Gene Expression Profiling of the Shoot Meristematic Tissues in Woodland Strawberry Fragaria vesca

Abstract

Fragaria vesca, a wild diploid strawberry, has recently emerged as a model for the cultivated strawberry and other members of the Rosaceae. Differentiation and maintenance of meristems largely determines plant architecture, flower development and ultimately fruit yield. However, in strawberry, our knowledge of molecular regulation of meristems in different developmental context is limited. In this study, we hand dissected three types of tissues than contain meristematic tissues corresponding to shoot apical meristem (SAM), flower meristem (FM), and receptacle meristem (REM), in F. vesca for RNA-seq analyses. A total of 3,009 differentially expressed genes (DEGs) were identified through pairwise comparisons. These DEGs were grouped into nine clusters with dynamic and distinct expression patterns. In these nine clusters, 336 transcription factor genes belong to 46 families were identified; some of which were significantly enriched in FM and REM such as the MADS-box family or in REM such as the B3 family. We found conserved and distinctive expression patterns of totally 149 genes whose homologs regulate flowering time or SAM, leaf, and flower development in other plant species. In addition to the ABCE genes in flower development, new MADS box genes were identified to exhibit differential expression in these different tissues. Additionally, the cytokinin and auxin pathway genes also exhibited distinct expression patterns. The Arabidopsis homeobox gene WUSCHEL (WUS), essential for stem cell maintenance, is expressed in organizing center of meristems. The F. vesca homolog FvWUS1 exhibited a broader expression domain in young strawberry flowers than its Arabidopsis counterpart. Altogether, this work provides a valuable data resource for dissecting gene regulatory networks operating in different meristematic tissues in strawberry.

The FveFT2 florigen/FveTFL1 antiflorigen balance is critical for the control of seasonal flowering in strawberry while FveFT3 modulates axillary meristem fate and yield

“…In situ hybridisation detected FveFT3 transcript accumulation in the SAM (Fig. S7a,b), which is consistent with published results from RNA‐seq analysis of terminal bud from F. vesca (Li et al ., 2019a) and F. × ananassa (Koembuoy et al ., 2020). Interestingly, FveFT3 transcripts were also detected in the AXM dome, which is consistent with a role for FveFT3 in the regulation of AXM fate (Fig.…”

Allelic Variation of MYB10 Is the Major Force Controlling Natural Variation in Skin and Flesh Color in Strawberry (Fragaria spp.) Fruit

“…Due to its simpler diploid genome, F. vesca is a model for genetic and genomic studies. Efficient genomic resources have been generated for this species, including transcriptomes (Hollender et al, 2012;Li et al, 2019) and a recently improved nearcomplete genome sequence (Shulaev et al, 2011;Edger et al, 2018). F. vesca accessions with WFs, including the sequenced Hawaii4 accession, have been described and stored in multiple germplasm repositories.…”

Time-Course Transcriptomic Profiling of Floral Induction in Cultivated Strawberry

“…Compared with the sample containing only SAM and a young leaf at 9 w, the sample at 13 w consists of SAM, a young leaf, and the flower meristem in the beginning, and the sample at 15 w consists of SAM and flower primordia ( Figure 1 A–E). Thus, investigating DEGs related to leaf development and flower development may help better understand the regulatory network of floral induction [ 18 , 52 ]. Expression patterns of 28 homologs of leaf development genes were investigated, including strawberry homologs of growth-regulating factor GRF , cell proliferation gene GRF1-INTERACTING FACTOR ( GIF1 ), adaxial-adaxial gene PHAVOLUTA ( PHV ) and some active family members, such as REGULATOR OF AXILLARY MERISTEMS 3 ( RAX3 ), KNOTTED-LIKE FROM ARABIDOPSIS THALIANA 2 ( KNAT2 ), and LATERAL ORGAN FUSION 1 ( LOF ) genes of MYB family, CUC1/2/3 of NAC family, and YAB1/5 and YAB4-like genes of YABBY family ( Figure 4 A).…”

“…Compared with the DEGs of leaf development in diploid strawberries, several conserved genes were detected, such as LATERAL SUPPRESSOR ( LAS ), CUC2/3 , FASCIATED EAR ( FEA ), etc. [ 18 ], which can serve as key genes for studying leaf development during the floral induction of strawberry.…”

“…Flowering has always been the focus of strawberry crop research. The induction of flowers generally takes three steps: the vegetative stage, in which vegetative SAM gives rise to leaf primordia; then SAM shifts to the reproductive stage, where the initiation of flower meristem occurs from SAM and the entire shoot apex looks fat; followed by the next stage, the development of flower primordia [ 17 , 18 ]. Although TERMINAL FLOWER 1 ( TFL1 ) functions to maintain the vegetative meristem in both the woodland strawberry ( Fragria vesca ) and Arabidopsis, it has been shown to be the major floral suppressor in the strawberry, whereas it plays only a minor role in flowering time in Arabidopsis [ 19 , 20 , 21 , 22 ].…”