Seed characterization and early Nitrogen metabolism performance of seedlings from Altiplano and Coastal ecotypes of Quinoa

• DOI: 10.21203/rs.2.24363/v2
• Publication Date: 2020-06-29T18:42:49Z
• Authors: Katherine Pinto/I...; Teodoro Coba de l...; Enrique Ostria-Ga...; Cristian Ibanez; Vilbett Vriones; Alexander Vergara; Rodrigo Alvarez; Catalina Castro; Carolina Sanhueza; Patricio Castro; Luisa Bascunan-Godoy
• Keywords: 0301 basic medicine; Nitrate-sensing; Nitrogen; Anion Transport Proteins; Germination; Nitrate Reductase; Plant Roots; Glutamine synthetase; 03 medical and health sciences; Gene Expression Regulation, Plant; Glutamate-Ammonia Ligase; Photochemical process; Crop yield; Nitrogen metabolism; Chenopodium quinoa; Chile; Agricultural Science; Phylogeny; Plant Proteins; 580; Ecotype; 2. Zero hunger; Nitrates; Botany; Proteins; Nitrate Transporters; 15. Life on land; Nitrate transporters; Seedlings; QK1-989; Seeds; N transport; Chlorophyll fluorescence; Nitrate reductase; Research Article

Abstract Background: Early seed germination and a functional root system development during establishment are crucial attributes contributing to nutrient competence under marginal nutrient soil conditions. Chenopodium quinoa Willd (Chenopodiaceae) is a rustic crop, able to grow in marginal areas. Altiplano and Coastal/Lowlands are two representative zones of quinoa cultivation in South America with contrasting soil fertility and edaphoclimatic conditions. In the present work, we hypothesize that the ecotypes of Quinoa from Altiplano (landrace Socaire) and from Coastal/Lowland (landrace Faro) have developed differential adaptive responses in order to survive under conditions of low availability of N in their respective climatic zones of Altiplano and Lowlands. In order to understand intrinsic differences for N competence between landraces, seed metabolite profile and germinative capacity were studied. Additionally, in order to elucidate the mechanisms of N uptake and assimilation at limiting N conditions during establishment, germinated seeds of both landraces were grown at either sufficient nitrate (HN) or low nitrate (LN) supply. We studied the photosynthetic performance, protein storage, root morphometrical parameters, activity and expression of N-assimilating enzymes, and the expression of nitrate transporters of roots in plants submitted to the different treatments. Results: Seeds from Socaire landrace presented higher content of free N-related metabolites and faster seed germination rate compared to Faro landrace. Seedlings of both ecotypes presented similar physiological performance at HN supply, but at LN supply their differences were exalted. At LN, Socaire plants showed an increased root biomass (including a higher number and total length of lateral roots), a differential regulation of a nitrate transporter (a NPF6.3 -like homologue) belonging to the Low Affinity Transport System (LATS), and an upregulation of a nitrate transporter (a NRT2.1 -like homologue) belonging to the High Affinity nitrate Transport System (HATS) compared to Faro. These responses as a whole could be linked to a higher amount of stored proteins in leaves, associated to an enhanced photochemical performance in Altiplano plants, in comparison to Lowland quinoa plants. Conclusions: These differential characteristics of Socaire over Faro plants could involve an adaptation to enhanced nitrate uptake under the brutal unfavorable climate conditions of Altiplano.