Fruit Architecture in Polyamine-Rich Tomato Germplasm Is Determined via a Medley of Cell Cycle, Cell Expansion, and Fruit Shape Genes

Raheel Anwar; Shazia Fatima; Autar K Mattoo; Avtar K Handa

doi:10.3390/plants8100387

Fruit Architecture in Polyamine-Rich Tomato Germplasm Is Determined via a Medley of Cell Cycle, Cell Expansion, and Fruit Shape Genes

Plants (Basel). 2019 Sep 29;8(10):387. doi: 10.3390/plants8100387.

Authors

Raheel Anwar^{1

2}, Shazia Fatima³, Autar K Mattoo⁴, Avtar K Handa⁵

Affiliations

¹ Department of Horticulture and Landscape Architecture, 625 Agriculture Mall Drive, Purdue University, West Lafayette, IN 47906, USA. raheelanwar@uaf.edu.pk.
² Institute of Horticultural Sciences, University of Agriculture, Faisalabad, Punjab 38040, Pakistan. raheelanwar@uaf.edu.pk.
³ Department of Horticulture and Landscape Architecture, 625 Agriculture Mall Drive, Purdue University, West Lafayette, IN 47906, USA. shaziafatima66@gmail.com.
⁴ Sustainable Agricultural Systems Laboratory, U.S. Department of Agriculture, Agricultural Research Service, The Henry A. Wallace Beltsville Agricultural Research Center, Beltsville, MD 20705, USA. autar.mattoo@usda.gov.
⁵ Department of Horticulture and Landscape Architecture, 625 Agriculture Mall Drive, Purdue University, West Lafayette, IN 47906, USA. ahanda@purdue.edu.

Abstract

Shape and size are important features of fruits. Studies using tomatoes expressing yeast Spermidine Synthase under either a constitutive or a fruit-ripening promoter showed obovoid fruit phenotype compared to spherical fruit in controls, suggesting that polyamines (PAs) have a role in fruit shape. The obovoid fruit pericarp exhibited decreased cell layers and pericarp thickness compared to wild-type fruit. Transgenic floral buds and ovaries accumulated higher levels of free PAs, with the bound form of PAs being predominant. Transcripts of the fruit shape genes, SUN1 and OVATE, and those of CDKB2, CYCB2, KRP1 and WEE1 genes increased significantly in the transgenic ovaries 2 and 5 days after pollination (DAP). The levels of cell expansion genes CCS52A/B increased at 10 and 20 DAP in the transgenic fruits and exhibited negative correlation with free or bound forms of PAs. In addition, the cell layers and pericarp thickness of the transgenic fruits were inversely associated with free or bound PAs in 10 and 20 DAP transgenic ovaries. Collectively, these results provide evidence for a linkage between PA homeostasis and expression patterns of fruit shape, cell division, and cell expansion genes during early fruit development, and suggest role(s) of PAs in tomato fruit architecture.

Keywords: cell division; cell expansion; fruit shape; putrescine; spermidine; spermidine synthase; spermine; tomato.