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

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.Funding for open access charge: CRUE-Universitat Jaume

Impact of nickel toxicity on growth, fruit quality and antioxidant response in Zucchini squash (Cucurbita pepo L.)

The impact of trace metal elements (TMEs) on plants is one current pollution problem, the severity of which is increasing with industrial development, population growth and inappropriate agricultural practices. The latter can have irreversible effects on ecosystems, including species extinction, trophic chain contamination and altered human health, particularly in the case of consumed plants such as zucchini squash (Cucurbita pepo L.). This study aims to investigate the effects of nickel on various physiological and biochemical parameters of zucchini growth, with a particular focus on how this toxic metal impacts the quality of fruit that is consumed by humans. To achieve this, plants aged 45 days were grown for one month on solid media loaded with different concentrations of Ni (0, 100, 300 and 500 µM). The results showed that exposure of plants to Ni resulted in significantly altered growth and higher accumulation of Ni in the shoots (1314 µg·g−1 DW) than in roots and fruits. Concerning non-enzymatic antioxidants, the results showed that Ni toxicity significantly increased total polyphenols, especially in shoots at 300 µM Ni, while flavonoid content decreased in the roots and shoots in response to Ni treatment. Our results also show that nickel tolerance in C. pepo is ensured by a combination of several mechanisms such as an increase in the content of proline. This species can survive and tolerate, to different degrees, toxic cations at concentrations up to 500 µM but with visible symptoms of toxicity such as chlorosis of the leaves. Indeed, based on thresholds of hyperaccumulation, we can qualify Cucurbita pepo as a hyperaccumulator species of nickel

Impact of Nickel Toxicity on Growth, Fruit Quality and Antioxidant Response in Zucchini Squash (Cucurbita pepo L.)

The impact of trace metal elements (TMEs) on plants is one current pollution problem, the severity of which is increasing with industrial development, population growth and inappropriate agricultural practices. The latter can have irreversible effects on ecosystems, including species extinction, trophic chain contamination and altered human health, particularly in the case of consumed plants such as zucchini squash (Cucurbita pepo L.). This study aims to investigate the effects of nickel on various physiological and biochemical parameters of zucchini growth, with a particular focus on how this toxic metal impacts the quality of fruit that is consumed by humans. To achieve this, plants aged 45 days were grown for one month on solid media loaded with different concentrations of Ni (0, 100, 300 and 500 µM). The results showed that exposure of plants to Ni resulted in significantly altered growth and higher accumulation of Ni in the shoots (1314 µg·g−1 DW) than in roots and fruits. Concerning non-enzymatic antioxidants, the results showed that Ni toxicity significantly increased total polyphenols, especially in shoots at 300 µM Ni, while flavonoid content decreased in the roots and shoots in response to Ni treatment. Our results also show that nickel tolerance in C. pepo is ensured by a combination of several mechanisms such as an increase in the content of proline. This species can survive and tolerate, to different degrees, toxic cations at concentrations up to 500 µM but with visible symptoms of toxicity such as chlorosis of the leaves. Indeed, based on thresholds of hyperaccumulation, we can qualify Cucurbita pepo as a hyperaccumulator species of nickel