Isolation and expression of a new gene <italic>HvMEL1 AGO</italic> in Tibetan hulless barley under leaf stripe stress

Abstract

<p id="C3">To explore <italic>AGO</italic> genes related to leaf stripe in Tibetan hulless barley (BLS), we obtained a differentially expressed <italic>HvMEL1 AGO </italic>gene from the transcriptional sequencing in normal and diseased leaves from resistant Tibetan hulless barley variety Kunlun 14 and the susceptible variety 1141. The <italic>HvMEL1 AGO</italic> gene was 3462 bp in length, of which the CDS (coding domain sequence) was 100% consistent in Kunlun 14 and 1141 varieties. The length of <italic>HvMEL1 AGO</italic> gene was 3161 bp without intron, contained a 3129 bp open reading frame, encoded 1043 amino acids, had a theoretical isoelectric point of 9.33, and has a predicted molecular weight of 115,865.58 Da. Protein sequence analysis showed that HvMEL1 AGO was a hydrophilic unstable acidic protein with highly conserved structural domains of DUF1785, PAZ and PIWI, belonging to <italic>AGO</italic> gene family. Phylogenetic tree analysis showed that HvMEL1 AGO belonged to the AGO1 class in <italic>Arabidopsis</italic> AGO family phylogenetic tree with HvAGO12, HvAGO18, HvAGO1D and HvAGO1B in barley AGO family, and were closely related to HvAGO12. The predicted protein interactions showed that the known proteins that acted closely with MEL1 in rice were the DCL classes, DCL1, DCL2A, DCL3A, DCL3B and DCL4, respectively. Semi-quantitative and quantitative PCR results indicated that the relative expression levels of <italic>HvMEL1 AGO</italic> gene were significantly down-regulated in 1141 and Kunlun 14 under BLS. We hypothesized that <italic>HvMEL1 AGO</italic> gene played an important role in the streak resistance mechanism of barley. This study lays the foundation for exploring the role and regulatory mechanism of <italic>HvMEL1 AGO</italic> in the process of BLS resistance.