Journal of Integrative Agriculture

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全基因组关联和基因共表达分析发掘ZmMYB71调控玉米籽粒淀粉合成

  

  • 修回日期:2024-03-25

Genome-wide association and co-expression uncovered ZmMYB71 controls kernel starch content in maize

Jienan Han1, Ran Li1, Ze Zhang1, 2, Shiyuan Liu1, Qianqian Liu1, Zhennan Xu1, Zhiqiang Zhou 1, Xin Lu1, Xiaochuan Shangguan1, 2, Tingfang Zhou1, 2, Jianfeng Weng1, Zhuanfang Hao1, Degui Zhang1, Hongjun Yong1, Jingyu Xu2, Mingshun Li1#, Xinhai Li1, 2#   

  1. 1 Institute of Crop Science, Chinese Academy of Agricultural Science/State Key Laboratory of Crop Gene Resources and Breeding, Beijing 100081, China

    2 College of Agriculture, Heilongjiang Bayi Agricultural University, Daqing 163319, China

  • Revised:2024-03-25
  • About author:#Correspondence Mingshun Li, Email: limingshun@caas.cn; Xinhai Li, E-mail: lixinhai@caas.cn

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摘要： 淀粉是籽粒的主要贮藏物质，对玉米（Zea mays L.）的产量和品质至关重要。为满足未来粮食生产需求，了解玉米籽粒淀粉含量（SC）自然变异的遗传基础对于玉米育种意义重大。通过全基因组关联分析（GWAS），基于2年籽粒SC表型值分别发现84个和96个显著关联位点，关联区间包含185个候选基因。其中，ZmMYB71编码MYB转录因子，与淀粉合成基因共表达频数表现最高。本研究表明ZmMYB71是定位于细胞核的转录抑制因子，突变体籽粒SC增加幅度大于2.32%，但直链淀粉含量或百粒重基本不受影响。相较于野生型，zmmyb71突变体Sh1、Sh2和GBSSI表达量分别提高了1.56倍、1.45倍和1.32倍，与RNA测序结果一致。进一步研究表明ZmMYB71可能通过GATATC和TTAGGG基序直接抑制淀粉合成基因的启动子活性。此外，我们发现ZmMYB71优异单体型Hap1在高淀粉BSSS和PB类群占比超过55％，而在低淀粉PA类群中仅为7.14％。比较不同育种阶段Hap1单体型出现频率，在1980~1990年和2000年自交系中分别占28.57％和27.94％，而2010年后显著增加至40.28％。本研究为玉米籽粒淀粉的自然变异提供了宝贵信息，同时我们认为ZmMYB71作为负调控因子有潜力应用于玉米籽粒SC遗传改良。

Abstract: Starch plays a crucial role as a storage component, greatly affecting the grain yield and quality of maize (Zea mays L.).  To meet future demands, it is essential to understand the genetic basis of the natural variation in kernel starch content (SC) for maize breeding.  Through a genome-wide association study (GWAS), we identified 84 and 96 loci associated with kernel SC within two years that overlapped with 185 candidate genes.  The candidate gene ZmMYB71, which encodes a myeloblastosis (MYB)-related transcription factor, exhibited the highest co-expression frequency with starch synthesis genes.  We demonstrated that ZmMYB71 functions as a nuclear located transcription repressor, and the kernel SC of mutants increased by over 2.32%, with a minor effect on amylose content or 100-grain weight.  Sh1, Sh2, and GBSSI showed up-regulation in mutants by 1.56-, 1.45- and 1.32-fold, respectively, consistently with the RNA sequencing result; their promoter activities may be directly repressed by ZmMYB71 through the GATATC and TTAGGG motifs.  Furthermore, the ZmMYB71 elite haplotype Hap1 was present in over 55% of the high-starch maize sub-populations BSSS and PB but only in 7.14% of the low-starch sub-population PA.  Comparing the Hap1 haplotype frequencies in different breeding stages found that its frequency in the inbred group released after 2010 is significantly higher at 40.28%, in contrast to 28.57% and 27.94% in the years 1980 and 1990, and 2000, respectively.  The finding provides valuable information on the natural variation in SC of the maize kernel and suggests that ZmMYB71 serves as a negative regulator with the potential to be used to improve SC in the kernels.

Key words: maize , kernel starch content ,  , co-expression analysis ,  , ZmMYB71 ,  , negative regulator