BackgroundNitrogen (N) is the most common limiting factor for crop productivity worldwide. An effective approach to solve N deficiency is to develop low N (LN) tolerant crop cultivars. Tibetan annual wild barley is well-known for its wide genetic diversity and high tolerance to poor soil fertility. Up to date, no study has been done to illustrate the mechanism of LN tolerance underlying the wild barley at transcriptional level.ResultsIn this study, we employed Illumina RNA-Sequencing to determine the genotypic difference in transcriptome profile using two Tibetan wild barley genotypes differing in LN tolerance (XZ149, tolerant and XZ56, sensitive). A total of 1469 differentially expressed genes (DEGs) were identified in the two genotypes at 6 h and 48 h after LN treatment. Genetic difference existed in DEGs between XZ149 and XZ56, including transporters, transcription factors (TFs), kinases, antioxidant stress and hormone signaling related genes. Meanwhile, 695 LN tolerance-associated DEGs were mainly mapped to amino acid metabolism, starch and sucrose metabolism and secondary metabolism, and involved in transporter activity, antioxidant activities, and other gene ontology (GO). XZ149 had a higher capability of N absorption and use efficiency under LN stress than XZ56. The higher expression of nitrate transporters and energy-saving assimilation pattern could be attributed to its more N uptake and higher LN tolerance. In addition, auxin (IAA) and ethylene (ETH) response pathways may be also related to the genotypic difference in LN tolerance.ConclusionThe responses of XZ149 and XZ56 to LN stress differed dramatically at transcriptional level. The identified candidate genes related to LN tolerance may provide new insights into comprehensive understanding of the genotypic difference in N utilization and LN tolerance.Electronic supplementary materialThe online version of this article (doi:10.1186/s12870-016-0721-8) contains supplementary material, which is available to authorized users.

No abstract

No abstract

BackgroundPotassium (K) deficiency in arable land is one of the most important factors affecting crop productivity. Development of low K (LK) tolerant crop cultivars is regarded as a best economic and effective approach for solving the issue of LK. In previous studies, we found a wider variation of LK tolerance in the Tibetan wild barley accessions than cultivated barley. However, the mechanism of LK tolerance in wild barley is still elusive.ResultsIn this study, two wild barley genotypes (XZ153, LK tolerant and XZ141, LK sensitive) and one cultivar (LuDaoMai, LK tolerant) was used to investigate metabolome changes in response to LK stress. Totally 57 kinds of metabolites were identified in roots and leaves of three genotypes at 16 d after LK treatment. In general, accumulation of amino acids and sugars was enhanced in both roots and leaves, while organic acids were reduced under LK stress compared to the control. Meanwhile, the concentrations of the negatively charged amino acids (Asp and Glu) and most organic acids was reduced in both roots and leaves, but more positively charged amino acids (Lys and Gln) were increased in three genotypes under LK. XZ153 had less reduction than other two genotypes in biomass and chlorophyll content under LK stress and showed greater antioxidant capacity as reflected by more synthesis of active oxygen scavengers. Higher LK tolerance of XZ153 may also be attributed to its less carbohydrate consumption and more storage of glucose and other sugars, thus providing more energy for plant growth under LK stress. Moreover, phenylpropanoid metabolic pathway mediated by PAL differed among three genotypes, which is closely associated with the genotypic difference in LK tolerance.ConclusionsLK tolerance in the wild barley is attributed to more active phenylpropanoid metabolic pathway mediated by PAL, energy use economy by reducing carbohydrate consumption and storage of glucose and other sugars, and higher antioxidant defense ability under LK stress.Electronic supplementary materialThe online version of this article (10.1186/s12870-018-1404-4) contains supplementary material, which is available to authorized users.

No abstract