Cassava (Manihot esculenta Crantz) is an important crop that constitutes staple food and income for 800 million people worldwide. Cassava yield in Côte d'Ivoire is reduced due to a variety of factors, including cassava mosaic disease. Despite the impact of the pathogen Cassava Mosaic Virus (CMV) on production, genetic diversity of this virus is rarely studied in Côte d'Ivoire. This study aims to assess the molecular variability of CMV occurring in three of large cassava production area of Côte d’Ivoire. Symptomatic and asymptomatic cassava leaves were collected for genomic DNA extraction and molecular identification was performed by polymerase chain reaction (PCR). Amplified DNA was sequenced and analyzed in silico. 68% of infections were identified as African Cassava Mosaic Virus strains. Sequences alignment to Genbank sequences showed high similarity with sequences of virus from Côte d’Ivoire, Ghana, Kenya, Cameroun, Madagascar, and Nigeria. The virus's rapid evolution was demonstrated by a high mutation rate at the protein level. A phylogenetic analysis also revealed seven new genotypes of ACMV strain. This result reflects a progressive genetic evolution of the virus strains, which could impact negatively on cassava crop in Côte d'Ivoire. This study proposed selecting resistant traditional cassava genotypes to control virus spread. Key words: Cassava mosaic disease, ACMV, in silico analysis, mutation, resistant genotype, Côte d’Ivoire.
Autotetraploid rice is a new germplasm developed through diploid chromosome doubling. Hybrids developed by indica autotetraploid rice crossed by japonica autotetraploid rice has clear biological advantage on F1, causing widespread concerns for special research evolution to evaluate and utilize F1 hybrid vigor. However, the widespread fertility of F1 indica and japonica autotetraploid rice is low, which makes it difficult to direct utilization of F1 vigor. In diploid indica and japonica rice, the fertility of F1 hybrids is also proved to be low. Embryo sac infertility is known to be one of the most important reasons for hybrid sterility and many studies has indicated that the primary cause of F1 sterility was abortion of the embryo sac, which was identified by the genotype of the S5 gene on the chromosome. Previous studies have cloned S5 based on common wild rice and cultivated rice and S5 sequence was obtained and studied. In this paper, typical sequence of different materials of S5 japonica and indica rice group of autotetraploid hybrids observed with whole-mount eosin B-staining confocal laser scanning microscopy WE-CLSM was utilized, to overcome F1 hybrids embryo sac sterility. Key words: rice (Oryza sativa L.); autotetraploid; hybrid sterility; S5 gene; embryo sac fertility.
