Transposable elements and the plant pan-genomes.

The comparative sequencing of several grass genomes has revealed that transposable elements are largely responsible for extensive variation in both intergenic and local genic content, not only between closely related species but also among individuals within a species. These observations indicate that a single genome sequence might not reflect the entire genomic complement of a species, and prompted us to introduce the concept of the plant pan-genome, which includes core genomic features that are common to all individuals and a dispensable genome composed of partially shared and/or non-shared DNA sequence elements. Uncovering the intriguing nature of the dispensable genome, namely its composition, origin and function, represents a step forward towards an understanding of the processes that generate genetic diversity and phenotypic variation. The developing view of transcriptional regulation as a complex and modular system, in which long-range interactions and the involvement of transposable elements are frequently observed, lends support to the possibility of an important functional role for the dispensable genome and could make it less dispensable than previously thought.

Morgante M ，De Paoli E ，Radovic S 《CURRENT OPINION IN PLANT BIOLOGY》

The evolution of plant genomes: scaling up from a population perspective.

Plant genomes exhibit tremendous diversity in both their size and structure, with genome sizes across land plants ranging over two to three orders of magnitude and significant variation in structural organization was observed across species (EA Kellogg, JL Bennetzen, The evolution of nuclear genome structure in seed plants, Am J Bot 2004, 91:1709-1725). Five plant genomes are now either completely sequenced or in the draft stage; the grape (O Jaillon et al., The grapevine genome sequence suggests ancestral hexaploidization in major angiosperm phyla, Nature 2007, 449:463-467) and papaya (R Ming et al., The draft genome of the transgenic tropical fruit tree papaya (Carica papaya Linnaeus), Nature 2008, 452:991-997) whole genome sequences were reported most recently. Moreover, sequencing of 41 additional genomes is in progress. There is now an emerging consensus that understanding genome evolution requires consideration of the population genetics of genome diversification, and that description of evolutionary forces at the level of populations and within species can help identify the features that led to plant genome diversity (M Lynch, JS Conery, The origins of genome complexity, Science 2003, 302:1401-1404). In this review we focus on advances in our understanding of the mechanisms that drive the diversification of genomes. In particular, we look at the extent to which demographic features such as effective population size changes within species can drive genome evolution, discuss population genetic models of genome diversification associated with transposable element (TE) mobilization, and describe recent studies on the evolution of gene families.

Flowers JM ，Purugganan MD 《-》

Plant genome organisation and diversity: the year of the junk!

Morgante M 《CURRENT OPINION IN BIOTECHNOLOGY》

Transposable elements, gene creation and genome rearrangement in flowering plants.

Bennetzen JL 《CURRENT OPINION IN GENETICS & DEVELOPMENT》

Give-and-take: interactions between DNA transposons and their host plant genomes.

Dooner HK ，Weil CF 《CURRENT OPINION IN GENETICS & DEVELOPMENT》