MtEIN2 affects nitrate uptake and accumulation of photosynthetic pigments under phosphate and nitrate deficiency in Medicago truncatula.

Abstract

Ethylene (ET) controls many facets of plant growth and development under abiotic and biotic stresses. MtEIN2, as a critical element of the ET signalling pathway, is essential in biotic interactions. However, the role of MtEIN2 in responding to abiotic stress, such as combined nutrient deficiency, is less known. To assess the role of ethylene signalling in nutrient uptake, we manipulated nitrate (NO3 - ) and phosphate (Pi) availability for wild type (WT) and the ethylene-insensitive (MtEIN2-defective) mutant, sickle, in Medicago truncatula. We measured leaf biomass and photosynthetic pigments in WT and sickle to identify conditions leading to different responses in both genotypes. Under combined NO3 - and Pi deficiency, sickle plants had higher chlorophyll and carotenoid contents than WT plants. Under these conditions, nitrate content and gene expression levels of nitrate transporters were higher in the sickle mutant than in the WT. This led to the conclusion that MtEIN2 is associated with nitrate uptake and the content of photosynthetic pigments under combined Pi and NO3 - deficiency in M. truncatula. We conclude that ethylene perception plays a critical role in regulating the nutrient status of plants. This article is protected by copyright. All rights reserved.