Project description:Trichomes are the hair-like structures that are widely present on the surface of aerial organs and function in plant defense against biotic and abiotic stresses. Previous studies focus on the single cell trichomes in Arabidopsis and cotton, or multicellular glandular trichomes in tomato, but the developmental process and molecular mechanisms controlling multicellular non-glandular trichome development are largely neglected. Here, we extensively characterized the fruit trichome (spine) development in wild type cucumber and in a tiny branched hair (tbh) mutant that contains a spontaneous mutation and has hairless foliage and smooth fruit surface. Our data indicated that cucumber trichome was multicellular and non-glandular, with no branches or endoreduplication. Further, the major feature of cucumber trichome development was spine base expansion. Transcriptome profiling through Digital Gene Expression indicated that meristem-related genes and transcription factors were implicated in the fruit spine development, and polarity regulators were upregulated during spine base expansion. qRT-PCR verified the reliability of our RNA-SEQ data, and in situ hybridization confirmed the enriched expression of meristem regulators CUP-SHAPED COTYLEDON3 (CUC3) and STM (SHOOT MERISTEMLESS) , as well as the abaxial identity gene KANADI (KAN) in cucumber fruit spine. Together, our results suggest a distinct regulatory pathway involving meristem genes and polarity regulators in multicellular trichome development in cucumber.
