Evaluation of corm origin and climatic conditions on saffron (Crocus sativus L.) yield and quality

BACKGROUND

Crocus sativus L. is an autumn-flowering geophyte belonging to the Iridaceae family, known for the medicinal and coloring uses of the spice from its dried stigmas. It is cultivated in countries with different pedoclimatic conditions. This paper reports on a two-year research project carried out in the Basilicata region of southern Italy on the question of how to obtain the highest performance from saffron. It considers corms from three different geographical origins - 'Sardinia', 'Abruzzo' and 'Kozani' at three different cultivation sites, namely Castelgrande (40° 46' N, 15° 26' E, 781 m a.s.l.), Genzano di Lucania (40° 50' N, 16° 08' E, 344 m a.s.l.), and Villa d'Agri (40° 22' N, 15° 48' E, 638 m a.s.l.).

RESULTS

The highest yields were obtained in the second year by the combination of 'Genzano di L. × Sardinia' and 'Castelgrande × Abruzzo' with 28.1 and 23.9 kg ha^-1 of dried stigma, respectively. Saffron quality was determined according to ISO 3632, which classifies the samples into three categories depending on the crocin, picrocrocin, and safranal content. Results highlighted that the highest values for coloring (242.1) and bitterness (97.7) were achieved in Genzano di L. during 2013. Moreover, the crocins were correlated positively with stigma yield and air mean temperature but negatively with safranal.

CONCLUSION

This study demonstrated, through principal component analysis (PCA), that the cultivation site with higher air temperature and without excessive rain during the flowering period generated the best stigma yield with high-quality traits. © 2019 Society of Chemical Industry.

Pharmacokinetic Properties of Saffron and its Active Components

Saffron as a medicinal plant has many therapeutic effects. Phytochemical studies have reported that saffron is composed of at least four active ingredients which include crocin, crocetin, picrocrocin and safranal. The carotenoids of saffron are sensitive to oxygen, light, heat and enzymatic oxidization. However, regulation of these factors is required for saffron quality. Some pharmacologic effects of saffron and its active compounds include cardioprotective, neuroprotective, memory enhancer, antidepressant and anxiolytic. Among more than 150 chemicals of saffron, the most biologically active components are two carotenoids including crocin and crocetin. Most of the pharmacokinetic studies are related to these compounds. The pharmacokinetic studies have shown that crocin is not available after oral administration in blood circulation. Crocin is converted to crocetin in intestine but after intravenous injection, the level of crocetin in plasma is low. Crocetin can distribute in different tissues because of weak interaction between crocetin and albumin. Also it can penetrate blood-brain barrier and reach CNS by passive transcellular diffusion; thus it can be effective in neurodegenerative disorders. The large portion of crocin is eliminated via feces.

Saffron: Its Phytochemistry, Developmental Processes, and Biotechnological Prospects

The present state of knowledge concerning developmental processes and the secondary metabolism of saffron, Crocus sativus L. (Iridaceae), along with the genes involved in these processes so far known, is reviewed. Flowers and corms constitute the most valuable parts of saffron. Corm and flower development are two key aspects to be studied in saffron to increase the yield and quality of the spice, to raise its reproductive rate, and to implement new production systems. Important knowledge about the physiology of flowering and vegetative growth has been acquired in recent years, but there is still only limited information on molecular mechanisms controlling these processes. Although some genes involved in flower formation and meristem transition in other species have been isolated in saffron, the role of these genes in this species awaits further progress. Also, genes related with the synthesis pathway of abscisic acid and strigolactones, growth regulators related with bud endodormancy and apical dominance (paradormancy), have been isolated. However, the in-depth understanding of these processes as well as of corm development is far from being achieved. By contrast, saffron phytochemicals have been widely studied. The different flower tissues and the corm have been proved to be an important source of phytochemicals with pharmacological properties. The biotechnological prospects for saffron are here reviewed on the basis of the discovery of the enzymes involved in key aspects of saffron secondary metabolism, and we also analyze the possibility of transferring current knowledge about flowering and vegetative propagation in model species to the Crocus genus.

Implications of carotenoid biosynthetic genes in apocarotenoid formation during the stigma development of Crocus sativus and its closer relatives

Crocus sativus is a triploid sterile plant characterized by its long red stigmas, which produce and store significant quantities of the apocarotenoids crocetin and crocin, formed from the oxidative cleavage of zeaxanthin. Here, we investigate the accumulation and the molecular mechanisms that regulate the synthesis of these apocarotenoids during stigma development in C. sativus. We cloned the cDNAs for phytoene synthase, lycopene-beta-cyclase, and beta-ring hydroxylase from C. sativus. With the transition of yellow undeveloped to red fully developed stigmas, an accumulation of zeaxanthin was observed, accompanying the expression of CsPSY, phytoene desaturase, and CsLYCb, and the massive accumulation of CsBCH and CsZCD transcripts. We analyzed the expression of these two transcripts in relation to zeaxanthin and apocarotenoid accumulation in other Crocus species. We observed that only the relative levels of zeaxanthin in the stigma of each cultivar were correlated with the level of CsBCH transcripts. By contrast, the expression levels of CsZCD were not mirrored by changes in the apocarotenoid content, suggesting that the reaction catalyzed by the CsBCH enzyme could be the limiting step in the formation of saffron apocarotenoids in the stigma tissue. Phylogenetic analysis of the CsBCH intron sequences allowed us to determine the relationships among 19 Crocus species and to identify the closely related diploids of C. sativus. In addition, we examined the levels of the carotenoid and apocarotenoid biosynthetic genes in the triploid C. sativus and its closer relatives to determine whether the quantities of these specific mRNAs were additive or not in C. sativus. Transcript levels in saffron were clearly higher and nonadditive, suggesting that, in the triploid gene, regulatory interactions that produce novel effects on carotenoid biosynthesis genes are involved.