[YLS 'yellow leaf syndrome: phytosanitary status of saccharum sp. In Morocco and elimination of 'ScYLV' virus by in vitro culture]

ABSTRACT

The phytosanitary status of sugarcane infection by Sugarcane Yellow Leaf Virus [ScYLV] in Morocco was studied using virus detection by tissue blot immunoassay [TBIA]. Test results revealed that the wild cane as well as 5/6 variety of the industrial culture of Gharb and Loukkos perimeters and 6/7 variety of Moroccan sugarcane collection are infected by ScYLV, sometimes even in the absence of visual symptoms of disease YLS. Regeneration by shoot-tip culture showed that the micro-cutting is improved by using the antioxidants DIECA and the adsorbent of phenolic substances PVP combined with [i] pre-culture in darkness and [ii] frequent transplanting on fresh medium. These treatments reduced browning induced by phenols excreted by explants. The growth of micro-cutting was stimulated by the use of GA3 combined with AIB. The vitro-shoots multiplication was best carried out in the presence of cytokinins [Kin + BAP]. Rooting was favoured by a high concentration of AIB in the culture medium. On the other hand, regeneration by novo-formation on callus derived from sheath of young leaves showed the necessity of the 2,4-D to induce callus embryogenesis and the use of the basic medium without auxin to develop the complete vitro-plantlets. Moreover, tissue-blot immunoassay [ELISA] showed that 20 and 100% of vitroplantlets were free from ScYLV respectively, by shoot-tip culture and callus embryogenesis