Transcriptomic Comparison of Non-Columnar, Heterozygous Columnar and Homozygous Columnar Apple Primary Roots (Malus x domestica). Transcriptomic Apple Radicle Comparison

Primary roots (radicles) represent the first visible developmental stages of the plant and are crucial for nutrient supply and the integration of environmental signals. Here we study the transcriptomes of standard type, heterozygous and homozygous columnar primary roots of apple (Malus x domestica) obtained from seeds of openly pollinated Procats 28 apples by RNA-Seq. The columnar growth habit is characterized by a stunted main axis and the development of short fruit spurs instead of long lateral branches and possesses economic potential. Its molecular cause has been identified as a nested retrotransposon insertion; however the link between the insertion and the phenotype as well as the timing of the phenotype emergence are as yet unclear. We extend the transcriptomic studies of columnar tissues to the radicles as the earliest developmental stages and investigate whether homozygous columnar seedlings are viable.