Genetic diversity studies on selected rice varieties grown in Africa based on aroma, cooking and eating quality

Rice grain quality is an important factor that has a great influence on its market value and consumer acceptance. It is determined by three parameters controlling the cooking and eating qualities of rice (amylose content, gelatinization temperature and gel consistency) and by the aroma, which becomes a criterion increasingly preferred by consumers. Molecular characterization of specific genomic regions of rice genotypes by trait specific markers can help in the development of suitable breeding program. This study was conducted at AfricaRice Regional station, Saint-Louis, Senegal. 30 rice genotypes commonly used in Africa were evaluated using eight simple sequence repeat (SSR) markers linked to the cooking, eating properties, and the aroma. The total number of alleles was 45 with an average of 5.63 allele per locus. The number of alleles per marker varied from three for RM204 to eight for RM190 and RM342A and the effective number of alleles varied from 1.66 for RM204 to 6.16 for RM342A. The polymorphic information content (PIC) varied from 0.39 to 0.83 and the allele frequency ranged from 0.015 to 0.75. A maximum genetic similarity of 1 was observed between Gambiaka Kokoum and Gambiaka Burkina Faso, Basmati 270 and Basmati 370, Sahel 108 and Sahel 201, Sahel 108 and Sahel 208, Sahel 201 and Sahel 208, Sahel 202 and Sahel 209, and Sahel 305 and Sahel 317. The Sahel varieties found with maximum genetic similarity have the same amylose content, but different gelatinization temperature except Sahel 305 and Sahel 317 which have the same cooking and eating properties. Therefore, more markers are needed to discriminate those varieties. Minimum genetic similarity was observed between traditional aromatic rice Basmati 370 and the landrace Gambiaka Nigeria. The unweighted pair-groups method using arithmetic averages (UPGMA) cluster analysis of these cultivars enabled the classification of our varieties in five major groups with additional subclusters in groups 2, 3 and 4. Groups 1 and 2 composed of aromatics varieties, group 3 gathered the three improved Sahel aromatic varieties, group 4 was the most diversified group with three sub-clusters and group 5 corresponded to the traditional varieties Gambiaka. The results of this study indicated that the use of trait specific SSR markers enabled to group the varieties according to their cooking and eating quality and the aroma and therefore can be very useful in breeding rice varieties harboring good cooking and eating quality traits and aroma in rice breeding program.Keywords: Grain quality, cooking and eating properties, aroma, cluster analysis, simple sequence repeat (SSR), ric

CHEMICAL FERTILITY OF GARDEN SOILS IN SOUTH TOGO: ANALYSIS, CORRELATIONS AND REASONED PROPOSAL OF FERTILIZERS RATE FOR EFFICIENT PRODUCTION OF SPINACIA OLERACEA L.

In this study, a sample of 12 garden soils were analyzed and compared to quality standards. A reasoned fertilization method was developed using online software "Fertilizer Rate Calculator". Results indicate that among macronutrients, those of potassium are very high and even tend to exceed standard. Moreover, 92% of soils studied are poor in nitrogen, 8% in phosphorus, 0% in potassium and 25% in organic matter. In  a reasoned fertilization method developed for spinach production,  800 Kg/Ha and 567 Kg/Ha of NPK have been proposed for sustainable production of this vegetable on soils poor in nitrogen and phosphorus while a mixing of NPK 15-15-15 (340 Kg/ha) and compost 173-313-1328 (4000 T/Ha) would be suitable for soils poor in nitrogen and organic matter. The study of correlations between the different parameters through PCA allows to conclude that contents of total and available nutrients in soils are independent of organic matter, pH and particle size. Contrary, those of total organic matter and the pH would be the most impacted by the particle size types. This aspect earns to be considered in any fertilization processes of soils to prevent elevation of C/N ratio and consequently hunger of nitrogen in these soils. These results may contribute to future soil’s chemicals changes model and suitable fertilization methods development

Association Analysis of Salt Tolerance in Asiatic cotton (<em>Gossypium arboretum</em>) with SNP Markers

Salinity is not only a major environmental factor which limits plant growth and productivity, but it has also become a worldwide problem. However, little is known about the genetic basis underlying salt tolerance in cotton. This study was carried out to identify marker-trait association signals of seven salt-tolerance-related traits and one salt tolerance index using association analysis for 215 accessions of Asiatic cotton. According to a comprehensive index of salt tolerance (CIST), 215 accessions were mainly categorized into four groups, and 11 accessions with high salinity tolerance were selected for breeding. Genome-wide association studies (GWAS) revealed nine SNP rich regions significantly associated with relative fresh weight (RFW), relative stem length (RSL), relative water content (RWC) and CIST. The nine SNP rich regions analysis revealed 143 polymorphisms that distributed 40 candidate genes and significantly associated with salt tolerance. Notably, two SNP rich regions on chromosome 7 were found to be significantly associated with two salinity related traits, RFW and RSL, by the threshold of −log10P ≥ 6.0, and two candidate genes (Cotton_A_37775 and Cotton_A_35901) related to two key SNPs (Ca7_33607751 and Ca7_77004962) were possibly associated with salt tolerance in G. arboreum. These can provide fundamental information which will be useful for future molecular breeding of cotton, in order to release novel salt tolerant cultivars

Stable QTLs for fiber length, fiber micronaire and fiber strength identified in the RILs.

<p>Stable QTLs for fiber length, fiber micronaire and fiber strength identified in the RILs.</p

Expressions of candidate genes Gh_D06G0694, Gh_D06G0721, Gh_D06G0740 and Gh_D06G1025.

<p>a: Expression of Gh_D06G0694; b: Expression of Gh_D06G0721; c: Expression of Gh_D06G0740; d: Expression of Gh_D06G1025.</p

Collinearity of marker positions in the genetic and physical maps using the genome of a: <i>Gossypium hirsutum</i>; and b: <i>Gossypium raimondii</i>.

<p>Collinearity of marker positions in the genetic and physical maps using the genome of a: <i>Gossypium hirsutum</i>; and b: <i>Gossypium raimondii</i>.</p