The effect of tetraploidization of wild Arachis on leaf morphology and other drought-related traits

Cultivated peanut is an allotetraploid (genome type AABB) with a very narrow genetic base, therefore wild species are an attractive source of new variability and traits. Because most wild species are diploid, the first step of introgression usually involves hybridization of wild species and polyploidization to produce a synthetic allotetraploid (AABB) that is sexually compatible with peanut. This study investigates drought-related traits such as leaf morphology, transpiration profile, chlorophyll meter readings (SCMR), specific leaf area (SLA) and transpiration rate per leaf area for two wild diploids (Arachis duranensis and Arachis ipaënsis) that could be of interest for improvement of the peanut crop. Furthermore, the inheritance of the traits from the diploid to the tetraploid state was investigated. Results showed that whilst some diploid traits such as SCMR, are maintained through hybridization and polyploidization, most characters, such as the leaf area, stomata size, trichome density and transpiration profile, are substantially modified. The study concludes that direct evaluations of drought-related traits in wild diploids may be useful for evaluation of wild species to be used in introgression. However, evaluations on wild-derived synthetic tetraploids are likely to be more informative.