Transcriptomics-Based Identification of Genes Related to Tapetum Degradation and Microspore Development in Lily.

Juanjuan Sui,Yuanyuan Zhang,Yin Xin,Wenjie Jia

doi:10.3390/genes13020366

Abstract

Lily is a popular and economically ornamental crop around the world. However, its high production of pollen grains causes serious problems to consumers, including allergies and staining of clothes. During anther development, the tapetum is a crucial step for pollen formation and microspore release. Therefore, it is important to understand the mechanism of tapetum degradation and microspore development in lily where free pollen contamination occurs. Here, we used the cut lily cultivar ‘Siberia’ to characterize the process of tapetum degradation through the use of cytology and transcriptomic methods. The cytological observation indicated that, as the lily buds developed from 4 cm (Lo 4 cm) to 8 cm (Lo 8 cm), the tapetum completed the degradation process and the microspores matured. Furthermore, by comparing the transcriptome profiling among three developmental stages (Lo 4 cm, Lo 6 cm and Lo 8 cm), we identified 27 differentially expressed genes. These 27 genes were classed into 4 groups by function, namely, cell division and expansion, cell-wall morphogenesis, transcription factors, LRR-RLK (leucine-rich repeat receptor-like kinases), plant hormone biosynthesis and transduction. Quantitative real-time PCR was performed as validation of the transcriptome data. These selected genes are candidate genes for the tapetum degradation and microspore development of lily and our work provides a theoretical basis for breeding new lily cultivars without pollen.

Highlights

Is one of the most important cut flowers in the world due to its beautiful blossoms and pleasant fragrance [1,2]
The tapetal cells became long with a large nucleus and dense cytoplasm in the 3 cm buds, which is in accordance with previous results [4]
In wheat, 11 TabZIP genes have been identified to be predominantly expressed in anthers, based on whole wheat genome sequencing [53]. These results suggest that members of the NAC family and bZIP family may be involved in the process of tapetum and microspores development

Summary

Introduction

Is one of the most important cut flowers in the world due to its beautiful blossoms and pleasant fragrance [1,2]. Doubled lily varieties have no stamens and grow additional petals instead, consumers still prefer single lilies, such as popular cultivars ‘Sorbonne’ and ‘Siberia’, which still maintain their anthers and stamens [1,4]. A sterile single lily would be the ideal cultivar for consumers. A mature anther is composed of four somatic layers [5,6]. From the outside to the inside, they are the epidermis, the endothecium, the middle layer and the tapetum [5,6]

Methods

Results

Conclusion