Jim Leebens-Mack

University of Georgia | UGA · Department of Plant Biology

Sex chromosomes have evolved hundreds of independent times across eukaryotes. As genome sequencing, assembly, and scaffolding techniques rapidly improve, it is now feasible to build fully phased sex chromosome assemblies. Despite technological advances enabling phased assembly of whole chromosomes, there are currently no standards for representing...

CAM photosynthesis has evolved repeatedly across the plant tree of life, yet our understanding of the genetic convergence across independent origins remains hampered by the lack of comparative studies. Here, we explore gene expression profiles in eight species from the Agavoideae (Asparagaceae) encompassing three independent origins of CAM. ●Using...

The 1,000 Plants (1KP) initiative was the first large-scale effort to collect next-generation sequencing (NGS) data across a phylogenetically representative sampling of species for a major clade of life, in this case the Viridiplantae, or green plants. As an international multidisciplinary consortium, we focused on plant evolution and its practical...

Background and aims: CAM photosynthesis is often considered to be a complex trait, requiring orchestration of leaf anatomy and physiology for optimal performance, but the observation of trait correlations is based largely on comparisons between C3 and strong CAM species, resulting in a lack of understanding as to how such traits evolve and the lev...

Green plants (Viridiplantae) include around 450,000–500,000 species1,2 of great diversity and have important roles in terrestrial and aquatic ecosystems. Here, as part of the One Thousand Plant Transcriptomes Initiative, we sequenced the vegetative transcriptomes of 1,124 species that span the diversity of plants in a broad sense (Archaeplastida),...

Green plants (Viridiplantae) include around 450,000–500,000 species1,2 of great diversity and have important roles in terrestrial and aquatic ecosystems. Here, as part of the One Thousand Plant Transcriptomes Initiative, we sequenced the vegetative transcriptomes of 1,124 species that span the diversity of plants in a broad sense (Archaeplastida),...

Background and Aims CAM photosynthesis is often considered to be a complex trait, requiring orchestration of leaf anatomy and physiology for optimal performance. But the observation of trait correlations is based largely on comparisons between C 3 and strong CAM species, resulting in a lack of understanding as to how such traits evolve and the leve...

Determining how genes are associated with traits in plants and other organisms is a major challenge in modern biology. The unPAK project — undergraduates Phenotyping Arabidopsis Knockouts — has generated phenotype data for thousands of non‐lethal insertion mutation lines within a single Arabidopsis thaliana genomic background. The focal phenotypes...

Crassulacean acid metabolism (CAM) is a carbon-concentrating mechanism that has evolved numerous times across flowering plants and is thought to be an adaptation to water limited environments. CAM has been investigated from physiological and biochemical perspectives, but little is known about how plants evolve from C3 to CAM at the genetic or metab...

Crassulacean acid metabolism (CAM) photosynthesis is a modification of the core C3 photosynthetic pathway that improves the ability of plants to assimilate carbon in water-limited environments. CAM plants fix CO2 mostly at night, when transpiration rates are low. All of the CAM pathway genes exist in ancestral C3 species, but the timing and magnitu...

The origin of sex chromosomes has been hypothesized to involve the linkage of factors with antagonistic effects on male and female function. Garden asparagus (Asparagus officinalis L.) is an ideal species to test this hypothesis, as the X and Y chromosomes are cytologically homomorphic and recently evolved from an ancestral autosome pair in associa...

Sweetpotato [Ipomoea batatas (L.) Lam.] is a globally important staple food crop, especially for sub-Saharan Africa. Agronomic improvement of sweetpotato has lagged behind other major food crops due to a lack of genomic and genetic resources and inherent challenges in breeding a heterozygous, clonally propagated polyploid. Here, we report the genom...

Crassulacean acid metabolism (CAM) photosynthesis is a modification of the core C3 photosynthetic pathway that improves the ability of plants to assimilate carbon in water-limited environments. CAM plants fix CO2 mostly at night, when transpiration rates are low. All of the CAM pathway genes exist in ancestral C3 species, but the timing and magnitu...

Premise of the Study We present the first plastome phylogeny encompassing all 77 monocot families, estimate branch support, and infer monocot‐wide divergence times and rates of species diversification. Methods We conducted maximum likelihood analyses of phylogeny and BAMM studies of diversification rates based on 77 plastid genes across 545 monoco...

We present reference-quality genome assembly and annotation for the stout camphor tree (SCT; Cinnamomum kanehirae [Laurales, Lauraceae]), the first sequenced member of the Magnoliidae comprising four orders (Laurales, Magnoliales, Canellales, and Piperales) and over 9,000 species. Phylogenomic analysis of 13 representative seed plant genomes indica...

Highlight Although large differences in metabolism exist between C 3 and CAM species, we find that many CAM genes have shared expression patterns regardless of photosynthetic pathway, suggesting ancestral propensity for CAM. Abstract Crassulacean acid metabolism (CAM) is a carbon-concentrating mechanism that has evolved numerous times across flowe...

Poppies (Papaver), columbines (Aquilegia), buttercups (Ranunculus) and related species, are members of the order Ranunculales, the sister lineage to all other eudicots. Using coalescent and concatenated methods to analyse alignments of 882 putatively single copy genes, we have developed a robust phylogenetic tree including 27 species representing a...

Background: Storage roots are an ecologically and agriculturally important plant trait that have evolved numerous times in angiosperms. Storage roots primarily function to store carbohydrates underground as reserves for perennial species. In morning glories, storage roots are well characterized in the crop species sweetpotato, where starch accumul...

Premise of the study: The slipper orchids (Cypripedioideae) are a morphologically distinct subfamily of Orchidaceae. They also have some of the largest genomes in the orchids, which may be due to polyploidy or some other mechanism of genome evolution. We generated 10 transcriptomes and incorporated existing RNA-seq data to infer a multilocus nucle...

PREMISE OF THE STUDY Previous phylogenetic studies employing molecular markers have yielded various insights into the evolutionary history across Brassicales, but many relationships between families remain poorly supported or unresolved. A recent phylotranscriptomic approach utilizing 1155 nuclear markers obtained robust estimates for relationships...

Premise of the study: The relative ease of high throughput sequencing is facilitating comprehensive phylogenomic and gene expression studies, even for nonmodel groups. To date, however, these two approaches have not been merged; while phylogenomic methods might use transcriptome sequences to resolve relationships, assessment of gene expression pat...

Yucca moths (Prodoxidae) have long been considered by taxonomists to be basally positioned within the Lepidoptera in the superfamily Adeloidea. Recently, phylogenomic reconstructions of ordinal lepidopteran relationships using transcriptome data confirmed the basal position of the Adeloidea and the positioning of the Tegeticula pollinating yucca mo...

Crassulacean acid metabolism (CAM) is a water-use efficient adaptation of photosynthesis that has evolved independently many times in diverse lineages of flowering plants. We hypothesize that convergent evolution of protein sequence and temporal gene expression underpins the independent emergences of CAM from C 3 photosynthesis. To test this hypoth...

Sex chromosomes evolved from autosomes many times across the eukaryote phylogeny. Several models have been proposed to explain this transition, some involving male and female sterility mutations linked in a region of suppressed recombination between X and Y (or Z/W, U/V) chromosomes. Comparative and experimental analysis of a reference genome assem...

Even though lateral movements of transposons across families and even phyla within multicellular eukaryotic kingdoms have been found, little is known about transposon transfer between the kingdoms Animalia and Plantae. We discovered a novel non-LTR retrotransposon, AdLINE3, in a wild peanut species. Sequence comparisons and phylogenetic analyses in...

Background The evolution of gene body methylation (gbM), its origins, and its functional consequences are poorly understood. By pairing the largest collection of transcriptomes (>1000) and methylomes (77) across Viridiplantae, we provide novel insights into the evolution of gbM and its relationship to CHROMOMETHYLASE (CMT) proteins. Results CMTs a...