Genetic Diversity and Physiological Performance of Portuguese Wild Beet (Beta vulgaris spp. maritima) from Three Contrasting Habitats

Abstract

The establishment of stress resilient sugar beets (Beta vulgaris spp. vulgaris) is an important breeding goal since this cash crop is susceptible to drought and salinity. The genetic diversity in cultivated sugar beets is low and the beet wild relatives are useful genetic resources for tolerance traits. Three wild beet populations (Beta vulgaris spp. maritima) from contrasting environments, Vaiamonte (VMT, dry inland hill), Comporta (CMP, marsh) and Oeiras (OEI, coastland), and one commercial sugar beet (Isella variety, SB), are compared. At the genetic level, the use of six microsatellite allowed to detect a total of seventy six alleles. It was observed that CMP population has the highest value concerning the effective number of alleles and of expected heterozygosity. By contrast, sugar beet has the lowest values for all the parameters considered. Loci analysis with STRUCTURE allows defining three genetic clusters, the sea beet (OEI and CMP), the inland ruderal beet (VMT) and the sugar beet (SB). A screening test for progressive drought and salinity effects demonstrated that: all populations were able to recover from severe stress; drought impact was higher than that from salinity; the impact on biomass (total, shoot, root) was population specific. The distinct strategies were also visible at physiological level. We evaluated the physiological responses of the populations under drought and salt stress, namely at initial stress stages, late stress stages, and early stress recovery. Multivariate analysis showed that the physiological performance can be used to discriminate between genotypes, with a strong contribution of leaf temperature and leaf osmotic adjustment. However, the separation achieved and the groups formed are dependent on the stress type, stress intensity and duration. Each of the wild beet populations evaluated is very rich in genetic terms (allelic richness) and exhibited physiological plasticity, i.e., the capacity to physiologically adjust to changing environments. These characteristics emphasize the importance of the wild beet ecotypes for beet improvement programs. Two striking ecotypes are VMT, which is the best to cope with drought and salinity, and CMP which has the highest root to shoot ratio. These genotypes can supply breeding programs with distinct goals.

Edible halophytes of the Mediterranean basin: Potential candidates for novel food products

“…maritima (L.) Arcang.) belongs to the Chenopodiaceae family and is a wild relative of cultivated beets (B. vulgaris) which thrives in salt marshes and seashore cliffs and exhibits high salt-stress tolerance (Ribeiro et al, 2016) (Fig. 3a).…”

“…3a). In a recent study, Ribeiro et al (2016) observed that sea beet populations from contrasting environments showed physiological plasticity and recovered from severe stress conditions (drought and salinity stress), while Skorupa et al (2016) reported that several genes related with carbon fixation, biosynthesis of ribosomes and expansion and formation of cell walls are involved in salt tolerance. The edible parts of the plant are its leaves and leaf stems which are eaten as cooked or raw greens throughout the Mediterranean basin (Turner et al, 2011).…”

Ensuring Food Security of Arid Regions through Sustainable Cultivation of Halophytes

“…belongs to the family of Chenopodiaceae. It grows in salt marshes, exhibits high salt-stress tolerance, and can endure harsh conditions (Ribeiro et al 2016). Its leaves and stem are used as food after cooking or raw greens in different regions (Turner et al 2011).…”

Opportunities and Limitations of Crop Phenotyping in Southern European Countries

“…In Portugal, phenotyping research targets are focused on both model species and crops, at the molecular/cellular level and at the whole-plant level. However, it is still predominantly low-throughput phenotyping, based for example on leaf gas exchange (Cruz de Carvalho et al, 2011; Ribeiro et al, 2016) or thermography (Costa et al, 2016) and medium-throughput phenotyping utilizing rapid chl a fluorescence induction transients (Silvestre et al, 2014). Portugal lacks a phenotyping network and HTPP infrastructures capable of supporting rapid speed characterization of relevant crop traits (e.g., growth, yield, quality, stress resilience).…”