Exploring the role of carbon and nitrogen metabolism in Chenopodium quinoa (Willd.) from the commencement of grain growth until maturity

Abstract

Co-ordination between carbon and nitrogen metabolism plays a vital role in maintaining the source-sink relationship between the reproductive structures (inflorescence and seed). The present investigation was carried out to study carbon and nitrogen metabolism in quinoa genotypes IC411824, IC411825, EC507747 and EC507742 at different stages of anthesis and post -anthesis, which could affect seed growth and maturity. Carbon metabolism enzymes such as acid invertase, sucrose synthase (cleavage), and sucrose phosphate synthase showed increased activity from 75 to 90 days after sowing (DAS) in inflorescence of quinoa genotypes, which might be responsible for the assimilation of carbohydrates required for seed development during the post-anthesis period. Activities of acid invertase and sucrose synthase (cleavage) were observed to be maximum in seeds of quinoa genotypes at 110 DAS, then decreased as seed development progressed, reaching a minimum near seed maturity at 124 DAS. Nitrogen metabolizing enzymes such as glutamate dehydrogenase and nitrite reductase plays a central role in the re- assimilation of amides from the amino group of asparginase at 90 DAS in inflorescence and 124 DAS at seed maturity. IC411825 and EC507747 genotypes had better availability to assimilate the nutrients and their remobilization during the onset of seed development. The pattern of carbon and nitrogen metabolism enzymes at different stages of inflorescence and grain development influenced the source sink relationship mediating partitioning and accumulation of assimilates during of anthesis and post anthesis periods of grain development in quinoa, which eventually led to grain development and yield establishment.