Insights into Physiological, Biochemical and Molecular Responses in Wheat under Salt Stress

Globally, wheat is a major staple food crop that provides 20% of food calories for 30% of the human population. Wheat growth and production are significantly affected by salt stress at various stages and adversely affect germination, vegetative growth, stomatal conductance, photosynthesis, reproductive behavior, protein synthesis, enzymatic activity and finally hampered grain yield. Maintenance of low Na+/K+ ratio, antioxidants and hormonal regulation, and accumulation of compatible osmolytes such as glycine betaine, proline and trehalose help the wheat genotypes to mitigate the negative effects of salt stress. Recent studies have reported various mechanisms at the physiological, biochemical and molecular levels to adapt the salinity stress in various ecologies. Salt tolerant genotypes can be developed by conventional breeding approaches and through biotechnological approaches. This chapter reviews the updates on mechanisms and recent approaches to structure the salt-tolerant and high-yielding genotypes

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Not AvailableThe present study was explained about a direct and indirect regeneration protocol for an important wild medicinal plant Dioscorea deltoidea, a rich source of saponins and diosgenin. It was found that source of explant, basal medium composition, concentration of plant growth regulator and the photoperiod directly control morphogenetic responses. Out of all explants tested, only nodal segments performed better on the experimental growth media. Nodal segments initiated direct organogenesis when cultured on MS and RT (revised tobacco) medium supplemented with BAP and NAA or IBA. Growth medium supplemented with BAP (1.5 mg/l) and IBA (0.5 mg/l) induced maximum regeneration. Indirect roots regeneration was achieved on RT medium supplemented with IAA 1.0 mg/l and RT medium supplemented with BAP 1.0 mg/l and NAA 0.5 mg/l induced shoot regeneration through callus formed on MS medium containing 2, 4-D (2.0 mg/l).Not Availabl

Mycorrhizal symbiosis improved drought resistance in wheat using physiological traits

A two-year pot experiment was conducted to explore the potential of arbuscular mycorrhizal fungus (Glomus mosseae) symbiosis under drought stress on tolerant (WH 1025) and sensitive (WH 1105) wheat varieties. Drought stress was created by withholding (stop water irrigation) irrigation at jointing stage and heading stage in wheat. Mycorrhizal inoculation increased osmotic potential (ψs) of both the varieties at jointing and heading growth stages, respectively. Under drought condition, WH 1105 showed higher per cent reduction in RWC, chlorophyll content, and gas exchange traits (Pn, gS, and E) as compared to WH 1025 at both the growth stages. But, the mycorrhizal inoculation enhanced these traits in both varieties under control (irrigated) as well as drought stress condition. Higher decrease in Fv/Fm values was noted under drought stress, whereas the application of AMF resulted less reduction and the variety WH 1025 had more chlorophyll fluorescence than WH 1105 under mycorrhizal inoculation and stress treatments. It was also noticed that mycorrhizal colonization enhanced mean iWUE (Pn/E) by 3.6% in WH 1025 and 0.11% in WH 1105, respectively. In addition to the physiology traits, grain yield is the prime target under stress conditions and it was noted that mycorrhizal symbiosis gave beneficial results under control as well as stress conditions. AMF symbiosis significantly enhanced the drought tolerance index of both the wheat varieties. Correlation analysis further revalidates the beneficial role of AMF under stress condition and found that all physiological traits showed higher correlation with grain yield

Winter Tolerance Potential of Genetically Diverse Sugarcane Clones under Subtropical Climate of Northern India

The low temperature (LT) conditions that prevail during winter in subtropical regions of India drastically affect the growth and yield of sugarcane. To identify low-temperature-tolerant agronomical acceptable genotypes for immediate deployment as donor parents in the subtropical sugarcane breeding program, 34 sugarcane clones belonging to 7 genetically diverse groups were evaluated under three crop environments, viz., spring planting, winter ratoon and spring ratoon, during 2015–2016 and 2016–2017. In the winter ratoon crop, commercial cane sugar and cane yield were reduced, whereas sucrose % was increased over the spring planted crop and the spring ratoon crop. The wild species and introgressed hybrid groups showed improvement for yield and quality traits in the winter ratoon crop, whereas commercial and near commercial groups showed reduction for these traits over the plant and spring ratoon crops. The tropical cultivars group was the poorest performer irrespective of the traits and crops. Yield per se under a stress environment was adjudged as the best selection criteria. For classification of sugarcane clones according to their low temperature tolerance, an index named winter tolerance index (WTI) is proposed which takes into account the winter sprouting index (WSI), winter growth and yield per se of the winter ratoon crop. The WTI had significant positive association with WSI, cane yield, millable cane population and cane length. As per the WTI ratings, the wild species of Saccharum complex and introgressed hybrid groups were rated as excellent WT clones. Subtropical commercial or advanced generation groups were poor WT clones, and tropical commercial cultivars group were winter sensitive clones. Clones such as AS04-635, AS04-1687, IK76-48, GU07-2276, IND00-1040, IND00-1038 and IND00-1039 had excellent tolerance, and GU07-3849, AS04-245, Co 0238, AS04-2097 and GU07-3774 had good WTI scores. The variety, Co 0238, may be continued for cultivation under LT regions with prophylactic measurers for red rot, while other clones listed above may be utilized in subtropical breeding programs

In Silico Dissection of Regulatory Regions of PHT Genes from <i>Saccharum</i> spp. Hybrid and <i>Sorghum bicolor</i> and Expression Analysis of PHT Promoters under Osmotic Stress Conditions in Tobacco

Phosphorus (P) is the second-most essential macronutrient required for the growth and development of plants. It is involved in a number of cellular processes that contribute to the plant’s growth and development. This study investigated Saccharum spp. hybrid and Sorghum bicolor promoter regions of Phosphate transporters (PHT), viz., PHT1, PHT2, PHT3, PHT4, and PHO1, through in silico analysis. The transcription start sites (TSS), conserved motifs, and CpG islands were studied using various computational techniques. The distribution of TSSs indicated the highest promoter prediction scores (1.0). MSh2 and MSb4 were recognized as the common promoter motifs for PHT promoters, found in with 85 to 100% percentage of distribution. The CpG analysis revealed that the promoter regions of most PHT genes had low CpG density, indicating a possible tissue-specific expression. The PHT promoters were investigated for the presence of biotic- and abiotic-stress-associated transcription factor binding sites (TFbs) that revealed the presence of binding motifs for major transcription factors (TFs), namely, AP2/ERF, bHLH, bZIP, MYB, NAC, and WRKY. Therefore, the in-silico analysis of the promoter regions helps us to understand the regulation mechanism of phosphate transporter promoters and gene expression under stress management. The 5′ regulatory region of the EaPHT gene was isolated from Erianthus, a wild relative of the genus Saccharum. The promoter construct was prepared and transformed in tobacco wherein the promoter drove the expression of GUS. Analysis of GUS expression in transgenic tobacco revealed enhanced expression of GUS under salt-stress conditions. This is the first report of the isolation and characterization of a phosphate transporter gene promoter from Erianthus and is expected to be useful for the development of salt-stress transgenic crop plants

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Not AvailableThe present investigation was aimed to detect the specific polypeptide(s) appeared during the sequential stages of differentiation. Among different explants, only nodal explants showed good results for callusing. Depending on the fresh and dry weight, best callus growth was observed on MS medium supplemented with NAA (2.5 mg/L) in Dioscorea alata and 2, 4-D (2.0 mg/L) in D. deltoidea, respectively. This callus was used for the regeneration. Roots differentiation was observed on MS medium + NAA (2.0 mg/L) + IBA (0.5 mg/L) and shoots on MS medium + BAP (2.0 mg/L) + NAA (0.5 mg/L) in D. alata while in D. deltoidea, roots on RT medium + IAA (1.0 mg/L) and shoots on RT medium + BAP (1.0 mg/L) + NAA (0.5 mg/L). Continuous decrease was seen in the total soluble protein during the differentiation in D. alata whereas in D. deltoidea, the protein content decreased upto initiation stage. Four root specific polypeptides (MW 25.56, 24.35, 19.13 and 18.2 kDa) and three shoot specific polypeptides (MW 53.7, 25.12 and 19.13 kDa) were synthesized during the differentiation in D. alata. Similarly, two root specific (MW 33.9 and 31.69 kDa) and one shoot specific (MW 16.98 kDa) polypeptide band were appeared during differentiation in D.deltoidea.Not Availabl

Detection of Specific Polypeptide(s) Synthesized during the Sequential Stages of Differentiation in Dioscorea species

ABSTRACTThe present investigation was aimed to detect the specific polypeptide(s) appeared during the sequential stages of differentiation. Among different explants, only nodal explants showed good results for callusing. Depending on the fresh and dry weight, best callus growth was observed on MS medium supplemented with NAA (2.5 mg/L) inDioscorea alata and 2, 4-D (2.0 mg/L) inD. deltoidea, respectively. This callus was used for the regeneration. Roots differentiation was observed on MS medium + NAA (2.0 mg/L) + IBA (0.5 mg/L) and shoots on MS medium + BAP (2.0 mg/L) + NAA (0.5 mg/L) in D. alata while in D. deltoidea, roots on RT medium + IAA (1.0 mg/L) and shoots on RT medium + BAP (1.0 mg/L) + NAA (0.5 mg/L). Continuous decrease was seen in the total soluble protein during the differentiation inD. alatawhereas inD. deltoidea, the protein content decreased upto initiation stage. Four root specific polypeptides (MW 25.56, 24.35, 19.13 and 18.2 kDa) and three shoot specific polypeptides (MW 53.7, 25.12 and 19.13 kDa) were synthesized during the differentiation inD. alata. Similarly, two root specific (MW 33.9 and 31.69 kDa) and one shoot specific (MW 16.98 kDa) polypeptide band were appeared during differentiation in D. deltoidea

Selenium Mediated Alterations in Physiology of Wheat under Different Soil Moisture Levels

Soil moisture stress is one of the most serious aspects of climate change. Selenium (Se) is regarded as an essential element for animal health and has been demonstrated to protect plants from a number of abiotic challenges; however, our knowledge of Se-regulated mechanisms for enhancing crop yield is limited. We investigated the effects of exogenous Se supplementation on physiological processes that may impact wheat productivity during soil moisture stress. The plants were grown in plastic containers under screen-house conditions. The experiment was laid out in CRD consisting of three soil moisture regimes, i.e., control (soil moisture content of 12.5 &plusmn; 0.05%), moderate (soil moisture content of 8.5 &plusmn; 0.05%), and severe moisture stress (soil moisture content of 4.5 &plusmn; 0.05%). Selenium was supplied using sodium selenite (Na2SeO3) through soil application before sowing (10 ppm) and foliar application (20 ppm and 40 ppm) at two different growth stages. The foliar spray of Se was applied at the vegetative stage (70 days after planting) and was repeated 3 weeks later, whereas the control consisted of a water spray. The water status, photosynthetic efficiency, and yield were significantly decreased due to the soil&rsquo;s moisture stress. The exogenous Se application of 40 ppm resulted in decreased negative leaf water potential and improved relative water contents, photosynthetic rate, transpiration rate, and stomatal conductance in comparison to the control (without selenium) under water shortage conditions except the plants treated with soil application of selenium under severe moisture stress at 70 DAS. Subsequently, Se-regulated mechanisms improved 100 seed weight, biological yield, and seed yield per plant. We suggest that Se foliar spray (40 ppm) is a practical and affordable strategy to increase wheat output in arid and semi-arid regions of the world that are experiencing severe water shortages

Selenium Mediated Alterations in Physiology of Wheat under Different Soil Moisture Levels

Soil moisture stress is one of the most serious aspects of climate change. Selenium (Se) is regarded as an essential element for animal health and has been demonstrated to protect plants from a number of abiotic challenges; however, our knowledge of Se-regulated mechanisms for enhancing crop yield is limited. We investigated the effects of exogenous Se supplementation on physiological processes that may impact wheat productivity during soil moisture stress. The plants were grown in plastic containers under screen-house conditions. The experiment was laid out in CRD consisting of three soil moisture regimes, i.e., control (soil moisture content of 12.5 ± 0.05%), moderate (soil moisture content of 8.5 ± 0.05%), and severe moisture stress (soil moisture content of 4.5 ± 0.05%). Selenium was supplied using sodium selenite (Na2SeO3) through soil application before sowing (10 ppm) and foliar application (20 ppm and 40 ppm) at two different growth stages. The foliar spray of Se was applied at the vegetative stage (70 days after planting) and was repeated 3 weeks later, whereas the control consisted of a water spray. The water status, photosynthetic efficiency, and yield were significantly decreased due to the soil’s moisture stress. The exogenous Se application of 40 ppm resulted in decreased negative leaf water potential and improved relative water contents, photosynthetic rate, transpiration rate, and stomatal conductance in comparison to the control (without selenium) under water shortage conditions except the plants treated with soil application of selenium under severe moisture stress at 70 DAS. Subsequently, Se-regulated mechanisms improved 100 seed weight, biological yield, and seed yield per plant. We suggest that Se foliar spray (40 ppm) is a practical and affordable strategy to increase wheat output in arid and semi-arid regions of the world that are experiencing severe water shortages