Genome-wide expression dynamics of tomato (Solanum lycopersicum L.) 9- and 13-lipoxygenases identify family members with differential regulation in response to common abiotic stresses

Authors: UPADHYAY, RAKESH - Purdue University; HANDA, AVTAR - Purdue University; Mattoo, Autar

Submitted to: Genes
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 8/3/2019
Publication Date: 9/5/2019
Citation: Upadhyay, R.K., Handa, A.K., Mattoo, A.K. 2019. Genome-wide expression dynamics of tomato (Solanum lycopersicum L.) 9- and 13-lipoxygenases identify family members with differential regulation in response to common abiotic stresses. Genes. https://doi.org/10.3390/genes10090683.
DOI: https://doi.org/10.3390/genes10090683

Interpretive Summary: Tomato is an important vegetable crop and second largest horticultural crop, a worldwide industry valued at over 50 billion dollars. High tomato yields require development of tolerance to environmental extremes such as heat, cold and drought, each of these abiotic stresses impact nutrition and yield of tomatoes. Among the response pathways to these stresses is a family of oxylipins called jasmonates. The enzyme lipoxygenase (LOX) is critical to the biosynthesis of jasmonates. However, earlier research in our laboratory determined that there are 14 members in the tomato LOX gene family. It was therefore necessary to delineate which LOX isoforms/genes are crucial for the regulation of the jasmonate pathway. Here, we present responses of these 14 genes in tomato in response to common abiotic stresses, namely, heat, cold, drought and salt. This study delineates the robust and non-robust response of specific lipoxygenase gene family members in tomato. These data are necessary and important for future genetic manipulation to incorporate better traits for generation of stress tolerant tomato verities. This research is of interest to tomato breeders, scientists, plant physiologists and genetic experts.

Technical Abstract: Lipoxygenases (LOXs) (EC 1.13.11.12) catalyze the oxygenation of fatty acids to produce oxylipins including the jasmonate family of plant hormones. In tomato, among LOX genes, nine belong to the 9-LOX family and the remaining 5 to the 13-LOX family, based on the carbon oxidation position specificity of polyunsaturated fatty acids. Since jasmonates have been related to plant responses to different stresses, we determined time dependent expression dynamics of tomato LOX gene members in response to environmental stresses such as heat, cold, drought and salinity. Each stress condition led to identification of specific 9-LOX and 13-LOX gene members that were either up or down regulated. Stress-responsive cis-elements identified in other plant systems were utilized to identify tomato LOX members that harbor similar cis-elements. Clearly, there was correspondence between specific gene members harboring stress-responsive elements and their specificity in stress-mediated up and down regulation. In addition, we carried out comparative leaf transcriptome analysis between a wild relative of tomato - Solanum pimpinellifolium and the most recent cultivar - S. lycopersicum to shed light on the gain or loss of LOX genes during tomato domestication process. LOX genes in the more recent S. lycopersicum appear to have been positively multiplied during domestication process except that SlLOX13 was lost. The information generated here on the LOX gene family in tomato should help future studies to further identify their roles in-planta, and carry out their genetic manipulation for crop biotechnological intervention.