Chen Xiaolei, Shao Yongchun, Jiang Yi, Seung David, Guzmán Carlos, Xu Qiang, Zhang Yazhou, Chen Qian, Tang Huaping, Qi Pengfei, Deng Mei, Ma Jian, Chen Guoyue, Wang Jirui, Wei Yuming, Zheng Youliang, Jiang Qiantao
State Key Laboratory of Crop Gene Exploration and Utilization in Southwest China, Sichuan Agricultural University, Chengdu, China.
Triticeae Research Institute, Sichuan Agricultural University, Chengdu, China.
J Sci Food Agric. 2025 Mar 15;105(4):2332-2341. doi: 10.1002/jsfa.14003. Epub 2024 Nov 6.
Amylose has a major influence over starch properties and end-use quality in wheat. The granule-bound starch synthase I, encoded by Wx-1, is the single enzyme responsible for amylose synthesis. Natural null mutants of Wx-1 appear at extremely low frequencies, particularly in the Wx-D1 locus, where only four spontaneous null variants have been identified, with different geographic origins. The current study identified an induced Wx-D1 null mutant (M4-9484) from the M generation of an ethyl methanesulfonate-mutagenized population of wheat cv. 'SM126'.
The sequencing showed that the complete Wx-D1 ORF sequences of 'SM126' and M4-9484 were 2862 bp long and that there was one SNP mutation between them. The mutation was located at the RNA splice site within the junction of exon 8 and intron 8, which led to abnormal transcription of Wx-D1, with five different aberrant transcripts being identified in the mutant. The Wx-D1 null allele resulted in amylose and total starch content being decreased in M4-9484 in comparison with the wild-type 'SM126', with higher swelling capacity and being fully pasted at higher temperatures than the wild-type parent.
The mutation of the Wx-D1 null gene affects the formation of amylose directly, resulting in significantly altered starch properties. This discovery offers valuable insights for enhancing wheat starch quality and contributes to the diversification of starch characteristics. It also deepens our understanding of the genetic and molecular mechanisms underlying amylose synthesis, thereby supporting breeding programs. © 2024 Society of Chemical Industry.
直链淀粉对小麦淀粉特性和最终用途品质有重大影响。由Wx - 1编码的颗粒结合型淀粉合酶I是负责直链淀粉合成的唯一酶。Wx - 1的天然缺失突变体出现频率极低，尤其是在Wx - D1位点，在该位点仅鉴定出四个具有不同地理起源的自发缺失变体。本研究从甲基磺酸乙酯诱变的小麦品种‘SM126’的M代群体中鉴定出一个诱导型Wx - D1缺失突变体（M4 - 9484）。
测序表明，‘SM126’和M4 - 9484的完整Wx - D1开放阅读框序列长度均为2862 bp，且二者之间存在一个单核苷酸多态性（SNP）突变。该突变位于外显子8和内含子8交界处的RNA剪接位点，导致Wx - D1转录异常，在突变体中鉴定出五种不同的异常转录本。与野生型‘SM126’相比，Wx - D1缺失等位基因导致M4 - 9484中的直链淀粉和总淀粉含量降低，溶胀能力更高，并且在比野生型亲本更高的温度下完全糊化。
Wx - D1缺失基因的突变直接影响直链淀粉的形成，导致淀粉特性发生显著改变。这一发现为提高小麦淀粉品质提供了有价值的见解，并有助于淀粉特性的多样化。它还加深了我们对直链淀粉合成的遗传和分子机制的理解，从而支持育种计划。© 2024化学工业协会。
