Characterization Of Agronomic Traits Research Articles

Characterization of agronomic traits and genomic diversity in a newly assembled radish core collection

AbstractCrop breeding programs are reliant on the genetic diversity of varieties and germplasm collections. Raphanus sativus L. is a root crop species of the Brassicaceae family that accounts for ∼2% of global vegetable production. We recently reported the assembly of a new radish core collection consisting of 125 accessions obtained from worldwide germplasm banks. To develop a comprehensive plant resource for radish research and breeding, we characterized the agronomic traits of 83 accessions and analyzed their genome‐wide DNA variations along with 17 previously analyzed accessions. A total of 14 agronomically important root, leaf, and flower phenotypic traits were examined according to the guidelines of the International Union for the Protection of New Plant Varieties. Chemical diversity in radish roots was investigated by measuring their sugar, glucosinolate, and anthocyanin contents. Through high‐depth whole‐genome resequencing of 100 accessions and multi‐sample genotyping analysis using the Rs2.0 genome assembly as a reference, we identified a total of 796,294 homozygous high‐quality single‐nucleotide polymorphisms. Genetic structural analysis using a neighbor‐joining algorithm and multi‐dimensional scaling analysis of the variations were applied to classify the accessions into three major groups, including 37 and 55 accessions of European and Asian cultivated radishes, respectively, and eight wild radish accessions. For each accession, the mitochondria‐encoded Ogura cytoplasmic male‐sterility determinant orf138 and nuclear fertility restorer PPR‐B genes were reconstructed by reference‐guided assembly. It is anticipated that these genetic diversity and agronomic properties of the radish core collection will facilitate breeding programs to develop new radish cultivars with desirable profiles.

Construction of genetic linkage map and identification of QTLs related to agronomic traits in DH population of maize (Zea mays L.) using SSR markers.

In this study, we used phenotypic and genetic analysis to investigate Double haploid (DH) lines derived from normal corn parents (HF1 and 11S6169). DH technology offers an array of advantages in maize genetics and breeding as follows: first, it significantly shortens the breeding cycle by development of completely homozygous lines in two or three generations; and second, it simplifies logistics, including requiring less time, labor, and financial resources for developing new DH lines compared with the conventional RIL population development process. In our study, we constructed a maize genetic linkage map using SSR markers and a DH population derived from a cross of normal corn (HF1) and normal corn (11S6169). The DH population used in this study was developed by the following methods: we crossed normal corn (HF1) and normal corn (11S6169), which are parent lines of a normal corn cultivar, in 2014; and the next year, the F1 hybrids were crossed with a tropicalized haploid inducer line (TAIL), which is homozygous for the dominant marker gene R1-nj (Nanda and Chase in Crop Sci 6:213-215, 1966), and we harvested seeds of the haploid lines. A total of 200 SSR markers were assigned to 10 linkage groups that spanned 1145.4cM with an average genetic distance between markers of 5.7cM. 68 SSR markers showed Mendelian segregation ratios in the DH population at a 5% significance threshold. A total of 15 quantitative trait loci (QTLs) for plant height (PH), ear height (EH), ear height ratio (ER), leaf length (LL), ear length (EL), set ear length (SEL), set ear ratio (SER), ear width (EW), 100 kernel weight (100KW), and cob color (CC) were found in the 121 lines in the DH population. The results of this study may help to improve the detection and characterization of agronomic traits and provide great opportunities for maize breeders and researchers using a DH population in maize breeding programs.

Characterization of agronomic traits in a population of wheat derived from Triticum timopheevii and their association with Fusarium head blight

Fusarium head blight (FHB), caused mainly by Fusarium graminearum, is one of the most destructive diseases of wheat especially in humid and semi-humid wheat growing areas of the world. Agronomic traits such as plant height, flowering date, and presence/ absence of awns play important roles in wheat life cycle and grain yield. In the present study, characterization of agronomic traits and their association with Fusarium head blight were investigated in a population of recombinant inbred lines (RILs) derived from the cross of Canadian bread wheat cultivar ‘AC Brio’ to Triticum timopheevii-derived line ‘TC 67’. The population was grown under both greenhouse (Winnipeg, MB, Canada) and field (Carman and Glenlea, MB, Canada) conditions and measurements were made for agronomic traits including plant height, flowering date, presence/absence of awns, and glume threshability. The wheat genotypes were also assessed in the greenhouse for disease severity (type II resistance) and in field plots for disease incidence (type I resistance), disease severity (indicating a combination of type I and type II resistance), deoxynivalenol (DON) content (type III resistance), and Fusarium-damaged kernels (FDK) which is an indicator of type IV resistance. Results showed that there was significant variation in plant height, flowering date, and FHB resistance among the genotypes, and the frequency distributions of these traits were continuous, indicating the quantitative inheritance of the traits. While both plant height and flowering date showed negative correlations with disease incidence, severity, and DON content, they both were positively correlated with FDK under field conditions. In the greenhouse, both plant height and flowering date were positively correlated with disease severity. Awnedness and seed threshability were also significantly associated to all FHB-related traits. While the presence of awns was associated with a significant decrease in FHB, the genotypes that were easy to thresh were more susceptible to the disease. The line ‘TC 67’ with novel FHB resistance derived from T. timopheevii may be useful in wheat breeding, but the positive association of disease resistance with undesirable agronomic traits such as plant height may delay cultivar development efforts.

Identification of Low Phytic Acid in a Maize Inbred Line and Primary Screening of Its Molecular Markers

Reducing the content of phytic acid (PA, myo-inositol-1,2,3,4,5,6-hexakis phosphate) is important for improving the nutritional value of maize (Zea mays L.). The identification and application of low phytic acid (lpa) maize germplasm is an economical and effective approach in breeding program. In our previous study, Qi319 was identified as a low phytic acid inbred line. In this study, we found that the content of phytic acid phosphorus in Qi319 kernels is about one fourth of normal maize inbred lines based on quantitative analysis. The characterization of agronomic traits revealed that the germination rate of Qi319 was 75.5%, lower than that of normal inbred lines, however, Qi319 plants grew normally in the field. F2 population was generated by crossing between Qi319 and Lpa241, segregation was found for the content of phytic acid among F2 populations. The segregation ratio of 3:1 confirmed that the lpa trait was determined by a single recessive gene. We then identified two molecular markers (IDP7818 and IDP7635) located on the long arm of chromosome 2 that were co-segregated with low phytic acid loci. This result provides a fundamental basis for marker-assisted maize lpa selection process.

VARIABILITY OF STEM HEIGHT, GRAIN PER POD, THOUSAND-GRAIN MASS AND GRAIN SHAPE FOR SOME BEAN VARIETIES

ISHS International Symposium on Sustainable Use of Plant Biodiversity to Promote New Opportunities for Horticultural Production Development VARIABILITY OF STEM HEIGHT, GRAIN PER POD, THOUSAND-GRAIN MASS AND GRAIN SHAPE FOR SOME BEAN VARIETIES

Bean germplasm evaluation for anthracnose resistance and characterization of agronomic traits: A new physiological strain of Colletotrichum lindemuthianum infecting Phaseolus vulgaris L. in Spain

Reactions of 12 differential cultivars to 60 isolates of Colletotrichum lindemuthianum confirmed the presence of the gamma race in Asturias (North of Spain). In addition, one new race was identified as delta-mutant. The new binary nomenclature system identify the gamma race as race 38 and the delta-mutant race as race 7. A total of 40 germplasm lines which included 32 CIAT bean accessions and 8local bean varieties were evaluated for anthracnose resistance. Vegetative and reproductive adaptation of bean accessions was studied, as well as characterization for the presence of genes controlling expression of dwarfing. Results obtained reveal that14 bean genotypes showed good general adaptation and uniform resistance to anthracnose. Four bean lines resistant to anthracnose are carriers of DL genes. Resistant sources selected are quite diverse for plant type, seed color and seed size.

Characterization of agronomic traits and markers of recombinant inbred lines from intra- and interracial populations of Phaseolus vulgaris L.

The value of intra- and interracial populations in common bean (Phaseolus vulgaris L.) needs to be determined in order to create useful genetic variation for maximizing gains from selection, broadening the genetic base of commercial cultivars, and making efficient use of available resources. Five large-seeded parents of race Nueva Granada (N), two small-seeded race Mesoamerica (M), and one medium-seeded race Durango (D) were hybridized to produce one intraracial (N x N) and three interracial (two N x M and one N x D) populations. Seventy-nine F2-derived F6 lines randomly taken from each population along with their parents were evaluated for agronomic traits and markers at Palmira and Popayán, Colombia, in 1990 and 1991. Variation for agronomic traits and for morphological, protein, and isozyme markers was larger in interracial populations than in the intraracial population. Mean seed yield of all lines as well as yield of the highest yielding line from two interracial populations were significantly higher than that of the intraracial population. The highest (≥ 0.80±0.15) heritability was recorded for 100-seed weight. Values for seed yield varied from 0.19±0.17 to 0.50±0.16. Gains from selection (at 20% selection pressure) for seed yield ranged from 3.9% to 11.4%. Seed yield was positively associated with biomass yield, pods/m(2), and days to maturity, but harvest index showed negative correlations with these traits and a positive value with 100-seed weight. Polymorphism was recorded for phaseolin, lectins, protein Group-1 and protein Group-2 fractions, and six isozyme loci. Lines with indeterminate growth habit had significantly (P < 0.01) higher seed yield than lines with determinate growth habit in a Redkloud x MAM 4 population. Also, 23 other associations of markers with agronomic traits other than seed yield were recorded. Of these associations, lines with T phaseolin, the Diap1 (2) allele, and lilac flower color tended to possess greater seed weight.