MCA-PGR: A Phylogenetically Informed Investigation of Transcriptome Evolution and Transcriptome Response of the Tropical Crop Genus Leucaena (Leguminosae) to Psyllid Herbivores

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PI: C. Donovan Bailey (New Mexico State University - Las Cruces)Senior Collaborator - Colin Hughes (Zurich Botanical Garden)The extensive application of next generation sequencing in agricultural research has focused on yield improvements in the most important global food crops (e.g., corn, wheat, rice, and soybean). However, lesser-known crops in tropical systems are also of tremendous significance; yet these receive comparatively little research attention. Several such plant groups are broadly known as "multipurpose crops", often representing key elements in sustainable agriculture that are fundamental to production gains in mainstream crops grown in impoverished regions. One such lesser-known system includes members of the genus Leucaena, which comprises 24 nitrogen-fixing species of small trees and shrubs. The unusually high leaf protein content of Leucaena (particularly L. leucocephala) helped to garner the titles "miracle tree" and "alfalfa of the tropics" and resulted in small- and large-scale plantings reaching 5 million lowland tropical hectares by the late 1980s. These introduced plantations provide: 1) unique protein-rich leaves for animal feed in livestock production systems, 2) green manure used as nitrogen-rich fertilizer for crops and for soil stabilization in alley-cropping systems, and 3) rapidly renewable woody biomass for construction, fuelwood, and even biofuels through lignocellulosic precursors. The goal of this project is to investigate how plant transcriptomes change through time and in association with diversification of species. Specifically, a cost- effective and phylogenetically informed approach will be used to sequence, assemble, and compare sets of expressed genes (transcriptomes) from all species of Leucaena. Insect feeding trials will be used to identify genes and broad metabolic pathways associated with psyllid insect resistance and susceptibility among different species of Leucaena. In addition, the project will use the data generated to investigate broad patterns of transcriptome size variation and identify some of the specific changes that have been associated with speciation through geographic isolation in comparison to hybrid speciation associated with genome duplication (allopolyploidy). Finally the data generated will be used to develop molecular markers for plant breeding and other studies.Newly developed breeding tools for tropical woody species are critical for future widespread use as contributors to sustainable agriculture in poor tropical regions of the world. NMSU is a minority serving university with existing programs successfully attracting underrepresented individuals to careers in scientific research. Furthermore, this project includes the implementation of a new course and undergraduate laboratories developed to advance interest and the understanding of plant genome research among students at a Hispanic Serving Institution using a plant system of interest to Mesoamerican culture and heritage. Support of this MCA-PGR project will provide extensive training and mentoring for the PI, associated postdoctoral fellow and graduate student who will work closely with a primary investigator applying new genomics technologies to address these research questions. Sequence data derived from this project will be made available through a project website and long-term through the NCBI's Short Read Archive. Links to specific data sources will be provided as they are developed and released at http://biology-web.nmsu.edu/bailey/.