Temporal expression patterns of fruit-specific α- EXPANSINS during cell expansion in bell pepper (Capsicum annuum L.)

Abstract

Background Expansins (EXP) facilitate non-enzymatic cell wall loosening during several phases of plant growth and development including fruit growth, internode expansion, pollen tube growth, leaf and root development, and during abiotic stress responses. In this study, the spatial and temporal expression patterns of C. annuum α- EXPANSINS (CaEXPA) genes were characterized. Additionally, fruit-specific CaEXPA expression was correlated with the rate of cell expansion during bell pepper fruit development. Results Spatial expression patterns revealed that CaEXPA13 was up-regulated in vegetative tissues and flowers, with the most abundant expression in mature leaves. Expression of CaEXPA4 was associated with stems and roots. CaEXPA3 was expressed abundantly in flower at anthesis suggesting a role for CaEXPA3 in flower development. Temporal expression analysis revealed that 9 out of the 21 genes were highly expressed during fruit development. Of these, expression of six genes, CaEXPA5, CaEXPA7, CaEXPA12, CaEXPA14 CaEXPA17 and CaEXPA19 were abundant 7 to 21 days after anthesis (DAA), whereas CaEXP6 was strongly expressed between 14 and 28 DAA. Further, this study revealed that fruit growth and cell expansion occur throughout bell pepper development until ripening, with highest rates of fruit growth and cell expansion occurring between 7 and 14 DAA. The expression of CaEXPA14 and CaEXPA19 positively correlated with the rate of cell expansion, suggesting their role in post-mitotic cell expansion-mediated growth of the bell pepper fruit. In this study, a ripening specific EXP transcript, CaEXPA9 was identified, suggesting its role in cell wall disassembly during ripening.Conclusion This is the first genome-wide study of CaEXPA expression during fruit growth and development. Identification of a fruit-specific EXPAs suggest their importance in facilitating cell expansion during growth and cell wall loosening during ripening in bell pepper. These EXPA genes could be important targets for future manipulation of fruit size and ripening characteristics.

Identification of expansin genes as promoting or repressing factors for leaf elongation in tall fescue

“…The EXPA is mainly found in dicotyledons and some monocotyledons, excluding the Poaceae family, whereas EXPB predominantly exists in monocotyledonous plants (Cosgrove, 2015; Han et al, 2019). The members of the EXPA and EXPB subfamilies act on a variety of plant growth and developmental processes relating to cell wall modification, such as fruit growth (Mayorga‐Gómez & Nambeesan, 2020), root development (Muthusamy et al, 2020), leaf formation, elongation, and shape (Kuluev et al, 2014; Pien et al, 2001). Overexpressing OsEXPA8 in rice increased leaf number, flag leaf length, and width compared with the wild type (Ma et al, 2013).…”

Decrease in cell size and cell wall components under ectopic expression of the CaRLK1 gene

“…The mRNA levels of expansin genes and expansin protein levels are strongly correlated with the growth and development of root and shoot organs [10,11]. The expression of CaEXPA14 and CaEXPA19 positively correlated with the rate of cell expansion in bell pepper [12]. Expansins have been shown to bind strongly to cellulose and to allow loosening of the wall by disrupting the hydrogen bonds.…”