玉米多叶矮化突变体lyd1的鉴定与基因克隆

Identification and gene cloning of leafy dwarf mutant lyd1 in maize

玉米株高降低通常是由节间数目减少、节间长度变短或二者共同作用所致。而本研究在基因编辑后代中发现的玉米多叶矮化突变体lyd1却表现为节间数目显著增加,株高显著降低。lyd1株高仅为93.10 cm,与野生型KN5585的株高159.95 cm相比,降低了41.79%,差异达到极显著水平。然而lyd1叶片数平均达到27.8片,相较野生型平均17.8片叶,增加56.18%,差异达到极显著水平。遗传分析表明,lyd1的突变表型由1对隐性核基因控制,通过图位克隆将控制多叶矮化性状的基因定位于玉米3号染色体标记Indel10和Indel11之间,物理距离0.74 Mb。对定位区间内13个基因(不包含假基因)的序列进行测序,发现仅ZmTE1在第4外显子出现1个A碱基的替换,其他基因无差异。ZmTE1编码一个RNA结合蛋白,氨基酸的替换发生在第3个RNA结合结构域内(RRM3),导致天冬氨酸转变为缬氨酸。突变体lyd1的突变位点与已报道的te1-mum1、te1-mum^(2)、te1-mum^(3)、zm66不同,lyd1的发现为进一步解析玉米叶片和节间发育平衡的遗传机制提供了宝贵的材料。

The decrease of plant height in maize is usually caused by the decrease in the number of internodes,the shortening of internodes or the combination of both.However,in this study,the mutant leafy dwarf1(lyd1)found in the progeny of gene editing,exhibited more leaves and shorter stature.Quantitative measurements indicated the plant height of mutant lyd1 was only 93.10 cm,the plant height of wild-type KN5585 was 159.95 cm.The plant height was significantly reduced by 41.79% in mutant lyd1 compared with the wild type KN5585.The wild type KN5585 produced an average of 17.8 leaves at maturity stage,whereas mutants lyd1 produced 27.8 leaves.The number of leaves were significantly increased by 56.18%in mutant lyd1 compared with the wild type.Genetic analysis showed that the mutation phenotype of lyd1 was controlled by a pair of recessive nuclear genes.We applied a map-based cloning strategy to identify the gene responsible for the lyd1 phenotype.The gene was located between Indel10 and Indel11 on maize chromosome 3,and the physical distance was 0.74 Mb.Gene sequencing analysis of 13 genes(excluding pseudogenes) with in the interval revealed that one base A was substituted in the fourth exon of ZmTE1,and there was no significant difference in other genes.ZmTE1 encoded an RNA-binding protein.The amino acid substitution was in the third RNA binding domain(RRM3),resulting in the conversion of aspartic acid to valine.The mutation sites of the mutant lyd1 were different from te1-mum1,te1-mum^(2),te1-mum^(3),and zm66 in previously reported.The discovery of lyd1 provides valuable materials for further analysis of the genetic mechanism of the balance between leaves and internodes development in maize.