Sugar and Hormone Dynamics and the Expression Profiles of SUT/SUC and SWEET Sugar Transporters during Flower Development in Petunia axillaris

Abstract

Flowering is the first committed step of plant sexual reproduction. While the developing flower is a strong sink requiring large quantity of sugars from photosynthetic source tissues, this process is under-temper-spatially controlled via hormone signaling pathway and nutrient availability. Sugar transporters SUT/SUC and SWEET mediate sugars movement across membranes and play a significant role in various physiological processes, including reproductive organ development. In Petunia axillaris, a model ornamental plant, 5 SUT/SUC and 36 SWEET genes are identified in the current version of the genome. Analysis of their gene structure and chromosomal locations reveal that SWEET family is moderately expanded. Most of the transporter genes are abundantly expressed in the flower than in other organs. During the five flower developmental stages, transcript levels of PaSUT1, PaSUT3, PaSWEET13c, PaSWEET9a, PaSWEET1d, PaSWEET5a and PaSWEET14a increase with the maturation of the flower and reach their maximum in the fully open flowers. PaSWEET9c, the nectar-specific PhNEC1 orthologous, is expressed in matured and fully opened flowers. Moreover, determination of sugar concentrations and phytohormone dynamics in flowers at the five developmental stages shows that glucose is the predominant form of sugar in young flowers at the early stage but depletes at the later stage, whereas sucrose accumulates only in maturated flowers prior to the corolla opening. On the other hand, GA3 content and to a less extent IAA and zeatin decreases with the flower development; however, JA, SA and ABA display a remarkable peak at mid- or later flower developmental stage.

Plant SWEET Family of Sugar Transporters: Structure, Evolution and Biological Functions

“…Most SWEET genes of watermelon showed high expression levels in male flowers [ 73 ]. During the petunia flower development, the expression level of PaSWEET13c , - 9a , - 1d , - 5a and - 14a increases with the maturation of the flower [ 74 ]. During the anthesis, JsSWEET1 , - 2 , - 5 , - 9 , - 10 , - 16 and - 17 were highly expressed in the flowers of Jasmine ( Jasminum sambac ) [ 75 ].…”

Genome-wide analysis and characterization of Dendrocalamus farinosus SUT gene family reveal DfSUT4 involvement in sucrose transportation in plants

“…The involvement of sucrose transporters in phytohormone signaling and abiotic responses was already described in other species-for example, SlSUT2 and StSUT4 proteins were found to interact with brassinosteroid signaling, ethylene sensing, gibberellic acid responses, and auxin transport in tomato and potato (Bitterlich et al, 2014;Garg et al, 2022a). PaSUT and OsSUT1 were found to interact with hormone (auxin and cytokinin) signaling pathways to regulate the carbohydrate partitioning in Petunia axillaris flower (Rolland et al, 2002;Iftikhar et al, 2020) and the reproductive organ of rice (Zhao et al, 2022), respectively. Consistent with these conclusions, we found that DfSUT4, DfSUT5, and DfSUT6 showed significant increases in expression in response to ABA treatment within 9 h (Figure 4B).…”

“…PtaSUT4 transporters also function in photosynthesis (Frost et al, 2012) and drought response (Harding et al, 2020). Furthermore, PaSUT and OsSUT1 transporters are associated with phytohormone (auxin and cytokinin) signaling pathways in the translocation of sucrose in Petunia axillaris flower (Rolland et al, 2002;Iftikhar et al, 2020) and rice seeds (Zhao et al, 2022), respectively. More importantly, PttSUT3 transporters are responsible for carbon delivery and formation of wood fibers in a hybrid aspen (Mahboubi et al, 2013).…”

An Updated Review on the Modulation of Carbon Partitioning and Allocation in Arbuscular Mycorrhizal Plants

“…SWEET transporters function as Suc exporters, releasing Suc to the apoplast, and their function is essential for phloem loading [89]. Several events of plant development such as the embryonic and reproductive tissue development in A. thaliana, Glycine max, and Petunia axillaris have been related to the carbohydrate transport activity of SWEET proteins [90][91][92].…”