Involvement of Abscisic Acid and Jasmonic Acid Biosynthesis-related Genes in Cucurbita pepo L. Tolerance to Trace Metal Stress

Abstract

Trace metal induced stress is an abiotic factor that limits crop yield, having the additional hazard of their accumulation along trophic chain. This fact supposes an emerging problem concerning the health of the population in the case of edible plants such as Cucurbita pepo (zucchini). Most of the plant physiological responses to this adverse situation are regulated by phytohormones, being abscisic acid (ABA) and jasmonic acid (JA) the most important ones, which biosynthesis comprises a key step in this hormone-mediated signaling. In this work, genes involved in ABA and JA biosynthesis have been searched in the zucchini genome, and their expression has been analyzed in leaves of adult plants subjected to Cd- or Ni-induced stress. The results showed the higher sensitivity of zucchini plants to Ni in comparison to Cd, with a higher phenotypic affection and a major decrease of total dry weight. The study of the expression of 12 target genes (5 related to JA biosynthesis and 7 related to ABA biosynthesis), allowed determining a similar genetic response in C. pepo to these metals. The results extend our knowledge of the role of phytohormones on trace metal stress tolerance. Among all the studied genes, the main ones involved in plant responses to trace metal stress were the ABA-related CpAAO3, CpZEP, and CpNCED4, as well as the JA-related CpLOX2, CpOPR3, CpAOS2, and CpJAR1. These results provide relevant information to be used in future breeding programs.