Speaker: Claudia Martinho, senior postdoc from the Max Planck Institute for Biology in Tubingen, Germany (She will present research from her previous postdoc position with Dr. David Balcoumbe at the University of Cambridge.)

Title: "Defying Mendel’s laws: sulfurea paramutation unveils new principles of epigenetic inheritance in tomato"

Abstract: Paramutation represents a clear exception to the principles of inheritance established by Gregor Mendel in the 19th century. It involves the transfer of repressive epigenetic marks from a silent to an active allele and thereby violates Mendel’s first law of independent allele segregation. It is best known from conspicuous pigmentation phenotypes in maize but the paramutation phenomena was also reported across diverse plant and animal species. Paramutation-like events are common in tomato hybrids suggesting that paramutation may be less exceptional and rather a frequently co-occurring process during cross-hybridization. 

In this talk I will show how a classic example of paramutation sulfurea (sulf) – an understudied locus associated with a chlorosis phenotype and aberrant segregation patterns. Sulf was employed to dissect the epigenetic- and transgenerational mechanisms underlying paramutation in tomato plants. Our results show that the DNA- and histone-methyl transferases CMT3 and KYP are required for the maintenance of paramutation and that there is a change in chromatin architecture associated with the silent epiallele. We further demonstrate that in tomato the developmental and transgenerational maintenance of paramutation is independent of sRNAs, a mechanism previously suggested to explain the trans-communication between homologues across mitotic and meiotic divisions in maize. I will therefore present a revised model to explain the maintenance of paramutation in plants by integrating existing concepts into a revised framework of non-Mendelian heredity.

Host: GDCB Diversity, Equity and Inclusion Committee

Zoom link: https://iastate.zoom.us/j/96721371581?pwd=QzM3M0cycjFzYXNRdVJVYkE0MVg1QT09

Short biography: Claudia Martinho earned a Ph.D. in plant molecular biology at the Institute Gulbenkian for Science in Lisbon, Portugal, where she studied how microRNA activity is regulated in response to environmental stresses in Arabidopsis. From 2017-21, Martinho was a postdoc at the University of Cambridge (UK), studying non-Mendelian epigenetic inheritance in tomato hybrids with Dr. David Baulcombe. The seminar will be based on the research developed during this postdoc. Presently, Martinho is a senior postdoc in Germany at the Max Planck Institute for Biology in Tubingen and is studying gene-silencing in brown algae. Martinho is looking to establish her own laboratory in gene-silencing and epigenetic inheritance in crops.