Karina B. Ruiz

Quinoa biodiversity and sustainability for food security under climate change. A review

Climate change is rapidly degrading the conditions of crop production. For instance, increasing salinization and aridity is forecasted to increase in most parts of the world. As a consequence, new stress-tolerant species and genotypes must be identified and used for future agriculture. Stress-tolerant species exist but are actually underutilized and neglected. Many stress-tolerant species are indeed traditional crops that are only cultivated by farmers at a local scale. Those species have a high biodiversity value. Besides, the human population will probably reach nine billion within coming decades. To keep pace with population growth, food production must increase dramatically despite the limited availability of cultivable land and water. Here, we review the benefits of quinoa, Chenopodium quinoa Willd., a seed crop that has endured the harsh bioclimatic conditions of the Andes since ancient times. Although the crop is still mainly produced in Bolivia and Peru, agronomic trials and cultivation are spreading to many other countries. Quinoa maintains productivity on rather poor soils and under conditions of water shortage and high salinity. Moreover, quinoa seeds are an exceptionally nutritious food source, owing to their high protein content with all essential amino acids, lack of gluten, and high content of several minerals, e.g., Ca, Mg, Fe, and health-promoting compounds such as flavonoids. Quinoa has a vast genetic diversity resulting from its fragmented and localized production over the centuries in the Andean region, from Ecuador to southern Chile, and from sea level to the altiplano. Quinoa can be adapted to diverse agroecological conditions worldwide. Year 2013 has therefore been declared the International Year of Quinoa by the United Nations Food and Agriculture Organization. Here, we review the main characteristics of quinoa, its origin and genetic diversity, its exceptional tolerance to drought and salinity, its nutritional properties, the reasons why this crop can offer several ecosystem services, and the role of Andean farmers in preserving its agrobiodiversity. Finally, we propose a schematic model integrating the fundamental factors that should determine the future utilization of quinoa, in terms of food security, biodiversity conservation, and cultural identity.

Spermidine application to young developing peach fruits leads to a slowing down of ripening by impairing ripening-related ethylene and auxin metabolism and signaling.

Peach (Prunus persica var. laevis Gray) was chosen to unravel the molecular basis underlying the ability of spermidine (Sd) to influence fruit development and ripening. Field applications of 1 mM Sd on peach fruit at an early developmental stage, 41 days after full bloom (dAFB), i.e. at late stage S1, led to a slowing down of fruit ripening. At commercial harvest (125 dAFB, S4II) Sd-treated fruits showed a reduced ethylene production and flesh softening. The endogenous concentration of free and insoluble conjugated polyamines (PAs) increased (0.3-2.6-fold) 1 day after treatment (short-term response) butsoon it declined to control levels; starting from S3/S4, when soluble conjugated forms increased (up to five-fold relative to controls at ripening), PA levels became more abundant in treated fruits, (long-term response). Real-time reverse transcription-polymerase chain reaction analyses revealed that peaks in transcript levels of fruit developmental marker genes were shifted ahead in accord with a developmental slowing down. At ripening (S4I-S4II) the upregulation of the ethylene biosynthetic genes ACO1 and ACS1 was dramatically counteracted by Sd and this led to a strong downregulation of genes responsible for fruit softening, such as PG and PMEI. Auxin-related gene expression was also altered both in the short term (TRPB) and in the long term (GH3, TIR1 and PIN1), indicating that auxin plays different roles during development and ripening processes. Messenger RNA amounts of other hormone-related ripening-regulated genes, such as NCED and GA2-OX, were strongly downregulated at maturity. Results suggest that Sd interferes with fruit development/ripening by interacting with multiple hormonal pathways.

Quinoa – a Model Crop for Understanding Salt-tolerance Mechanisms in Halophytes

Quinoa (Chenopodium quinoa Willd.) is an ancient Andean crop that produces edible seeds and leaves. Quinoas tolerance to salinity and other types of abiotic stresses provides it with high potential in a world where scarcity of water and increased soil salinization are important causes of crop failures. Due to its traditionally broad cultivation area (from Colombia to southern Chile), there is a wide range of quinoa cultivars adapted to specific conditions displaying a broad genetic variability in stress tolerance. In addition, being practically unique as a halophytic seed-producing crop with amazing nutritional properties, it is ideal as a model species for investigating morphological, cellular, physiological, and bio-molecular mechanisms of salinity tolerance. This review summarizes current knowledge of genotype-dependent variability in salinity responses and adaptive salt-tolerance mechanisms in quinoa. These include anatomical features and physiological aspects, such as osmotic adjustment through accumulation of ions, osmoprotectants, and sodium loading, transport, and storage, including the activity and gene expression of plasma and vacuolar membrane transporters. Finally, current knowledge regarding the effect of salinity on the nutritional properties of quinoa is discussed.

Ethylene and auxin biosynthesis and signaling are impaired by methyl jasmonate leading to a transient slowing down of ripening in peach fruit

Peach (Prunus persica) was chosen as a model to further clarify the physiological role of jasmonates (JAs) during fruit ripening. To this aim, the effect of methyl jasmonate (MJ, 0.88 mM), applied at a late stage (S3) of fruit development under field conditions (in planta), on the time-course of fruit ripening over a 14-day period was evaluated. As revealed by a non-destructive device called a DA-meter, exogenously applied MJ impaired the progression of ripening leading to less ripe fruit at harvest. To better understand the molecular basis of MJ interference with ripening, the time-course changes in the expression of ethylene-, cell wall-, and auxin-related genes as well as other genes (LOX, AOS and bZIP) was evaluated in the fruit mesocarp. Real-time PCR analyses revealed that transcript levels of ethylene-related genes were strongly affected. In a first phase (days 2 and/or 7) of the MJ response, mRNAs of the ethylene biosynthetic genes ACO1, ACS1 and the receptor gene ETR2 were strongly but transiently down-regulated, and then returned to or above control levels in a second phase (days 11 and/or 14). Auxin biosynthetic, conjugating, transport and perception gene transcripts were also affected. While biosynthetic genes (TRPB and IGPS) were up-regulated, auxin-conjugating (GH3), perception (TIR1) and transport (PIN1) genes were transiently but strongly down-regulated in a first phase, but returned to control levels subsequently. Transcript levels of two JA-related genes (LOX, AOS) and a developmentally regulated transcription factor (bZIP) were also affected, suggesting a shift ahead of the ripening process. Thus, in peach fruit, the transient slowing down of ripening by exogenous MJ was associated with an interference not only with ethylene but also with auxin-related genes.

New Insight into Quinoa Seed Quality under Salinity: Changes in Proteomic and Amino Acid Profiles, Phenolic Content, and Antioxidant Activity of Protein Extracts

Quinoa (Chenopodium quinoa Willd) is an ancient Andean seed-producing crop well known for its exceptional nutritional properties and resistance to adverse environmental conditions, such as salinity and drought. Seed storage proteins, amino acid composition, and bioactive compounds play a crucial role in determining the nutritional value of quinoa. Seeds harvested from three Chilean landraces of quinoa, one belonging to the salares ecotype (R49) and two to the coastal-lowlands ecotype, VI-1 and Villarrica (VR), exposed to two levels of salinity (100 and 300 mM NaCl) were used to conduct a sequential extraction of storage proteins in order to obtain fractions enriched in albumins/globulins, 11S globulin and in prolamin-like proteins. The composition of the resulting protein fractions was analyzed by one- and two-dimensional polyacrylamide gel electrophoresis. Results confirmed a high polymorphism in seed storage proteins; the two most representative genotype-specific bands of the albumin/globulin fraction were the 30- and 32-kDa bands, while the 11S globulin showed genotype-specific polymorphism for the 40- and 42-kDa bands. Spot analysis by mass spectrometry followed by in silico analyses were conducted to identify the proteins whose expression changed most significantly in response to salinity in VR. Proteins belonging to several functional categories (i.e., stress protein, metabolism, and storage) were affected by salinity. Other nutritional and functional properties, namely amino acid profiles, total polyphenol (TPC) and flavonoid (TFC) contents, and antioxidant activity (AA) of protein extracts were also analyzed. With the exception of Ala and Met in R49, all amino acids derived from protein hydrolysis were diminished in seeds from salt-treated plants, especially in landrace VI-1. By contrast, several free amino acids were unchanged or increased by salinity in R49 as compared with VR and VI-1, suggesting a greater tolerance in the salares landrace. VR had the highest TPC and AA under non-saline conditions. Salinity increased TPC in all three landraces, with the strongest increase occurring in R49, and enhanced radical scavenging capacity in R49 and VR. Overall, results show that salinity deeply altered the seed proteome and amino acid profiles and, in general, increased the concentration of bioactive molecules and AA of protein extracts in a genotype-dependent manner.