SRA

This project involves preliminary research for the introduction of increased drought tolerance into the cultivated peanut. We propose to conduct a transcriptional analysis of Arachis ipaensis Krapov. and W.C. Gregory (B genome donor) and Arachis dardani for presence of candidate genes for drought tolerance. A. ipaensis is one of the recognized progenitor species for cultivated peanut and currently has a published genome sequence available to serve as a reference genome. A. dardani is a species with putative drought tolerance that is native to the Caatinga shrublands of Northeastern Brazil. This area is considered a dry forest region and receives less the 250 mm of annual precipitation (McGinley, 2014). The two species will be subjected to simulated imposed drought . A trial of completely random design consisting of 3 replications, with control, will be grown in greenhouses at the Texas A&M Research and Extension Center at Stephenville. Seed will be pre-germinated in a Stultz germinator for four days. Plants will be planted in an IBG greenhouse operating on a Wadsworth temperature control system with a day time temperature of 27oC and a night time temperature of 21oC. In order to simulate tropical conditions, ambient humidity in the greenhouse will be increased with evaporative coolers. In addition, day length will be extended through the use of supplemental lighting. Daytime temperature is further controlled with the use on 63% shade cloths during peak summer temperatures. Plants will be grown in half bushel baskets with a top soil mixture of Winthorst fine sandy loam. Irrigation will be applied by Rainbird 2 gph trickle irrigation emitters. Drought will be simulated by removal of irrigation. Drought will be imposed during the late pod set period of development. Tissue samples will be collected in three distinct physiological states. These will be (1) a pre-stress period immediately prior to simulated drought, (2) a stress period during the simulated drought conditions, (3) a post-stress period immediately following the restoration of irrigation. Root, leaf, and apical meristem tissue will be collected and RNA will be separately extracted from the two peanut lines at the Texas A&M Research and Extension Center at Stephenville and we request the AgriLife Genomics and Bioinformatics Service sequence and analyze 32 samples for differences in RNA expression. This will serve as preliminary data that can be used in ongoing gene introgression programs and will complement an internally funded project with the AgriLife Genomics and Bioinformatics Service to conduct RADSeq for marker development for the peanut germplasm collection in Stephenville, including both lines used in this transcriptional study.