Abstract Detail

Comparative Genomics/Transcriptomics

Scott, Alison [1], Maher, Olivia [2], Ferreira, Alyssa [2], Trouern-Trend, Alexander [3], Figueroa-Corona, Laura [4], Matallana, Lilian [5], Whetten, Ross [5], Wegrzyn, Jill [3].

Less than evergreen: Leaf senescence transcriptomics in Larix laricina.

The visually stunning process of leaf senescence is a well coordinated breakdown process, liberating nutrients from foliage before abscission completes. The suite of biochemical and metabolic changes associated with leaf senescence have been well-characterized in angiosperms. Whereas the majority of conifers are evergreen, retaining their needles through winter and typically over multiple years, a handful of conifer species are deciduous. The Larch genus (Larix) is one of the rare lineages that undergoes seasonal leaf senesence. To study the genes involved, we collected abscission zone tissue from six individuals of tamarack, or Eastern larch (Larix laricina, Pinaceae) across Connecticut and generated transcriptome profiles for three phenotypic time points (green needles, yellow needles, and no needles). After identifying differentially expressed genes across timepoints, we assigned functional annotations and used the resulting Gene Ontology (GO) terms for enrichment analysis.  Comparing gene expression in abscission zones associated with green needles to those associated with yellow needles, upregulated gene families include ethylene-response genes, relevant as ethylene is a known mediator of leaf senescence. These gene families are also involved in leaf senescence in angiosperms, suggesting conservation of senescence pathways. Comparing differentially expressed genes in L. laricina to genes associated with foliar senesence in angiosperms, we saw further overlap in pathogenesis related genes (e.g. chitinase and thaumatin-like protein) and genes involved in chloroplast breakdown (e.g chlorophyll A/B binding protein and glucosidase), as both groups of genes are upregulated during autumnal leaf senesence in angiosperms and Larix alike. Studying these upregulated gene families in a phylogenetic context may reveal to what extent seasonal senescence in the few deciduous conifer lineages is reliant on the same gene families.

1 - University of California, Davis, Plant Sciences, One Shields Ave, Davis, California, 95616, United States
2 - University of Connecticut, EEB
3 - University of Connecticut, Ecology & Evolutionary Biology, 75 N Eagleville Road, Unit 3043, Storrs, CT, 06269, United States
4 - Universidad Nacional Autónoma de México
5 - NC State, Department of Forestry and Environmental Resources

Gene expression

Presentation Type: Oral Paper
Session: CG1, Functional & Comparative Genetics/Genomics I
Location: Virtual/Virtual
Date: Tuesday, July 28th, 2020
Time: 2:15 PM
Number: CG1008
Abstract ID:677
Candidate for Awards:None

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