AUTHOR=Feng Xiuqin , Rahman Md. Mostafijur , Hu Qian , Wang Bang , Karim Hassan , Guzmán Carlos , Harwood Wendy , Xu Qiang , Zhang Yazhou , Tang Huaping , Jiang Yunfeng , Qi Pengfei , Deng Mei , Ma Jian , Lan Jingyu , Wang Jirui , Chen Guoyue , Lan Xiujin , Wei Yuming , Zheng Youliang , Jiang Qiantao TITLE=HvGBSSI mutation at the splicing receptor site affected RNA splicing and decreased amylose content in barley JOURNAL=Frontiers in Plant Science VOLUME=13 YEAR=2022 URL=https://www.frontiersin.org/journals/plant-science/articles/10.3389/fpls.2022.1003333 DOI=10.3389/fpls.2022.1003333 ISSN=1664-462X ABSTRACT=

Granule-bound starch synthase I (HvGBSSI) is encoded by the barley waxy (Wx-1) gene and is the sole enzyme in the synthesis of amylose. Here, a Wx-1 mutant was identified from an ethyl methane sulfonate (EMS)-mutagenized barley population. There were two single-base mutations G1086A and A2424G in Wx-1 in the mutant (M2-1105). The G1086A mutation is located at the 3′ splicing receptor (AG) site of the fourth intron, resulting in an abnormal RNA splicing. The A2424G mutation was a synonymous mutation in the ninth intron. The pre-mRNA of Wx-1 was incorrectly spliced and transcribed into two abnormal transcripts. The type I transcript had a 6 bp deletion in the 5′ of fifth exon, leading to a translated HvGBSSI protein lacking two amino acids with a decreased starch-binding capacity. In the type II transcript, the fourth intron was incorrectly cleaved and retained, resulting in the premature termination of the barley Wx-1 gene. The mutations in the Wx-1 decreased the enzymatic activity of the HvGBSSI enzyme and resulted in a decreased level in amylose content. This work sheds light on a new Wx-1 gene inaction mechanism.