CREA Journals (Consiglio per la ricerca in agricoltura e l’analisi dell’economia agraria)
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Genetic divergence, path coefficient, principal component and cluster analyses of maize genotypes in the mid-altitudes of Meghalaya
Get PDFA 2-year study was carried out on 84 maize genotypes to assess the genetic diversity for various morphological traits and their association with yield. There was a significant variation for all the traits studied among the genotypes. Moderate value of heritability and high genetic advance over mean were found for TLB infestation, average No of cobs per plant, average no of grains per plant and area under disease progress curve. Yield was found to be highly associated with other morphological traits. Average no of grains per plant have highest direct effect on yield (r = 0.831) followed by hundred grain weight (r = 0.386). Two major clusters comprising of 43 and 41 genotypes were formed. First 3 principal components having greater than one eigenvalues contributed 76.6% of total variation. FH-3358 and PRO-65 were found suitable for Meghalaya
Differential gene expression analysis of the Coix transcriptome under PEG stress
Get PDFDrought stress severely affects plant growth and crop yield. Coix lachryma-jobi L (Coix) commonly known as Job’s tears, is a member of the grass family in the tribe Maydeae. To understand the transcriptome dynamics and explore the important drought resistant genes during drought stress in coix seedlings, in this study,YiLiao 5, with good resistant drought was taken as the experimental material. The results showed 92,865 unigenes were detected and the average gene length was 737.85 bp, the N50 was 1,26bp. A comparison of the treatment and the control samples revealed that 1,128 differentially expressed genes (DEGs) were expressed, including 662 and 466 genes that were up-and down-regulated, respectively. According to the Gene Ontology (GO) database, among biological processes the metabolic process group was the largest group (14,908 genes, 24.28%) and contained high frequency of differentially expressed genes (352 genes, 24.22%). The DEGs are involved in 170 metabolic pathways. The plant hormone signal transduction and starch and sucrose metabolism were relatively obvious. Some DEGs and proteins were found, such as response to abscisic acid genes, 9-cis-epoxycarotenoid dioxygenase, some Transcription factors (TFs), protein serine/threonine phosphatase, late embryogenesis abundant protein (LEA). Eight genes analyzed by Quantitative Real-time PCR (qRT-PCR) confirmed the transcriptome results. Overall, this study had done the transcriptome sequencing and established a genomics database of Coix for the first time. Meanwhile the results also provided a molecular basis and theoretical resource for mechanistic studies on drought resistance in Coix
Qualitative, quantitative and molecular detection of aflatoxins from maize grains in north-west India
Get PDFThirty three isolates of Aspergillus flavus collected from different maize growing areas from Indian Punjab were screened for aflatoxin production using qualitative and quantitative methods. Qualitatively, bioassay on okra re- vealed 11 isolates to be positive for aflatoxin production with chlorosis index ranging from 0.14 to 0.33. The isolate Af 4 produced highest chlorosis index (1.33) thereby causing maximum reduction in germination of okra seedlings (20%). Concurrently, ammonia vapour test however, revealed 6 isolates positive for aflatoxin production, with one isolate Af 29 being highly toxigenic showing dark red colour development. In total, twelve isolates of A. flavus were observed to be positive using qualitative detection methods. These were further subjected to quantitative (HPLC) and molecular analysis. Out of these 12, eight isolates produced aflatoxin B (AFB ) in the range of 89 - 3269.2 µg kg-1, with highest concentration of AFB detected in Af 5 sample of Ludhiana district. These isolates were confirmed positive using aflatoxin gene specific primers OmtB, Omt1 and Nor1. Sequence analysis of the Nor1 gene amplified from six isolates with different levels of toxin production showed high homology among themselves. The amino acid sequence analysis showed that protein sequences were highly conserved with 99% similarity among them and with other strains in database
Marginal/peripheral populations of forest tree species and their conservation status: report for Atlantic region
Get PDFThis report is a synthesis of information from the national reports, prepared as part of the COST Action FP1202 Strengthening conservation: a key issue for adaptation of marginal/peripheral populations of forest trees to climate change in Europe (MaPFGR). The individual national reports can be found as part of the supplemental data to the COST action. The data compiled in this report indicate that the Atlantic area has sufficient resources in terms of knowledge and capacity to assess the potential impact of climate change on marginal and peripheral (MaP) sites within the area. Maps of vegetation, soil, climate and climatic predictions are publicly available for most countries and often are of high quality and resolution. These can be utilized to help identify MaP sites and populations in the Atlantic area. In addition, some species have been characterized genetically and the genetic data can also be utilized to identify and characterize sites. However, genetic data is not universally available and in particular may be absent for peripheral sites. There are many data sources for phenotypic traits, such as data from provenance trials but these have not been assessed for MaP populations. There may not be sufficient legislative capacity for the conservation of MaP populations in comparison to, for example, annex habitats of the EU Habitats Directive. Although some of the MaP sites lie within Natura 2000 boundaries, many are not in protected areas. If MaP populations are not characterized and conserved there is a risk of losing traits that may be of potential in adaptation to climate change. A detailed spatial analysis incorporating all of the data is needed to give a comprehensive assessment of the potential threats to MaP populations in this area
Artificial inoculation of maize seeds with Sporisorium reilianum f. sp. zeae
Get PDFThe objective of this research was to identify an inoculation method of Sporisorium reilianum f. sp. zeae, causal agent of the head smut of maize, which allows a high and consistent percentage of infection, for reliable selection of germplasm with genetic resistance to this pathogen. Seeds of the hybrid AZ 41801 were inoculated with telio-spores impregnated using as adherents: 1% (w/v) sodium carboxymethylcellulose (NaCMC) 1%, ADH®, 2% (w/v) sodium alginate 2%, 50% (w/v) brown sugar 50% (w/v), 2% (w/v) agar – agar, 10% (w/v) grenetin and a treatment 1: 200 (v/v) of inoculum: soil 1: 200 (v/v). Treated seeds were planted in a greenhouse in 40 x 40 cm polyethylene pots with sterile soil. In 2015, grenetin as adherent, induced 96.3% of diseased plants in greenhouse. Morphological and molecular characterization of the pathogen was carried out before the inoculation and after the finalevaluation. This method of inoculation was evaluated in 2016 in fieldconditions in Mixquiahuala, Hgo. A total of 160 lines C2-S3 from a bmaize population improvement program were inoculated with teliospores of S. reilianum f. sp. zeae using 10% grenetin as adherent. The incidence of the disease in both experiments planted in 2015 and 2016 was evalua-ted 45 days after flowering,with direct observation of symptoms and signs in male and female infloescences. One line showed 54.5% of infection. The hybrid AZ 41801 reached 70.7% of diseased plants. It is suggested to use 10% grenetin as adherent in the inoculation of maize seeds with teliospores of S. reilianum f. sp. zeae for the selection of disease resistant germplasm
Evaluation of physiological characteristics as selection criteria for drought tolerance in maize inbred lines and their hybrids
Get PDFImprovement for maize drought tolerance has always been a significantobjective for breeders and plant physiologists. Nowadays, climate change sets new challenges to major crop adaptation at stressful environments. For such a purpose, the measurement of physiological traits related to maize response to drought might prove to be useful indices. The objective of the present study was to establish whether the physiological traits can be used as reliable physiological markers to evaluate the performance of parental genotypes and their hybrids under both dry and normally watered conditions, and under two densities an ultra-low density (ULD) and a normal dense stand (DS). Thirty (30) maize inbred lines and 30 single-crosses among them were evaluated across three diverse locations in Greece. The ULD was 0.74 plants/m-2, while the DS comprised 4.44 plants m-2 in the water deficitregime, and 6.67 and 7.84 plants m-2 in the normal water treatment for lines and hybrids, respectively. There was a very good association between the physiological characteristics studied and grain yield under the ultra-low density and especially for inbred lines. It was shown that the physiological characteristics can facilitate the selection of stress-adaptive genotypes under the low-density conditions and may permit modern maize to be grown at a wider range of environments. At the normal densities such a possibility was not evidenced since physiological parameters and yield did not correlate for either parents or hybrid
SNP-based genetic diversity among few-branched-1 (Fbr1) maize lines and its relationship with heterosis, combining ability and grain yield of testcross hybrids
Get PDFSingle nucleotide polymorphism (SNP) markers are regarded as efficient,compared to other marker types in genetic characterization of maize (Zea mays L.) germplasm because of their vast coverage of the maize genome. The objectives of this study were to (a) genetically fingerprint few-branched-1’ (Fbr1) and normal tasselled CIMMYT elite lines using SNP markers, to assess their relatedness and level of homozygosity and (b) to determine SNP-based genetic distance among these maize lines and to find association of genetic distances with specific combining ability (SCA), mid-parent heterosis (MPH), high-parent heterosis (HPH) and mean grain yield of the hybrids. Twenty-six CIMMYT maize lines (12 with the Fbr1 gene, and 14 normal-tasselled) were genotyped using 1074 SNP marker loci. Fifteen of these lines were used in two separate diallel mating designs: a 9x9 and 6x6 crossing set-up, to make hybrids for yield evaluation. Average residual heterozygosity of SNP loci ranged from 0.2-36.1%, with an average of 8.2%, well above the expected ranges for residual heterozygosity found in maize inbred lines. The polymorphic information content (PIC) for the 1074 SNP loci ranged from 0.015-0.50, with an average of 0.25. Mean genetic distance for all pair wise comparisons of lines was lower (0.30) suggesting a high level of relatedness among lines. A number of elite CIMMYT lines were successfully converted to Fbr1, and were homozygous for the 1074 SNP loci, thus could be used in breeding programmes involving these new tassel mutants. The unweighted paired group method using arithmetic averages (UPGMA) cluster analysis revealed two discrete clusters for the inbred lines, reflecting heterotic groups used by CIMMYT. In the principal component (PC) analysis, PC1 and PC2 explained 10.87 and 9.08% respectively, of the molecular variance in tassel size for the 1074 SNPs. The results confirmed molecular markers as a powerful complement for use in genetic characterization, in assigning lines into defined heterotic groups and in examining the relationships among inbred lines at deoxyribonucleic acid (DNA) level. Marker-based genetic distances were positively correlated with hybrid performance, SCA and heterosis indicating that they could accurately predict hybrid performance in this set of germplasm. Grain yield for the hybrids ranged from 0.49-2.48 kg/plot, with an average of 1.80 kg/plot. Hybrids from closely related parental lines (according to SNP-based genetic distances) had the lowest mean grain yield, lowest SCA effects for grain yield, and had the lowest heterosis values. Thus, SNP-based genetic distance information would be useful for effective selection by avoiding genetically similar lines when selecting parents for breeding programmes that require genetically diverse lines as parents
Strategic selection of white maize inbred lines for tropical adaptation and their utilization in developing stable, medium to long duration maize hybrids
Get PDFWhite maize plays an important role in human diet, especially in traditional crop growing regions of northern hill region, north-eastern states and central-western parts of India. Breeding efforts to enhance the genetic potential of white maize was not so prominent as compared to yellow maize in the country. As a result, genetic base of the material utilized in white maize breeding program in India is very narrow and majorly contains indigenous germplasm and few introductions. Hence, efforts were made to use 365 white maize inbred lines from CIMMYT, Mexico, for breeding program. These new inbred lines were grown at winter nursery center, Indian Institute of Maize Research, New Delhi for its tropical adaptation. After preliminary evaluation, a total 47 inbred lines were selected and evaluated in randomized complete block design with two replications at Regional Maize Research and Seed Production Centre, Begusarai, Bihar, during rabi 2014. Out of this top performing 12 inbred lines viz, CML 47, CML 95, CML 314, CML 319, CML 377, CML 488, CML 494, CML 504, CML 517, CML 522, CML 531 and CML 538 were selected and were crossed in diallel manner to obtain 66 medium to long duration experimental hybrids. Stability analysis using AMMI model was done to identify adaptive hybrids with high yielding potentiality. According to the ASVi value obtained, the hybrid G38 appeared to be stable followed by G50 and G44. On the other hand, the hybrid G25 appeared as location specific hybrid suitable for high input conditions
Evaluating tropical single cross maize hybrids for adaptability and commercial value
Get PDFStability analysis was carried out to study stability in performance and genotype x environment interactions for sixty single cross hybrids along with three checks viz., 900M Gold, CP 818 and NK 6240 in three research farms of Foliage Crop Solutions Private Limited viz., Attur (Tamilnadu), Hosur (Tamilnadu), and Renebennur (Karnataka) un- der irrigated conditions during 2011-13. Data were recorded on different morphological and yield parameters viz., days to 50% silking, days to maturity, plant height, number of leaves, ear length, number of kernels row-1, number of kernels ear-1, hundred seed weight, and grain yield and the mean was used for statistical analysis. Analysis of variance carried out for all the characters revealed that the variance due to genotypes was highly significant for all the characters studied in all the three environments. Pooled analysis of variance for stability done using Eber- hart and Russel model of stability revealed that the variance due to genotypes, environments and environment components were highly significant for all the characters studied. However, it was found that the variance due to genotype x environment (linear) component was non-significant only for ear length and number of kernel rows and significant for the remaining characters
Genetic diversity, linkage disequilibrium and population structure among CIMMYT maize inbred lines, selected for heat tolerance study
Get PDFRising temperatures has led to reduced maize yields in tropical and sub tropical countries. This provides the necessity for identifying the diverse inbred lines that can produce high yielding hybrids under high temperature regimes. With this view, the present study was conducted to analyse the extent of genetic diversity and population structure among 64 CIMMYT maize inbred lines using SNP markers derived from GBS (Genotyping by sequencing) along with characterization of haplotype blocks and linkage disequilibrium. The average polymorphic information content (0.37) and gene diversity was very high (0.5) with mean kinship coefficients of 0.28 and genetic distance more than 0.4 between pair of two inbred lines. Clustering analysis based on ward’s method and euclid- ian distance showed presence of three sub groups. The population structure analysis using principle components showed three sub population. The average physical distance between pairs of markers was 27.7 kb with linkage disequilibrium (LD) estimation (r2) of 0.36 across all chromosomes, with rapid LD decay of 6.34 kb at r2 = 0.2. Haplotype analysis with 75,664 SNPs under confidence interval model revealed 616 haplotype blocks across all chromosomes with highest number of blocks on chromosome 5. The results clearly indicate the uniqueness of the majority of the inbred lines, which can contribute to new alleles in breeding programs for heat tolerance