AUTHOR=Zhao Yan , Zhang Yongzhong , Wang Lijing , Wang Xueran , Xu Wei , Gao Xianyu , Liu Baoshen 

TITLE=Mapping and Functional Analysis of a Maize Silkless Mutant sk-A7110

JOURNAL=Frontiers in Plant Science

VOLUME=9

YEAR=2018

URL=https://www.frontiersin.org/journals/plant-science/articles/10.3389/fpls.2018.01227

DOI=10.3389/fpls.2018.01227

ISSN=1664-462X

ABSTRACT=<p>The maize (<italic>Zea mays</italic>) stigma, which is commonly known as silk, is indispensable for reproduction and thus for grain yield. Here, we isolated a spontaneous mutant <italic>sk-A7110</italic>, which completely lacks silk; scanning electron microscopy showed that the <italic>sk-A7110</italic> pistils degenerated during late floret differentiation. Genetic analysis confirmed that this trait was controlled by a recessive nuclear gene and <italic>sk-A7110</italic> was mapped to a 74.13-kb region on chromosome 2 between the simple sequence repeat markers <italic>LA714</italic> and <italic>L277</italic>. Sequence analysis of candidate genes in this interval identified a single-nucleotide insertion at position 569 downstream of the transcriptional start site in <italic>Zm00001d002970</italic>, which encodes a UDP-glycosyltransferase; this insertion produces a frameshift and premature translational termination. RNA-sequencing analysis of young ears identified 258 differentially expressed genes (DEGs) between <italic>sk-A7110</italic> and the wild type (WT), including 119 up- and 139 down-regulated genes. Interestingly, most DEGs related to jasmonic acid (JA) synthesis were up-regulated in the mutant compared to WT. Consistent with this, the JA and JA-Isoleucine (JA-Ile) contents were significantly higher in <italic>sk-A7110</italic> ears than in WT. At the same time, RNA-sequencing analysis of tassels showed that <italic>sk-A7110</italic> could reduce the number of tassel branches in maize by down-regulating the expression of <italic>UB2</italic> and <italic>UB3</italic> genes. Our identification of the <italic>sk-A7110</italic> mutant and the responsible gene will facilitate further studies on female infertility research or maize breeding.</p>