Evolutionary history of the Asr gene family

NICOLÁS FRANKEL; FERNANDO CARRARI; ESTEBAN HASSON; NORBERTO D. IUSEM

GENE

ELSEVIER SCIENCE BV

Año: 2006 vol. 378 p. 74 - 83

0378-1119

The Asr gene family is widespread in higher plants. Most Asr genes are up-regulated under different environmental stress conditions and during fruitripening. ASR proteins are localized in the nucleus and their likely function is transcriptional regulation. In cultivated tomato, we identified a novel fourthfamily member, named Asr4, which maps close to its sibling genes Asr1–Asr2–Asr3 and displays an unshared region coding for a domain containing a 13-amino acid repeat. In this work we were able to expand our previous analysis for Asr2 and investigated the coding regions of the four known Asr paralogousgenes in seven tomato species fromdifferent geographic locations. In addition, we performed a phylogenetic analysis on ASR proteins. The first conclusiondrawn from thiswork is that tomatoASR proteins cluster together in the tree. This observation can be explained by a scenario of concerted evolution or birthand death of genes. Secondly, our study showed that Asr1 is highly conserved at both replacement and synonymous sites within the genus Lycopersicon.ASR1 protein sequence conservation might be associated with its multiple functions in different tissues while the low rate of synonymous substitutionssuggests that silent variation in Asr1 is selectively constrained, which is probably related to its high expression levels. Finally, we found that Asr1 activationunder water stress is not conserved between Lycopersicon species.