Response of seed yield and biochemical traits of Eruca sativa Mill. to drought stress in a collection study.

Drought tolerance is a complex trait in plants that involves different biochemical mechanisms. During two years of study (2019-2020), the responses of 64 arugula genotypes to drought stress were evaluated in a randomized complete block design with three replications under field conditions. Several metabolic traits were evaluated, i.e. relative water content, photosynthetic pigments (chlorophyll and carotenoids), proline, malondialdehyde, enzymatic antioxidants (catalase, ascorbate peroxidase, and peroxidase), total phenolic and flavonoid contents and seed yield. On average, the drought stress significantly increased the proline content (24%), catalase (42%), peroxidase (60%) and malondialdehyde activities (116%) over the two years of study. As a result of the drought stress, the seed yield (18%), relative water content (19.5%) and amount of photosynthetic pigments (chlorophyll and carotenoids) dropped significantly. However, the total phenolic and flavonoid contents showed no significant changes. Under drought stress, the highest seed yields were seen in the G50, G57, G54, G55 and G60 genotypes, while the lowest value was observed in the G16 genotype (94 g plant-1). According to the findings, when compared to the drought-sensitive genotypes, the drought-tolerant arugula genotypes were marked with higher levels of proline accumulation and antioxidant enzyme activity. Correlation analysis indicated the positive effects of peroxidase, catalase and proline on seed yield under drought conditions. These traits can be considered for the selection of drought-tolerant genotypes in breeding programs.

Phytochemical, Morphological, and Physiological Variation in Different Ajowan (Trachyspermum ammi L.) Populations as Affected by Salt Stress, Genotype × Year Interaction and Pollination System.

In the present research, 28 populations of ajowan (Trachyspermum ammi L.) were evaluated for agro-morphological traits and essential oil yield in two consecutive years. Then, selected ajowan populations from these two years were used for further morphophysiological and biochemical studies under different salinity levels (control, 60, 90, and 120 mM NaCl). The main components of the oil were thymol (32.7-54.29%), γ-terpinene (21.71-32.81%), and p-cymene (18.74-26.16%). Salt stress caused an increase in essential oil content in the Esfahfo and Qazvin populations. The highest total phenolic and flavonoid contents were found in the Arak population grown in 60 mM NaCl (183.83 mg TAE g-1 DW) and the Yazd population grown in 90 mM NaCl (5.94 mg QE g-1 DW). Moreover, the Yazd population exhibited the strongest antioxidant activity based on DPPH (IC50 = 1566 µg/mL) under 60 mM NaCl and the highest reducing power (0.69 nm) under 120 mM NaCl. The results revealed that low and moderate salt stress improves the phytochemicals of ajowan seeds, which are useful for pharmaceutical and food applications. In this research, some morphological traits, as well as essential oil yield, were evaluated in open pollinated versus self-pollinated plants. As a result, plant height, number of flowering branches, and crown diameter significantly decreased in some populations, while a significant increase was obtained for number of flowers per umbel and seed numbers per umbel. Finally, self-pollination of ajowan might provide new insights for further breeding programs to increase oil or thymol content in ajowan.

Characterization of fennel germplasm for physiological persistence and drought recovery: Association with biochemical properties.

In the perennial medicinal plant fennel (Foeniculum vulgare), persistence over years, production stability, and successful post-drought recovery are as important as plant productivity. Characterization of productivity, post-drought recovery, persistency and their association with phytochemical properties has not yet been performed in fennel. In this study, 64 fennel genotypes (from 23 different countries) from four subspecies/varieties including F. vulgare ssp. piperitum, F. vulgare var. vulgare and F. vulgare var. dulce and F. vulgare var. azoricum were evaluated in the field over four years (2015-2018), then was assessed for post-drought recovery over the next two years (2019-2020). High genotypic variation was observed among genotypes and subspecies. Based on the GC-MS analysis, trans-anethole (22.4-90.6%), estragole (2.1-25.8%), fenchone (4.9-19.8%), and limonene (0.5-11.9%) are major components in the essential oils of the studied germplasm. The highest persistence and the lowest average post-drought recovery belonged to ssp. piperitum. This subspecies also had the highest amount of limonene, fenchone, and estragole and the lowest amount of trans-anethole compared to other subspecies. The highest essential oil content and stability was observed in var. dulce. Seed yield and persistence were found to be negatively associated, suggesting that selection for more productivity may indirectly promote less persistent genotypes. Post-drought recovery was negatively associated with two main phytochemical compounds of essential oil, fenchone and estragole, but positively associated with trans-anethole. Persistence had negative correlation with estragole content. Results indicated that indirect selection for post-drought recovery and persistence may be possible through selection for phytochemical properties. The negative correlation between some essential oil components may indicate that some are isomers, which can limit the ability to select for certain combinations. Superior genotypes identified in this study can be used to construct populations for future studies and as parents of crosses to develop new varieties.

Genetic analysis and physiological relationships of drought response in fennel: Interaction with mating system.

The consequences of water deficit and its interaction with pollination system (deliberate selfing compared with open-pollination) on physiological, agronomic and phytochemical traits are not understood in fennel (Foeniculum vulgare Mill.). A research was started by creating selfed (S1) and half-sib (HS) families on a fennel germplasm in 2018. Populations were studied in the field, applying a normal and a water deficit condition during two years (2019-2020). Considerable genotypic variation was observed within S1 and HS families for all of the evaluated traits, demonstrating that selection for these traits would be successful. Consequences of water deficit were manifested as declined most of the traits; and significantly increased essential oil content, harvest index, and proline content, in both populations. Mandatory selfing reduced the performance of genotypes for most of the traits confirming the existence of inbreeding depression (ID) with higher values for plant dry weight, seed yield, essential oil content, and number of umbelets per umbel. In S1 population, some of the studied traits had higher heritability estimates under normal condition and some of them showed higher heritability under water deficit. Positive relationship between GCA and STI in OP population indicated that it is possible to identify genotypes having high values of combining ability and drought tolerance. Results of the present study suggest that physiological traits cannot be used as an indicator to distinguish drought-tolerant genotypes in S1 progenies, whereas in OP progenies Chl a, Chl b, TChl, CAR, PRO, and RWC, which had significant correlations with drought tolerance, may be used for this purpose. Based on the results contrasting genotypes were identified, which can be used to develop mapping populations for genome studies of drought tolerance and physiological traits of this species in future studies.

Comprehensive Research on Essential Oil and Phenolic Variation in Different Foeniculum vulgare Populations During Transition from Vegetative to Reproductive Stage.

Chemical composition and antioxidant activity of four fennel populations (England, Spain, Poland and Iran) were investigated during six developmental stages including two vegetative and four reproductive phases. In reproductive phase, the essential oil content of fruits decreased and the maximum content (5.9%) was obtained in immediate fruits. The essential oils were analyzed using GC/MS. trans-Anethole was the main component of the leaves and the fruits oil. In leaves, it ranged from 41.28% in England at late vegetative stage to 56.6% in Poland population at early vegetative stage. Other major compounds of leaves were limonene, α-pinene and (Z)-ß-ocimene. In reproductive phases the trans-anethole increased dramatically. It varied from 85.25% in immature fruits from Poland to 90.7% in pre-mature stage from Spain. The highest phenolic content in the extracts at different growth stages obtained 189 mg TAE/g DW at full mature stage of seed in Iran population. The flavonoid of leaves extract ranged from 3 to 7.5 mg QUE/g DW, while in fruits extract varied from 3 to 10.3 mg QUE/g DW. Antioxidant activity of the extracts was evaluated using 1,1-diphenyl-2-picrylhydrazy (DPPH) and ß-carotene model systems. Immature and full mature growth stages of fennel population from Spain indicated the highest activity in quenching of DPPH radical (74.2% and 74.5, respectively). Antioxidant activities of the extracts had high positive correlation with their phenolic contents in all fruit maturity stages. Finally, it might probably be suggested that in fennel the hot and humid condition can lead to increase trans-anethole, while the hot and dry one can produce higher amount of phenolics and flavonoids.

Inhibitory effect of different fennel (Foeniculum vulgare) samples and their phenolic compounds on formation of advanced glycation products and comparison of antimicrobial and antioxidant activities.

In this study, antioxidant, antibacterial and antiglycation properties of methanolic extracts of 23 fennel samples were evaluated and their major compounds were determined using HPLC analysis. The anti-glycative activity of extracts was evaluated in the bovine serum albumin (BSA)/glucose system. The level of glycation, conformational alterations and protein binding to RAGE receptors were assessed by Congo red binding assay and a brown staining method. Among samples, Kh1 from Iran possessed the highest TFC (14.8mgQUEg(-1)), TPC (262mg/g DW) and antioxidant activity (IC50=76µg/ml). The HPLC results revealed high variation in 23 fennel samples according to their major flavonoid (quercetin, apigenin and rutin) and phenolic (chlorogenic, caffeic and 1,5-dicaffeoylquinic acid) compounds. The antibacterial activity of methanolic extracts against four food-borne pathogens was also assessed. The seed extracts of Kh1 and En samples showed moderate to good inhibitory activities (MICs=62.5-125µg/ml) against three bacteria, as well as high anti-glycative activity.