ABSTRACT

The rising demand for guava fruit worldwide is due to its richness in vitamin C, high yielding and two bearing seasons. Given the salt stress threat to guavas and the necessity of protective strategies, in the present research guava seedlings were subjected to sodium chloride (0 and 50 mM) and salicylic acid (0 and 1 mM). To ascertain a logical conclusion, the activity of antioxidant enzymes, antioxidant capacity of DPPH, ferric reducing antioxidant power, total flavonoid and phenol contents were monitored in salt-exposed guava seedlings. Based on our findings, the most superoxide dismutase (87.46 µmol min⁻¹g⁻¹DW) activity, ferric reducing antioxidant power (408.82 mmol g⁻¹ DW), DPPH scavenging activity (80.65%), flavonoid (14.15 mg QE⁻¹ g DW) and phenol (34.02 mg GAE g⁻¹ DW) contents were found in 50 mM NaCl-exposed plants, which were enriched by 1 mM salicylic acid. A high correlation was observed among non-enzymatic antioxidant parameters (DPPH scavenging activity, ferric reducing antioxidant power, total flavonoid content and total phenol content). In conclusion, salicylic acid improved guavas salt tolerance by increasing both enzymatic (peroxidase and superoxide dismutase) and non-enzymatic (ferric reducing antioxidant power, DPPH scavenging activity, total phenol and flavonoid contents) pathways.

摘要

全世界对番石榴果实需求的增加是由于其富含维生素C，高产和两个生育季节。考虑到盐胁迫对番石榴的威胁以及采取保护措施的必要性，在本研究中，对番石榴幼苗进行氯化钠（0和50 mM）和水杨酸（0和1 mM）的处理。为了确定一个合理的结论，对盐浸番石榴幼苗中的抗氧化酶活性，DPPH的抗氧化能力，三价铁的抗氧化能力，总类黄酮和酚含量进行了监测。根据我们的发现，最大的超氧化物歧化酶（87.46 µmol min ^-1 g ^-1 DW）活性，三价铁的抗氧化能力（408.82 mmol g ^-1 DW），DPPH清除活性（80.65％），类黄酮（14.15 mg QE ^-1）在暴露于50 mM NaCl的植物中发现了¹ gM DW）和苯酚（34.02 mg GAE g ^-1 DW）的含量，这些植物富含1 mM水杨酸。在非酶抗氧化剂参数（DPPH清除活性，三价铁还原抗氧化剂能力，总类黄酮含量和总酚含量）之间观察到高度相关性。总之，水杨酸通过增加酶促途径（过氧化物酶和超氧化物歧化酶）和非酶促途径（铁降低抗氧化能力，DPPH清除活性，总酚和类黄酮含量）途径来改善番石榴盐耐性。