathogens and abiotic stresses that cause various disorders. However, plants possess a defense mechanism to cope with these stresses. The osmotin protein belongs to the PR-5 family of Pathogenesis-related (PR) proteins, which are produced in response to diseases caused by various biotic and abiotic stresses. Osmotin uses a signal transduction pathway to inhibit the activity of defensive cell wall barriers and increases its own cytotoxic efficiency. However, in response to cytotoxic effects, this pathway stimulates a mitogen-activated protein kinase (MAPK) cascade that triggers changes in the cell wall and enables osmotin's entrance into the plasma membrane. This mechanism involves cell wall binding and membrane perturbation, although the complete mechanism of osmotin activity has not been fully elucidated. Osmotin possesses an acidic cleft that is responsible for communication with its receptor in the plasma membrane of fungi. Osmotin is also involved in the initiation of apoptosis and programmed cell death, whereas its overexpression causes the accumulation of proline in transgenic plants. A higher concentration of osmotin can cause the lysis of hyphae tips. This review highlights the role of osmotin protein in the plant defense mechanism and its mode of action against numerous pathogens in wild and transgenic plants.
Wheat (Triticum aestivum L.) and maize (Zea mays L.) are important cereal crops grown worldwide. ... more Wheat (Triticum aestivum L.) and maize (Zea mays L.) are important cereal crops grown worldwide. In Pakistan, various varieties of wheat and maize are grown and a number of biotic and abiotic factors influence its production. These are mainly used as a food source and raw material for animal feed. Bipolaris sorokiniana is a hemibiotrophic phytopathogenic fungus that affects various grass species and causes number of diseases on small grains. An investigation was undertaken to evaluate the comparative expression of pathogenesis-related protein genes in wheat and maize under B. sorokiniana stress. After stress, these crops showed disease resistance by improving biochemical parameters like proline, protein, sugar and chlorophyll content. Morpho-physiological parameters including shoot length, root length, relative water content and fresh as well as dry weight were affected by fungal stress. Expression analysis of PR-proteins in stressed plants of wheat confirmed their role in plant defence. PR-1, Thaumatin-like protein (TLP), and β 1,3 glucanase were highly expressed under stress in wheat variety (RWP13), it suggests the role of these genes in the prescribed variety. These genes did not show their expression in susceptible wheat variety (SWG13). Zm PR-5 and Zm 1,3 β-glucanase were highly expressed in maize variety (RMN27) after stress which suggests their role in defence mechanism of this variety. While on the other hand, no significant expression of these genes was observed in susceptible maize variety (SMIG). In future, these genes can be over-expressed in transgenic plants to make them resistant against a number of biotic and abiotic factors.
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