Björn Usadel and colleagues report the genome sequence of the wild tomato species Solanum pennellii. The authors identify genes important for stress tolerance, metabolism and fruit maturation and suggest that transposable elements have had an important role in the evolution of the S. penellii stress response. Solanum pennellii is a wild tomato species endemic to Andean regions in South America, where it has evolved to thrive in arid habitats. Because of its extreme stress tolerance and unusual morphology, it is an important donor of germplasm for the cultivated tomato Solanum lycopersicum1. Introgression lines (ILs) in which large genomic regions of S. lycopersicum are replaced with the corresponding segments from S. pennellii can show remarkably superior agronomic performance2. Here we describe a high-quality genome assembly of the parents of the IL population. By anchoring the S. pennellii genome to the genetic map, we define candidate genes for stress tolerance and provide evidence that transposable elements had a role in the evolution of these traits. Our work paves a path toward further tomato improvement and for deciphering the mechanisms underlying the myriad other agronomic traits that can be improved with S. pennellii germplasm.

Significance: One of the most important technological advances by humans is the domestication of plant species for the production of food. We have used high-throughput sequencing to identify changes in DNA sequence and gene expression that differentiate cultivated tomato and its wild relatives. We also identify hundreds of candidate genes that have evolved new protein sequences or have changed expression levels in response to natural selection in wild tomato relatives. Taken together, our analyses provide a snapshot of genome evolution under artificial and natural conditions.

INTRODUCTION: Tomato (Solanum lycopersicum) is one of the most important vegetable plants in the world. It originated in western South America, and domestication is thought to have occurred in Central America. Because of its importance as food, tomato has been bred to improve productivity, fruit quality, and resistance to biotic and abiotic stresses. Tomato has been widely used not only as food, but also as research material. The tomato plant has many interesting features such as fleshy fruit, a sympodial shoot, and compound leaves, which other model plants (e.g., rice and Arabidopsis) do not have. Most of these traits are agronomically important and cannot be studied using other model plant systems. There are 13 recognized wild tomato species that display a great variety of phenotypes and can be crossed with the cultivated tomato. These wild tomatoes are important for breeding, as sources of desirable traits, and for evolutionary studies. Current progress on the tomato genome sequencing project has generated useful information to help in the study of tomato. In addition, the tomato belongs to the extremely large family Solanaceae and is closely related to many commercially important plants such as potato, eggplant, peppers, tobacco, and petunias. Knowledge obtained from studies conducted on tomato can be easily applied to these plants, which makes tomato important research material. Because of these facts, tomato serves as a model organism for the family Solanaceae and, specifically, for fleshy-fruited plants.

Arabidopsis SOG1 (suppressor of gamma response 1) is a plant‐specific transcription factor that governs the DNA damage response. Here we report that SOG1 is phosphorylated in response to DNA damage, and that this phosphorylation is mediated by the sensor kinase ataxia telangiectasia mutated (ATM). We show that SOG1 phosphorylation is crucial for the response to DNA damage, including transcriptional induction of downstream genes, transient arrest of cell division and programmed cell death. Although the amino‐acid sequences of SOG1 and the mammalian tumour suppressor p53 show no similarity, this study demonstrates that ATM‐mediated phosphorylation of a transcription factor has a pivotal role in the DNA damage response in both plants and mammals.