Abstract
BackgroundHAK/KUP/KT (High-affinity K+ transporters/K+ uptake permeases/K+ transporters) is the largest potassium transporter family in plants, and plays pivotal roles in K+ uptake and transport, as well as biotic and abiotic stress responses. However, our understanding of the gene family in barley (Hordeum vulgare L.) is quite limited.ResultsIn the present study, we identified 27 barley HAK/KUP/KT genes (hereafter called HvHAKs) through a genome-wide analysis. These HvHAKs were unevenly distributed on seven chromosomes, and could be phylogenetically classified into four clusters. All HvHAK protein sequences possessed the conserved motifs and domains. However, the substantial difference existed among HAK members in cis-acting elements and tissue expression patterns. Wheat had the most orthologous genes to barley HAKs, followed by Brachypodium distachyon, rice and maize. In addition, six barley HAK genes were selected to investigate their expression profiling in response to three abiotic stresses by qRT-PCR, and their expression levels were all up-regulated under salt, hyperosmotic and potassium deficiency treatments.ConclusionTwenty seven HAK genes (HvHAKs) were identified in barley, and they differ in tissue expression patterns and responses to salt stress, drought stress and potassium deficiency.
Highlights
HAK/KUP/KT (High-affinity K+ transporters/K+ uptake permeases/K+ transporters) is the largest potassium transporter family in plants, and plays pivotal roles in K+ uptake and transport, as well as biotic and abiotic stress responses
HAK genes in barley were named in the order of their locations on chromosomes, and no tandem duplication event was observed (Table 1; Additional file 2)
The theoretical molecular weights (MW) of HvHAK proteins were in the range of 79.93 to 98.04 kDa
Summary
HAK/KUP/KT (High-affinity K+ transporters/K+ uptake permeases/K+ transporters) is the largest potassium transporter family in plants, and plays pivotal roles in K+ uptake and transport, as well as biotic and abiotic stress responses. Potassium (K) is the second most abundant mineral nutrient in plants, comprising 2–10% of plant dry weight [1]. K is essential for plants to maintain normal physiological and biochemical processes such as stomatal movement, photosynthesis, osmoregulation, protein synthesis, enzyme activation, and involved in the responses to biotic and abiotic stresses [2, 3]. K for plants is commonly quite low due to the strong K adsorption by 2:1 silicate minerals [4]. K concentration in plants differs greatly between species, tissues, and cell organs
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