Details

Autor(en) / Beteiligte

• Cauz‐Santos, Luiz A.
• Dodsworth, Steven
• Samuel, Rosabelle
• Christenhusz, Maarten J. M.
• Patel, Denise
• Shittu, Taiwo
• Jakob, Aljaž
• Paun, Ovidiu
• Chase, Mark W.

Titel

Genomic insights into recent species divergence in Nicotiana benthamiana and natural variation in Rdr1 gene controlling viral susceptibility

Ist Teil von

• The Plant journal : for cell and molecular biology, 2022-07, Vol.111 (1), p.7-18

Ort / Verlag

England: Blackwell Publishing Ltd

Erscheinungsjahr

2022

Quelle

Wiley-Blackwell Journals

Beschreibungen/Notizen

• SUMMARY One of the most commonly encountered and frequently cited laboratory organisms worldwide is classified taxonomically as Nicotiana benthamiana (Solanaceae), an accession of which, typically referred to as LAB, is renowned for its unique susceptibility to a wide range of plant viruses and hence capacity to be transformed using a variety of methods. This susceptibility is the result of an insertion and consequent loss of function in the RNA‐dependent RNA polymerase 1 (Rdr1) gene. However, the origin and age of LAB and the evolution of N. benthamiana across its wide distribution in Australia remain relatively underexplored. Here, we have used multispecies coalescent methods on genome‐wide single nucleotide polymorphisms (SNPs) to assess species limits, phylogenetic relationships and divergence times within N. benthamiana. Our results show that the previous taxonomic concept of this species in fact comprises five geographically, morphologically and genetically distinct species, one of which includes LAB. We provide clear evidence that LAB is closely related to accessions collected further north in the Northern Territory; this species split much earlier, c. 1.1 million years ago, from their common ancestor than the other four in this clade and is morphologically the most distinctive. We also found that the Rdr1 gene insertion is variable among accessions from the northern portions of the Northern Territory. Furthermore, this long‐isolated species typically grows in sheltered sites in subtropical/tropical monsoon areas of northern Australia, contradicting the previously advanced hypothesis that this species is an extremophile that has traded viral resistance for precocious development. Significance Statement Nicotiana benthamiana, native to Australia, is an important model organism in plant/virus research because the single genotype known (LAB) has an insertion in the Rdr1 gene inactivating virus resistance. Here, we provide clear evidence that N. benthamiana comprises five species, one of which includes LAB and accessions from the northern Northern Territory in which the Rdr1 insertion is variable, leading us to conclude that the insertion is not related to the extremophile hypothesis for this species.