Grain morphological characterization and protein content of sixty-eight local rice (Oryza sativa L) cultivars from Cameroon

Rice (Oryza sativa L.) cultivated in Cameroon is appreciated by consumers for its nutritive quality and good taste. Diversity of 68 local rice cultivars was investigated via grain morphology and protein content characterization. The size and shape of grains were determined and used with yield parameters to classify the cultivars and perform Principal Component Analysis (PCA). Total protein content and glutelin content of eight selected cultivars (CMRGNd, CMRGDn, CMRGTï, CMRTBa, CMRDWb, CMRDTc3, CMRDTx5 and CMRDTx6) were evaluated by Bradford assay and correlation analysis of all the parameters studied was performed. Long size grains (42) were predominant over extra-long (16), medium (9) and short (1) grains. Slender shaped grains (36) were distinguished as well as medium (28) and bold (4) grains. The 68 cultivars were grouped into four clusters independent of their origins. PCA revealed three principal components accounting for 74.4% of total variation. Highest total protein content was observed in CMRGNd (14.3%) and highest glutelin content in CMRGDn (10.1 mgEqvBSA/g DW). Pearson correlation of the different variables revealed no significant correlation between total protein and glutelin contents with the agro-morphological parameters evaluated in this study. This suggests that none of these parameters could be descriptor for protein content. Positive correlation between grain length and yield (r = 0.7) suggests grain length as yield descriptor

Application of heat-treated oyster shell powder to induce priming of Theobroma cocoa seedlings plant defense system against Phytophthora megakarya attack

Priming with natural compounds is an interesting alternative for sustainable agriculture to explore the molecular mechanisms associated with the management of diseases caused by soil borne pathogens. The aim of this work was to evaluate the effect of the soil amendment with bio-oyster shell on the stimulation of the cocoa plant defense systems against P. megakarya in the nursery. For this purpose, the potential of bio-oyster shell to stimulate cocoa plant defense mechanisms was evaluated by soil amendment at 1% W/W under greenhouse conditions. After soil amendment, agronomic growth parameters and soil parameters were analyzed. The degree of expression of phytoalexins and defense genes was carried out by UPLC-DAD- HRESI–MS (+) and qRT-PCR analyses, respectively. The results obtained show that soil treatment with these composites improves the sanitary quality of cocoa seedlings in controlled conditions through the stimulation of agronomic growth parameters such as plant height, number of leaves, leaf surface area, and fresh weight of shoot and root. The latter leads to an increase in soil pH by about 32 % as well as the improvement of the nutritional status of the soil by 90%. Moreover, bio-oyster shell soil amendment induces up-regulation of TcPer-1, TcGlu1, TcChiB, and TcMYBPA genes and accumulation of primed metabolites such as flavonols, brevifolin, and isoflavone compounds before and after infection. This stimulation based on biological substances make it possible to pre-immunize cocoa plants against pathogen attacks and would be a good candidate to improve the quality of cocoa seeds in Cameroon