Genetic Approaches to Enhance Multiple Stress Tolerance in Maize.
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ABSTRACT:
SUBMITTER: Malenica N
PROVIDER: S-EPMC8617808 | biostudies-literature |
REPOSITORIES: biostudies-literature
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Project description:Maize is a strategic food crop in sub-Saharan Africa. However, most maize growing tropical savannas particularly in West and Central African experience the occurrence of frequent droughts and Striga infestation, resulting in 30-100% yield losses. This production zones need maize cultivars that combine tolerance to the two stresses. IITA in collaboration with national partners has thus employed a sequential selection scheme to incorporate both drought tolerance and Striga resistance in topical maize hybrids using reliable screening protocols. The main objective of the present study was therefore to use grain yield and other agronomic traits recorded in regional collaborative hybrid trials conducted for 8 years under manged stressful and non-stressful conditions and across rainfed field environments to estimate genetic gains in grain yields using mixed model analyses. The results showed significant (p < 0.05) annual yield gains of 11.89 kg ha-1 under manged drought stress (MDS) and 86.60 kg ha-1 under Striga infestation (STRIN) with concomitant yield increases of 62.65 kg ha-1 under full irrigation (WW), 102.44 kg ha-1 under Striga non-infested (STRNO) conditions and 53.11 kg ha-1 across rainfed field environments. Grain yield displayed significant but not strong genetic correlation of 0.41 ± 0.07 between MDS and STRIN, indicating that gene expression was not consistent across the two stress conditions. Furthermore, grain yield recorded in MET had significant moderate genetic correlations of 0.58 ± 0.06 and 0.44 ± 0.07It with MDS and STRIN, respectively. These results emphasize the need to screen inbred linens under both stress conditions to further enhance the rate of genetic gain in grain yield in hybrids for areas where the two stresses co-occur. Nonetheless, this study demonstrated that the sequential selection scheme has been successful in generating hybrids with dependable yields that can reduce chronic food deficits in rural communities experiencing simultaneous presence of drought and S. hermonthica infestation in their production fields.
| S-EPMC9779929 | biostudies-literature
Project description:Globally, soil salinity has been on the rise owing to various factors that are both human and environmental. The abiotic stress caused by soil salinity has become one of the most damaging abiotic stresses faced by crop plants, resulting in significant yield losses. Salt stress induces physiological and morphological modifications in plants as a result of significant changes in gene expression patterns and signal transduction cascades. In this comprehensive review, with a major focus on recent advances in the field of plant molecular biology, we discuss several approaches to enhance salinity tolerance in plants comprising various classical and advanced genetic and genetic engineering approaches, genomics and genome editing technologies, and plant growth-promoting rhizobacteria (PGPR)-based approaches. Furthermore, based on recent advances in the field of epigenetics, we propose novel approaches to create and exploit heritable genome-wide epigenetic variation in crop plants to enhance salinity tolerance. Specifically, we describe the concepts and the underlying principles of epigenetic recombinant inbred lines (epiRILs) and other epigenetic variants and methods to generate them. The proposed epigenetic approaches also have the potential to create additional genetic variation by modulating meiotic crossover frequency.
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Project description:BackgroundDrought threatens the food supply of the world population. Dissecting the dynamic responses of plants to drought will be beneficial for breeding drought-tolerant crops, as the genetic controls of these responses remain largely unknown.ResultsHere we develop a high-throughput multiple optical phenotyping system to noninvasively phenotype 368 maize genotypes with or without drought stress over a course of 98 days, and collected multiple optical images, including color camera scanning, hyperspectral imaging, and X-ray computed tomography images. We develop high-throughput analysis pipelines to extract image-based traits (i-traits). Of these i-traits, 10,080 were effective and heritable indicators of maize external and internal drought responses. An i-trait-based genome-wide association study reveals 4322 significant locus-trait associations, representing 1529 quantitative trait loci (QTLs) and 2318 candidate genes, many that co-localize with previously reported maize drought responsive QTLs. Expression QTL (eQTL) analysis uncovers many local and distant regulatory variants that control the expression of the candidate genes. We use genetic mutation analysis to validate two new genes, ZmcPGM2 and ZmFAB1A, which regulate i-traits and drought tolerance. Moreover, the value of the candidate genes as drought-tolerant genetic markers is revealed by genome selection analysis, and 15 i-traits are identified as potential markers for maize drought tolerance breeding.ConclusionOur study demonstrates that combining high-throughput multiple optical phenotyping and GWAS is a novel and effective approach to dissect the genetic architecture of complex traits and clone drought-tolerance associated genes.
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Project description:Iron (Fe) is an essential trace element for almost all organisms and is often the major limiting nutrient for normal growth. Fe deficiency is a worldwide agricultural problem, which affects crop productivity and product quality. Understanding the Fe-deficiency response in plants is necessary for improving both plant health and the human diet. In this study, Fe-efficient (Ye478) and Fe-inefficient maize inbred lines (Wu312) were used to identify the genotypic difference in response to low Fe stress during different developmental stages and to further determine the optimal Fe-deficient Fe(II) supply level which leads to the largest phenotypic difference between Ye478 and Wu312. Then, genome-wide association analysis was performed to further identify candidate genes associated with the molecular mechanisms under different Fe nutritional statuses. Three candidate genes involved in Fe homeostasis of strategy II plants (strategy II genes) were identified, including ZmDMAS1, ZmNAAT1, and ZmYSL11. Furthermore, candidate genes ZmNAAT1, ZmDMAS1, and ZmYSL11 were induced in Fe-deficient roots and shoots, and the expression of ZmNAAT1 and ZmDMAS1 responded to Fe deficiency more in shoots than in roots. Beyond that, several genes that may participate in Fe homeostasis of strategy I plants (strategy I genes) were identified, which were either encoding Fe transporters (ZmIRT1 and ZmZIP4), or acting as essential ethylene signal transducers (ZmEBF1). Interestingly, ZmIRT1, ZmZIP4, and ZmEBF1 were significantly upregulated under low Fe stress, suggesting that these genes may be involved in Fe-deficiency tolerance in maize which is considered as strategy II plant. This study demonstrates the use of natural variation in the association population to identify important genes associated with Fe-deficiency tolerance and may further provide insights for understanding the molecular mechanism underlying the tolerance to Fe-deficiency stress in maize.
| S-EPMC9202619 | biostudies-literature
Project description:Soil amendments are known to promote several plant growth parameters. In many agro-ecosystems, water scarcity and drought induced phosphorus deficiency limits crop yield significantly. Considering the climate change scenario, drought and related stress factors will be even more severe endangering the global food security. Therefore, two parallel field trials were conducted to examine at what extent soil amendment of leonardite and humic acid would affect drought and phosphorus tolerance of maize. The treatments were: control (C: 100% A pan and 125?kg?P ha-1), P deficiency (phosphorus stress (PS): 62.5?kg?P ha-1), water deficit stress (water stress (WS): 67% A pan), and PS?+?WS (67% A pan and 62.5?kg?P ha-1). Three organic amendments were (i) no amendment, (ii) 625?kg?S?+?750?kg leonardite ha-1 and (iii) 1250?kg?S?+?37.5?kg humic acid ha-1) tested on stress treatments. Drought and P deficiency reduced plant biomass, grain yield, chlorophyll content, Fv/Fm, RWC and antioxidant activity (superoxide dismutase, peroxidase, and catalase), but increased electrolyte leakage and leaf H2O2 in maize plants. The combined stress of drought and P deficiency decreased further related plant traits. Humic acid and leonardite enhanced leaf P and yield in maize plants under PS. A significant increase in related parameters was observed with humic acid and leonardite under WS. The largest increase in yield and plant traits in relation to humic acid and leonardite application was observed under combined stress situation. The use of sulfur-enriched amendments can be used effectively to maintain yield of maize crop in water limited calcareous soils.
| S-EPMC7156716 | biostudies-literature
Project description:Saline stress is one of the abiotic stresses that most compromises the yield of crops and can be mitigated by plant growth-promoting rhizobacteria (PGPR). This work characterized rhizobacteria isolates from the genus Streptomyces as PGPR and evaluated their role on growth and alleviation of the effects caused by saline stress in maize (Zea mays L.). Production of indolic compounds (IC), siderophores, ACC deaminase, phenazines, and promotion of plant growth were determined to characterize bacterial isolates. Salinity tolerance was accessed by culturing the Streptomyces isolates under NaCl increasing concentrations (0-300 mM). Four Streptomyces isolates exhibiting PGPR traits and salinity tolerance were selected and their effect on tolerance of maize plants to saline stress was evaluated. Plants obtained from bacterized seeds and submitted to 100 and 300 mM NaCl were used. All Streptomyces spp. produced IC and siderophores, CLV178 being the best producer of these two compounds. ACC deaminase was detected in six of the 10 isolates (CLV95, CLV97, CLV127, CLV179, CLV193, and CLV205), while phenazines were found only in CLV186 and CLV194. All isolates were tolerant to salinity, growing at concentrations up to 300 mM NaCl, with exception of CLV188. Increased concentrations of IC were detected in most of the isolates exposed to salinity. CLV97 and CLV179 significantly promoted growth of roots and leaves of maize plants and attenuated the negative effects of salinity on plant growth. Root colonization by Streptomyces spp. was confirmed in plants cultivated 20 days under saline stress.
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Project description:Soybean production is greatly influenced by abiotic stresses imposed by environmental factors such as drought, water submergence, salt, and heavy metals. A thorough understanding of plant response to abiotic stress at the molecular level is a prerequisite for its effective management. The molecular mechanism of stress tolerance is complex and requires information at the omic level to understand it effectively. In this regard, enormous progress has been made in the omics field in the areas of genomics, transcriptomics, and proteomics. The emerging field of ionomics is also being employed for investigating abiotic stress tolerance in soybean. Omic approaches generate a huge amount of data, and adequate advancements in computational tools have been achieved for effective analysis. However, the integration of omic-scale information to address complex genetics and physiological questions is still a challenge. In this review, we have described advances in omic tools in the view of conventional and modern approaches being used to dissect abiotic stress tolerance in soybean. Emphasis was given to approaches such as quantitative trait loci (QTL) mapping, genome-wide association studies (GWAS), and genomic selection (GS). Comparative genomics and candidate gene approaches are also discussed considering identification of potential genomic loci, genes, and biochemical pathways involved in stress tolerance mechanism in soybean. This review also provides a comprehensive catalog of available online omic resources for soybean and its effective utilization. We have also addressed the significance of phenomics in the integrated approaches and recognized high-throughput multi-dimensional phenotyping as a major limiting factor for the improvement of abiotic stress tolerance in soybean.
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Project description:The relationship between Mg-protoporphyrin IX (Mg-Proto IX) signals and plant's tolerance to cold stress is investigated. Arabidopsis seedlings grown for 3 weeks were pretreated with 2 mM glutamate (Glu) and 2 mM MgCl2 for 48 h at room temperature to induce Mg-Proto IX accumulation. Then cold stress was performed at 4°C for additional 72 h. Glu + MgCl2 pre-treatments alleviated the subsequent cold stress significantly by rising the leaf temperature through inducing Mg-Proto IX signals. The protective role of Glu + MgCl2 treatment was greatly compromised in the mutants of Mg-Proto IX synthesis, Mg-Proto IX signaling, and cyanide-resistant respiration. And the enhancement of cold-responsive gene expression was greatly compromised in the mutants of Mg-Proto IX synthesis, Mg-Proto IX signaling and ABA signaling, but not in the mutant of cyanide-resistant respiration. Cold stress promoted cyanide-resistant respiration and leaf total respiration exponentially, which could be further induced by the Glu + MgCl2 treatment. Mg-Proto IX signals also activate antioxidant enzymes and increase non-enzymatic antioxidants [glutathione but not ascorbic acid (AsA)] to maintain redox equilibrium during the cold stress.
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Project description:Climate change is expected to aggravate the effects of drought, heat and combined drought and heat stresses. An important step in developing 'climate smart' maize varieties is to identify germplasm with good levels of tolerance to the abiotic stresses. The primary objective of this study was to identify landraces with combined high yield potential and desirable secondary traits under drought, heat and combined drought and heat stresses. Thirty-three landraces from Burkina Faso (6), Ghana (6) and Togo (21), and three drought-tolerant populations/varieties from the Maize Improvement Program at the International Institute of Tropical Agriculture were evaluated under three conditions, namely managed drought stress, heat stress and combined drought and heat stress, with optimal growing conditions as control, for two years. The phenotypic and genetic correlations between grain yield of the different treatments were very weak, suggesting the presence of independent genetic control of yield to these stresses. However, grain yield under heat and combined drought and heat stresses were highly and positively correlated, indicating that heat-tolerant genotypes would most likely tolerate combined drought and stress. Yield reduction averaged 46% under managed drought stress, 55% under heat stress, and 66% under combined drought and heat stress, which reflected hypo-additive effect of drought and heat stress on grain yield of the maize accessions. Accession GH-3505 was highly tolerant to drought, while GH-4859 and TZm-1353 were tolerant to the three stresses. These landrace accessions can be invaluable sources of genes/alleles for breeding for adaptation of maize to climate change.
| S-EPMC6918211 | biostudies-literature
Project description:The present study aimed to witness the plant-microbe interaction associated with salt tolerance in crops. We isolated the endophytic microbe from the root zone of halophytic grass. Later, the salt tolerance of the endophyte was tested in the saline medium and was identified using nucleotide sequencing (GenBank under the accession numbers: SUB9030920 AH1_AHK_ITS1 MW570850: SUB9030920 AH1_AHK_ITS4 MW570851). Rice and maize seeds were coated with identified endophyte Aspergillus terreus and were sown in separate plastic pots. Later 21-day-old seedlings were subjected to three NaCl concentrations, including 50, 100, and 150 mM salt stress. Under saline conditions, A. terreus showed a substantial increase in growth, biomass, relative water content, oxidative balance, and photochemical efficiency of rice and maize plants. The data reflected that the stimulation of gibberellic acid (GA) in treated leaves may be the main reason for the upregulation of photosynthesis and the antioxidant defense cascade. The data also depict the downregulation of oxidative damage markers malondialdehyde, hydrogen peroxide in rice and maize plants. Conclusively, salt-tolerant endophytic fungus A. terreus explicitly displayed the positive plant-microbe interaction by developing salt tolerance in rice and maize plants. Salt tolerance by endophytic fungus coincides with the enhanced GA concentration, which illustrated the stimulated physiological mechanism and gene in response to the extreme environmental crisis, resulting in improved crop productivity.
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