A Factor Linking Floral Organ Identity and Growth Revealed by Characterization of the Tomato Mutant unfinished flower development (ufd)

Abstract

Floral organogenesis requires coordinated interactions between genes specifying floral organ identity and those regulating growth and size of developing floral organs. With the aim to isolate regulatory genes linking both developmental processes (i.e., floral organ identity and growth) in the tomato model species, a novel mutant altered in the formation of floral organs was further characterized. Under normal growth conditions, floral organ primordia of mutant plants were correctly initiated, however, they were unable to complete their development impeding the formation of mature and fertile flowers. Thus, the growth of floral buds was blocked at an early stage of development; therefore, we named this mutant as unfinished flower development (ufd). Genetic analysis performed in a segregating population of 543 plants showed that the abnormal phenotype was controlled by a single recessive mutation. Global gene expression analysis confirmed that several MADS-box genes regulating floral identity as well as other genes participating in cell division and different hormonal pathways were affected in their expression patterns in ufd mutant plants. Moreover, ufd mutant inflorescences showed higher hormone contents, particularly ethylene precursor 1-aminocyclopropane-1-carboxylic acid (ACC) and strigol compared to wild type. Such results indicate that UFD may have a key function as positive regulator of the development of floral primordia once they have been initiated in the four floral whorls. This function should be performed by affecting the expression of floral organ identity and growth genes, together with hormonal signaling pathways.

Ethylene Role in Plant Growth, Development and Senescence: Interaction with Other Phytohormones

“…LeHB-1 encodes a class-I HD-Zip protein that binds to the promoter of LeACO1 , involved in the regulation of tomato floral organogenesis, carpel development and ripening (Lin et al, 2008). A novel tomato mutant altered in the formation of floral organs, called unfinished flower development ( ufd ), showed higher hormone contents, particularly the ethylene precursor ACC compared to wild type (Poyatos-Pertíñez et al, 2016). Moreover, the global transcriptome profile showed that several MADS-box genes regulating floral identity as well as genes related to ethylene response were affected in ufd mutant inflorescences.…”

Temporal Distinction between Male and Female Floral Organ Development in Nicotiana tabacum cv. Xanthi (Solanaceae)

“…However, the flower bud lengths and flower organ lengths cannot be measured nondestructively in young flowers or flower primordia, which must be aged using an alternative methodology, e.g., plastochron approach [33]. The genetic mechanisms coordinating floral organ initiation and development were explored in tomato [34]. Furthermore, MADS-box genes have been identified as the key components of gene regulatory networks involved in plant responses to plant developmental plasticity under various environmental conditions [35].…”

Reflections on the ABC model of flower development

“…Early work rapidly established that regulation of ABC genes expression is a multi-layered process integrating inputs from hormonal signaling pathways with the activity of transcription factors, histone modifying enzymes, and chromatin remodeling complexes and roles for post-transcriptional mechanisms often involving mobiles noncoding RNAs and RNA processing factors (e.g. Cheng et al 2003 ; Chen 2004 ; Zhao et al 2007 ; Yamaguchi et al 2009 ; Wu et al 2012 , 2018 ; Jung et al 2014 ; Sacharowski et al 2015 ; Poyatos-Pertíñez 2016 ; Morel et al 2017 ; Lee et al 2022 ; Lin et al 2023 ). These investigations exposed a 3-step waltz regulating ABC genes: upstream factors initiate transcription across broad territories (step 1), followed by refinement (step 2), and then maintenance (step 3) of precise expression domains.…”