Aberrant Stamen Development is Associated with Parthenocarpic Fruit Set Through Up-Regulation of Gibberellin Biosynthesis in Tomato

Abstract

Parthenocarpy, a process in which fruit set occurs without fertilization, leads to the production of seedless fruit. A number of floral homeotic mutants with abnormal stamen development exhibit parthenocarpic fruit set. Flower development is thought to repress ovary growth before anthesis. However, the mechanism of parthenocarpic fruit development caused by aberrant flower formation is poorly understood. To investigate the molecular mechanism of parthenocarpic fruit development in floral homeotic mutants, we performed functional analysis of Tomato APETALA3 (TAP3) by loss-of-function approaches. Organ-specific promoter was used to induce organ-specific loss of function in stamen and ovary/fruit. We observed increased cell expansion in tap3 mutants and TAP3-RNAi lines during parthenocarpic fruit growth. These were predominantly accompanied by the up-regulation of GA biosynthesis genes, including SlGA20ox1, SlGA20ox2, and SlGA20ox3, as well as reduced expression of the GA-inactivating gene SlGA2ox1 and the auxin signaling gene SlARF7 involved in a crosstalk between GA and auxin. These transcriptional profiles are in agreement with the GA levels in these lines. These results suggest that stamen development negatively regulates fruit set by repressing the GA biosynthesis.

Functional Disruption of the Tomato Putative Ortholog of HAWAIIAN SKIRT Results in Facultative Parthenocarpy, Reduced Fertility and Leaf Morphological Defects

“…Fruit quality-related traits were differently affected between slhws-1 and slhws-2 and depending on the culture conditions, however, total soluble solids (°Brix) and lycopene content estimation (a*/b* ratio) were consistently higher in the mutants ( Table 4 ; Supplementary Table S6 ). Both slhws-1 and slhws-2 also showed significantly thicker pericarp, a feature commonly observed in other parthenocarpic mutants (De Jong et al, 2009; Carrera et al, 2012; Ding et al, 2013; Okabe et al, 2018).…”

“…All the plants were supplied with 1,000-fold-diluted Hyponex nutrient solution (Hyponex Japan Co., Ltd). For histological analysis, pollen viability measurement, Scanning Electron Microscope (SEM) observation and Real Time Quantitative PCR (RT-qPCR) analysis, plants were grown using 5 cm × 5 cm × 5 cm Rockwool cube (Grodan, Netherland) in a controlled-condition room as described in Okabe et al (2018) and supplied with a commercial nutrient solution (Otsuka-A nutrient solution) (OAT Agrio Co., Ltd., Osaka, Japan).…”

“…Adverse temperatures have been reported to affect negatively sexual organ development in tomato, with the male reproductive organ being most particularly sensitive to heat stress (Peet et al, 1998; Adams et al, 2001). As stamen development represses ovary development by maintaining low levels of gibberellin, a defective stamen development may induce parthenocarpy from premature gibberellin action (Medina et al, 2013; Okabe et al, 2018).…”

Loss-of-Function of a Tomato Receptor-Like Kinase Impairs Male Fertility and Induces Parthenocarpic Fruit Set

“…Indeed, the loss of function of several MADS-box genes can cause tomato parthenocarpy. For instance, the loss of function of tomato MADS-box 29 , tomato MADS-box 5 , and DEFENCIENS / TOMATO APETALA3 / STAMENLESS result in parthenocarpy, together with abnormal stamen differentiation (Pnueli et al, 1994; Ampomah-Dwamena et al, 2002; Mazzucato et al, 2008; Quinet et al, 2014; Okabe et al, 2019). Moreover, parthenocarpy was induced in tomatoes that were genetically transformed in order to inhibit stamen development at an early stage of differentiation via the expression of the BARNASE ribonuclease gene under a stamen-specific promoter (Medina et al, 2013).…”

New insights into the evolution of the SBP-box family and expression analysis of genes in the growth and development of Brassica juncea

“…Certain phytohormones can mediate various defense-related signal transduction pathways and activate the transcription of related effector genes [49]. For example, GA regulates the development of floral organs [50], whereas SA is involved in the transmission of pathogen infection signals [51]. Based on the promoter region analysis, we selected some BjuSBP genes to determine the expression levels of exogenous phytohormones.…”