Identification of the Key Regulatory Genes Involved in Elaborate Petal Development and Specialized Character Formation in Nigelladamascena (Ranunculaceae)

Abstract

Petals can be simple or elaborate, depending on whether they have lobes, teeth, fringes, or appendages along their margins, or possess spurs, scales, or other types of modifications on their adaxial/abaxial side, or both. Elaborate petals have been recorded in 23 orders of angiosperms and are generally believed to have played key roles in the adaptive evolution of corresponding lineages. The mechanisms underlying the formation of elaborate petals, however, are largely unclear. Here, by performing extensive transcriptomic and functional studies on Nigella damascena (Ranunculaceae), we explore the mechanisms underlying elaborate petal development and specialized character formation. In addition to the identification of genes and programs that are specifically/preferentially expressed in petals, we found genes and programs that are required for elaborate rather than simple petal development. By correlating the changes in gene expression with those in petal development, we identified 30 genes that are responsible for the marginal/ventral elaboration of petals and the initiation of several highly specialized morphological characters (e.g., pseudonectaries, long hairs, and short trichomes). Expression and functional analyses further confirmed that a class I homeodomain-leucine zipper family transcription factor gene, Nigella damascena LATE MERISTEM IDENTITY1 (NidaLMI1), plays important roles in the development of short trichomes and bifurcation of the lower lip. Our results not only provide the first portrait of elaborate petal development but also pave the way to understanding the mechanisms underlying lateral organ diversification in plants.

Overexpression of PSY1 increases fruit skin and flesh carotenoid content and reveals associated transcription factors in apple (Malus × domestica)

“…The transcriptional response to PSY1 overexpression is likely to be mediated by transcription factors, whose gene expression would be expected to correlate with their target genes, as identified using gene co-expression analysis ( Langfelder and Horvath, 2008 ; Zhang et al, 2020 ; Zogopoulos et al, 2021 ). Our analysis found six carotenoid-associated TF genes with their expression strongly correlated with fruit carotenoid accumulation during on-tree development as well as in the absence of light.…”

Genes and genome editing tools for breeding desirable phenotypes in ornamentals

“…Sequences as such, however, are not sufficient to implement genome editing approaches in plant breeding, being functional studies necessary to find out genotype-to-phenotype relationships. Recently, an extensive study performing transcriptomic and functional analyses allowed to identify a high number of candidate genes involved in the development of elaborate petals and specialized characters in N. damascena, opening the way for similar investigations in other species with complex flowers (Zhang et al 2020 ). Information derived from comparative genomics aiming to mine variation in varieties and related (sub)species, when available, could also allow the discovery of novel alleles and SNPs that can be further investigated in association studies.…”

“…Lately, 30 candidate genes responsible for the marginal/ventral development of elaborate petals and the initiation of several specialized morphological characters have been identified in the model species Nigella damascena (Ranuncolaceae). In particular, LATE MERISTEM IDENTITY1 ( NidaLMI1 ), encoding a class I homeodomain-leucine zipper family transcription factor, has been shown to play an important role in the development of trichomes and bifurcation of the lower lip (Zhang et al 2020 ).…”

Mechanisms of the Morphological Plasticity Induced by Phytohormones and the Environment in Plants

“…In a rapidly changing climate, plants are facing great challenges from the environment. Recent advances in omics technologies and gene transformation have allowed genetic analyses to investigate the molecular mechanisms of plant development, ecology, and evolution [ 3 , 170 ]. Recent works also have made great breakthroughs in the fields of environmental signals sensing [ 171 , 172 , 173 ], phytohormone interactive networks [ 29 ], and plant stress combinations [ 174 , 175 ].…”