%A JIANG Cheng-Gong, SHI Hui-Min, WANG Hong-Wu, LI Kun, HUANG Chang-Ling, LIU Zhi-Fang, WU Yu-Jin, LI Shu-Qiang, HU Xiao-Jiao, MA Qing %T Phenotype analysis and gene mapping of small kernel 7 (smk7) mutant in maize %0 Journal Article %D 2021 %J Acta Agronomica Sinica %R 10.3724/SP.J.1006.2021.03015 %P 285-293 %V 47 %N 2 %U {https://zwxb.chinacrops.org/CN/abstract/article_7023.shtml} %8 2021-02-12 %X

In this study, a stable small kernel mutant, named small kernel 7 (smk7), was isolated from ethylmethane sulfonate (EMS) mutagenesis of maize inbred line B73. Compared with wild type, the smk7 mutants showed smaller kernel size, defective embryo and endosperm development and a significant decrease in 100-kernel weight. The smk7 kernels showed a low level of germination rate at 10% and cannot grow into normal plants. No significant changes were detected in protein, starch and oil content between mature wild type and smk7 kernels, but the starch grains became significantly smaller and irregular in smk7 kernels compared with wild type. The smk7 kernels could be clearly distinguished from the wild type as early as 12 days after pollination (DAP), on the basis of their smaller and emptier phenotype. Microscopic inspection of the paraffin sections revealed that the development of embryo and endosperm were delayed, and the cell wall in growth in basal endosperm transfer layers (BETL) were arrested in smk7 compared with wild type. The F2 populations with multiple backgrounds were constructed by crossing heterozygous plants (+/smk7) with several other inbred lines. Genetic analysis showed that the mutant phenotype was controlled by a single recessive gene. Based on genotyping by target sequencing (GBTS) strategy, the SMK7 was initially mapped on the short arm of chromosome 2. The fine mapping results suggested that SMK7 was located between markers RM1433917 and RM1535316, with a physical distance of 120 kb. There were eight protein-coding genes in this region. This study laid a foundation for further genes cloning and research of the SMK7 function in regulating maize kernel development.