I
am a PhD student at the University of New England, Australia. I had served the
Ethiopian Institute of Agricultural Research from a Junior-to-Associate
Researcher as a breeder on cool season food legumes. Served as leader of the Ethiopian
national faba bean and field pea research program for three years and worked as
a research associate for International Livestock Research Institute, a CGIAR
centre based in Addis Ababa, Ethiopia, for four years. My PhD project is focused
on characterizing the diversity and evolution of R-gene repertoire using
long-read genomic sequences of 28 species in the broader Myrtaceae family.
Poster Number / Talk Time
Abstract: Myrtaceae tree species encodes for a potential novel class of resistance genes
T. TOLESSA 1,2 , Z. LUO 2 , P.A. TOBIAS 3 , A. JONES 2 , S. FERGUSON 2 , J. BOREVITZ 2 , S. WU 1 , R. ANDREW 1 , B. SCHWESSINGER 2
Many species of Myrtaceae, an economically and ecologically significant plant family in Australia are threatened by myrtle rust infection caused by Austropuccinia psidii. We conducted a comprehensive analysis of R-genes that encode for nucleotide-binding sites (NBS) using long-read sequences of 28 species to investigate the genetic basis of disease resistance. We predicted 1.04 million gene models encoding 47.7k NBS and leucine-rich repeat (LRR) domains. We detected 260 unique domains with diverse frequencies of integration into NBS-LRR genes. A single Jacalin domain accounted for 43.1% of the total integration frequency. Tol/interleukin-1 (TIR), which encodes for NBS but lacks LRR, was highly expanded with 1-10 copies of Jacalin (J) in its C-terminal (TNJ). TNJ formed a monophyletic clade nested within the TN that encodes for LRR (TNL) clades. Important nucleotide-binding motifs and functional amino-acid residues were conserved in the TNJ. Similar to what has been observed in LRR domains elsewhere, hyper-variable and positively selected sites were found clustered in the Jacalin region of TNJ. Thus, Jacalin may be a functional analogue of LRR in terms of pathogen molecule recognition. Our findings reveal that different tree families could evolve with different pathogen recognition specificity, and clade-specific R-gene organization might contribute to specific niche adaptation in distinct plant families. - School of Environment and Rural Science, University of New England, Armidale NSW 2351, Australia
- Australia Research School of Biology, The Australian National University, Acton, ACT 2601, Australia
- School of Life and Environmental Sciences, University of Sydney, Camperdown, NSW 2006, Australia
