Molecular detection of sugarcane striate virus and sugarcane white streak virus and their prevalence in the Miami World Collection of sugarcane and related grasses

Viruses in the genus Mastrevirus (family Geminiviridae), including those infecting sugarcane, have natural geographical ranges almost exclusively restricted to Africa and the Indian Ocean islands off the African coast. Only sugarcane white streak virus (SWSV) in Barbados and sugarcane striate virus (SStrV) in Florida and Guadeloupe are known to infect a few sugarcane varieties in the Western Hemisphere. In this study, PCR assays were developed to detect these two viruses in sugarcane. Five hundred and seventy-one DNA samples from Saccharum species and interspecific hybrids from the Miami World Collection of sugarcane and related grasses were tested for the presence of SStrV and SWSV by PCR. No variety was found infected by SWSV but SStrV was detected in 19 varieties. PCR data were confirmed by sequencing amplified fragments (248 bp). These fragments shared 93%–100% nucleotide identity with SStrV sequences from the GenBank database. SStrV isolates were distributed in six phylogenetic groups, including the four strains of the virus. Most varieties infected by SStrV originated from Asia, thus confirming a previous hypothesis stating that this virus originated from this continent. Absence of SStrV in commercial sugarcane in Florida also suggested that this virus has not been spread in this location, while infected plants have been present for several decades.     

Reducing urban sprawl by optimizing housing production

Scholars demonstrated the importance of house planners in the creation of environmentally friendly homes. Despite the lack of broad agreement on the type of freehold estate that could reduce urban sprawl, the authors agree on the role of government and developers in housing planning and construction. According to a recent study, the government and developers are investing in freehold estates to promote sustainable urban growth. However, this study employs urban growth theories to explain the policy's success. First, we examine the rate of urban growth and the trends in urban sprawl. The affordability of ground-floor and three-story buildings is then assessed. The findings show that 19.36 square kilometers of built-up area contributed to land use expansion in Abomey-Calavi, Benin Republic, between 1974 and 2015, and four districts are at higher risk of environmental degradation. To mitigate this, three-story buildings could be inclusive and improve efficient land use, thereby limiting urban sprawl.