Functional characterization of AGAMOUS-subfamily members from cotton during reproductive development and in response to plant hormones

Abstract

Expression analysis of the AG -subfamily members from G. hirsutum during flower and fruit development. Reproductive development in cotton, including the fruit and fiber formation, is a complex process; it involves the coordinated action of gene expression regulators, and it is highly influenced by plant hormones. Several studies have reported the identification and expression of the transcription factor family MADS-box members in cotton ovules and fibers; however, their roles are still elusive during the reproductive development in cotton. In this study, we evaluated the expression profiles of five MADS-box genes (GhMADS3, GhMADS4, GhMADS5, GhMADS6 and GhMADS7) belonging to the AGAMOUS-subfamily in Gossypium hirsutum. Phylogenetic and protein sequence analyses were performed using diploid (G. arboreum, G. raimondii) and tetraploid (G. barbadense, G. hirsutum) cotton genomes, as well as the AG-subfamily members from Arabidopsis thaliana, Petunia hybrida and Antirrhinum majus. qPCR analysis showed that the AG-subfamily genes had high expression during flower and fruit development in G. hirsutum. In situ hybridization analysis also substantiates the involvement of AG-subfamily members on reproductive tissues of G. hirsutum, including ovule and ovary. The effect of plant hormones on AG-subfamily genes expression was verified in cotton fruits treated with gibberellin, auxin and brassinosteroid. All the genes were significantly regulated in response to auxin, whereas only GhMADS3, GhMADS4 and GhMADS7 genes were also regulated by brassinosteroid treatment. In addition, we have investigated the GhMADS3 and GhMADS4 overexpression effects in Arabidopsis plants. Interestingly, the transgenic plants from both cotton AG-like genes in Arabidopsis significantly altered the fruit size compared to the control plants. This alteration suggests that cotton AG-like genes might act regulating fruit formation. Our results demonstrate that members of the AG-subfamily in G. hirsutum present a conserved expression profile during flower development, but also demonstrate their expression during fruit development and in response to phytohormones.

A Pivotal Role of Hormones in Regulating Cotton Fiber Development

“…GhMAPK, a member of MAPK family involved in auxin signal pathway, is predominately expressed in elongated fiber cells (Chen et al., 2001). All members of AGAMOUS subfamily were significantly induced by auxin (Moura et al., 2016). The expression levels of most GhSAUR genes are responsive to exogenous application of IAA treatment (Li et al., 2017).…”

Genetic analysis of the transition from wild to domesticated cotton (G. hirsutumL.)

“…This region of chromosome A01 also has many overlapping QTL for Fruiting habit and other Phenology traits (i.e., PHTN, TN, TNFB), which may indicate that it is a notable region for plant growth and development. The other QTL for FBFF were located solely on the DT chromosomes, and includes an AGAMOUS-like gene (Table 5) , which could act responsively to plant hormones and have function in regulating fruit formation in cotton (de Moura et al 2017). Interestingly, the QTL for FBFF on chromosome D13 overlaps with QTL for Fiber Length and therefore contains some fiberrelevant genes (Table 5), including a tubulin-related gene .…”

“…Notably, these genes all belong to the FSW QTL, which overlaps in these regions with QTL for fiber traits. An additional two candidate genes within the FSW QTL have possible roles in fruit formation: a DVL-homolog that may confer phenotypic changes in fruit and inflorescence (Wen et al 2004), and an AGAMOUS 12-like gene whose family has a suggested role in cotton fruit formation (de Moura et al 2017). The only other notable candidate gene within the Seed QTL is another AGAMOUSlike gene, which was found within the QTL for AL.…”

Overexpression of AGAMOUS-like gene PfAG5 promotes early flowering in Polypogon fugax

“…For instance, when expressed in Arabidopsis the AG-subfamily genes from Gossypium hirsutum regulate ower development and fruit formation [18]. The MIKC-type genes can be subdivided into 12 major gene clades, including oral promoters (e.g.…”