Increased oxidative stress, lipid peroxidation and protein degradation trigger senescence in Iris versicolor L. flowers

Abstract

Dynamics in various physiological and biochemical aspects were studied during various stages (Itight bud stage to VI-senescent stage) of flower development in Iris versicolor. Floral diameter, fresh & dry mass and water content increased during flower opening and decreased towards senescence. Senescence was found to be related to the increased lipid peroxidation which was reflected in the decreased membrane stability index towards senescence. This increase in the lipid peroxidation was probably initiated by increased lipoxygenase activity which shot up just prior to the increase in lipid peroxidation. Soluble protein content showed a marginal decrease towards senescence with a corresponding increase in specific protease activity. Sugar fractions and a-amino acids showed a significant decrease towards senescence. Superoxide dismutase and ascorbate peroxidase activity increased as the flowers opened and thereafter a significant decrease was registered towards senescence. Catalase activity improved as the flower matures, but decreased prior to flower opening through senescence. The protein patterns from the tepal tissues resolved through electrophoresis showed a consistency in proteins upto the flower opening but a marginal decrease was registered in both high and low molecular weight proteins towards senescence. However, a protein of molecular weight 76.5 kDa showed up during senescent stages which may have a role in flower senescence.

Physicochemical quality, antioxidant capacity and nutritional value of edible flowers of some wild dahlia species

“…On day 3, the cherry and white ligules stood out the most, with a tendency to increase the weight values, while on the fifth day this behaviour was reversed and those with greater weights were the cherry, yellow, and white ligules. Similar results have been reported in several other species such as Iris versicolor (Ahmad and Tahir, 2016), Gerbera jamesonii (Babarabie et al, 2016), Lilium spp., and Rosa hybrid (Ren et al, 2017). The accumulation of citric acid on day 1 was higher for D. brevis, D. merckii and D. coccinea (1.4, 1.2 and 1.3 %, respectively), however, on day 3, it decreased to 0.7 and 0.9% (D. merckii and D. coccinea), increasing again on day 5 to 2.7 and 3.1%, while the lowest values were present in D. × hortorum in the yellow, white and cherry ligules.…”

“…The accumulation of citric acid on day 1 was higher for D. brevis, D. merckii and D. coccinea (1.4, 1.2 and 1.3 %, respectively), however, on day 3, it decreased to 0.7 and 0.9% (D. merckii and D. coccinea), increasing again on day 5 to 2.7 and 3.1%, while the lowest values were present in D. × hortorum in the yellow, white and cherry ligules. In this regard, Ahmad and Tahir (2016) indicate that cut flowers have a temporary variation in their fresh weight due to the opening of the floral bud; however, this fresh weight decreases as translocation of nutrients from other organs occurs (leaves and stems), which concludes with senescence (Ren et al, 2017), since, according to Lara-Cortés et al (2016) and Azuma et al (2019), dahlia inflorescences do not show sensitivity to the presence of external ethylene.…”

“…On the other hand, the most visible problems of post-harvest handling of edible flowers and inflorescences are related to their high perishability due to their lack of photoassimilate accumulation organs, high sensitivity to ambient temperature and mechanical damage (Zeng et al, 2014;Ahmad and Tahir, 2016), as a result of which floral structures tend to undergo changes not only in their external appearance (colour and turgor), but also in their nutritional composition (phenolic compounds, flavonoids, vitamins) and their antioxidant capacity (Kaisoon et al, 2011;Gebremedhin et al, 2013;Liu et al, 2016) Therefore, studies of the variation in these compounds are of paramount importance for determining its magnitude and the possibility of implementing post-harvest conservation methods that allow maintaining and preserving the quality of flowers and inflorescences for use as food (Mlcek and Rop, 2011;Rachkeeree et al, 2018).…”

“…It is represented by 37 species in the genus Dhalia that belongs to the Asteraceae family. They produce flowers with a great diversity of colours (red, purple, pink, white and variegated) (Ohno et al, 2013;Ahmad and Tahir, 2016), and that is why they are cultivated mainly for the production of cut flowers, potted plants and elements for the design and construction of gardens (Younis et al, 2014). The flowers of dahlias also have nutritional and functional properties that make them suitable for consumption as food (Lara-Cortés et al, 2013;Lara-Cortés et al, 2016).…”

Physiological and biochemical aspects of flower development and senescence in Nicotiana plumbaginifolia Viv.

“…Flower petals are considered ideal tissues for senescence studies as they are short-lived, the tissue is relatively homogenous and chemical manipulation can be applied without substantial wounding (van Doorn and Woltering 2008, Reid and Jiang 2012, Ahmad and Tahir 2016b. Flower senescence is initiated by an array of external and internal factors which initiate a series of physiological and biochemical events orchestrated by plant hormones.…”