In vitro characterization of root extracellular trap and exudates of three Sahelian woody plant species.

MAIN CONCLUSION: Arabinogalactan protein content in both root extracellular trap and root exudates varies in three Sahelian woody plant species that are differentially tolerant to drought. At the root tip, mature root cap cells, mainly border cells (BCs)/border-like cells (BLCs) and their associated mucilage, form a web-like structure known as the "Root Extracellular Trap" (RET). Although the RET along with the entire suite of root exudates are known to influence rhizosphere function, their features in woody species is poorly documented. Here, RET and root exudates were analyzed from three Sahelian woody species with contrasted sensitivity to drought stress (Balanites aegyptiaca, Acacia raddiana and Tamarindus indica) and that have been selected for reforestation along the African Great Green Wall in northern Senegal. Optical and transmission electron microscopy show that Balanites aegyptiaca, the most drought-tolerant species, produces only BC, whereas Acacia raddiana and Tamarindus indica release both BCs and BLCs. Biochemical analyses reveal that RET and root exudates of Balanites aegyptiaca and Acacia raddiana contain significantly more abundant arabinogalactan proteins (AGPs) compared to Tamarindus indica, the most drought-sensitive species. Root exudates of the three woody species also differentially impact the plant soil beneficial bacteria Azospirillum brasilense growth. These results highlight the importance of root secretions for woody species survival under dry conditions.

Physical, morphological and chemical characteristics, oil recovery and fatty acid composition of Balanites aegyptiaca Del. kernels.

Balanites aegyptiaca Del. kernels were chemically, physically and morphologically characterized. Crude oil (49.0%) and crude protein (32.4%) were the two major constituents of the kernels. Phytic acid content was relatively high compared to other legumes. In contrast, antitryptic activities of the kernel flours were very low. Sapogenin contents of the full fat, defatted and testa flours were 1.5, 2.7 and 3.0%, respectively. The hardness of the kernel was found to be about 10.4 x 10(5) N/m2, which was somewhat high. The morphological structure of the kernel using a scanning electron microscope revealed that the protein matrix was embedded in a lake of oil droplets. Oil recovery, as a function of pressing time, pressure, temperature and particle size was investigated. With increasing temperature up to 70 degrees C at 400 bar, for 120 min, an oil recovery of 79.4% was obtained. Using an expeller at 115 degrees C, about 85% of the kernel oil was recovered. The reduction of particle size had a negative effect on oil recovery under the same conditions. The fatty acid composition was not affected by the pressing temperature up to 115 degrees C. The total amount of the unsaturated fatty acids was found to be up to 74.8% (50 degrees C) and 75.1% (115 degrees C) of the total fatty acids content.