A Comparison of sun, ovate, fs8.1 and Auxin Application on Tomato Fruit Shape and Gene Expression

Abstract

Elongated tomato fruit shape is the result of the action of the fruit shape genes possibly in coordination with the phytohormone auxin. To investigate the possible link between auxin and the fruit shape genes, a series of auxin (2,4-D) treatments were performed on the wild-type and the fruit shape nearisogenic lines (NILs) in Solanum pimpinellifolium accession LA1589 background. Morphological and histological analyses indicated that auxin application approximately 3 weeks before anthesis led to elongated pear-shaped ovaries and fruits, which was mainly attributed to the increase of ovary/ fruit proximal end caused by the increase of both cell number and cell size. Fruit shape changes caused by SUN, OVATE and fs8.1 were primarily due to the alterations of cell number along different growth axes. Particularly, SUN caused elongation by extending cell number along the entire proximaldistal axis, whereas OVATE caused fruit elongation in the proximal area, which was most similar to the effect of auxin on ovary shape. Expression analysis of flower buds at different stages in fruit shape NILs indicated that SUN had a stronger impact on the transcriptome than OVATE and fs8.1. The sun NIL differentially expressed genes were enriched in several biological processes, such as lipid metabolism, ion transmembrane and actin cytoskeleton organization. Additionally, SUN also shifted the expression of the auxinrelated genes, including those involved in auxin biosynthesis, homeostasis, signal transduction and polar transport, indicating that SUN may regulate ovary/fruit shape through modifying the expression of auxin-related genes very early during the formation of the ovary in the developing flower.

The genome and transcriptome analysis of snake gourd provide insights into its evolution and fruit development and ripening

“…We also detected the upregulated expression of auxin-related genes. These genes may be involved in fruit elongation, as many studies have shown that phytohormones, especially auxin and gibberellins, are related to fruit growth and changes in fruit shape 55 . These results are consistent with those of previous studies that found that three homologs of auxin-related genes were differentially expressed in developing watermelon fruits 54 .…”

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

“…A mutation in the FW2.2 promoter inhibits cell division during flower development and causes a larger fruit phenotype [15]. Another gene SUN1 encodes a protein harboring an IQ67 domain and affects cell number along the entire proximal-distal axis, resulting in fruit elongation [16,17,18]. OVATE family proteins (OFPs) and TONNEAU1 Recruiting Motif proteins affect fruit shape by regulating cell division patterns during ovary development [19,20].…”

“…SUN has a stronger effect on transcriptome than OVATE and fs8.1 . Auxin has been implicated in regulating the expression of some of the fruit shape genes [18], but little is known about other molecules that may affect fruit size and shape.…”

Pepper Fruit Elongation Is Controlled by Capsicum annuum Ovate Family Protein 20

“…Auxin is involved in the regulation of cell wall loosening and cell elongation ( Majda and Robert, 2018 ; Wang et al, 2019 ). Eight genes associated with auxin signaling were differentially expressed between the bulks, mostly upregulated in the round-fruited bulk.…”