Floral transcriptomes in woodland strawberry uncover developing receptacle and another gene networks

Authors: HOLLENDER, COURTNEY - University Of Maryland; KANG, CHUNYING - University Of Maryland; DARWISH, OMAR - Towson University; GERETZ, AVIVA - University Of Maryland; Matthews, Benjamin - Ben; Slovin, Janet; ALKHAROUF, NADIM - Towson University; LIU, ZHONGCHI - University Of Maryland

Submitted to: Plant Physiology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 5/10/2014
Publication Date: 5/30/2014
Publication URL: http://handle.nal.usda.gov/10113/61533
Citation: Hollender, C.A., Kang, C., Darwish, O., Geretz, A., Matthews, B.F., Slovin, J.P., Alkharouf, N., Liu, Z. 2014. Floral transcriptomes in woodland strawberry uncover developing receptacle and another gene networks. Plant Physiology. DOI:10.1104/pp.114.237529.

Interpretive Summary: Proper development of flowers, which contain the male and female reproductive structures, is critical for fruit development. Adverse environmental factors, such as high temperatures or drought, during specific stages of strawberry flower development decrease the length of the growing season and lead to significant decreases in fruit yield. A better understanding of which genes are active or repressed during strawberry flower development can point to ways of protecting developing flowers from environmental stresses leading to increased yields. Growers and scientists studying the molecular regulation of flower development will benefit from this research. In this paper we describe the sequences of the thousands of genes that are active in various organs of strawberry flowers throughout development. We identified a network of genes expressed in the stem tip, which underlies the female sex organs and which, after fertilization, develops into the juicy, colorful, and health promoting berry. We also discovered that many members of a specific family of genes, called F-box genes, are active at a critical stage in the development of the male reproductive structure.

Technical Abstract: Flowers are reproductive organs and precursors to fruits and seeds. While the basic tenets of the ABCE model of flower development are conserved in angiosperms, different flowering plants exhibit different and sometimes unique characteristics. A distinct feature of strawberry flowers is the development of several hundreds of individual apocarpous (unfused) carpels. These individual carpels are arranged in a spirally pattern on the subtending stem tip, the receptacle. Therefore, the receptacle is an integral part of the strawberry flower and is of significant agronomic importance, being the precursor to strawberry fruit. Taking advantage of next-generation-sequencing and Laser Capture Microdissection (LCM), we generated different tissue and stage-specific transcriptomic profiling of woodland strawberry flower development. Using pair-wise comparisons and weighted gene co-expression network analysis (WGCNA), we identified modules of co-expressed genes and hub genes of tissue-specific networks. Of particular importance is the discovery of a developing receptacle-specific module exhibiting similar molecular features to those of young floral meristems. The strawberry homologs of number of meristem regulators including LOST MERISTEM and WUSCHEL are identified as hub genes operating in the developing receptacle network. Further, almost 25% of the F-box genes in the genome are transiently induced in developing anthers at the meiosis stage, indicating active protein degradation. Together, this work provides important insights into the molecular networks underlying strawberry’s unique reproductive developmental processes. This extensive floral transcriptome dataset is publicly available and can be readily queried at the project website, serving as an important genomic resource for the plant biology research community.