Potato Snakin-1 Gene Silencing Affects Cell Division, Primary Metabolism, and Cell Wall Composition  

Abstract

Snakin-1 (SN1) is an antimicrobial cysteine-rich peptide isolated from potato (Solanum tuberosum) that was classified as a member of the Snakin/Gibberellic Acid Stimulated in Arabidopsis protein family. In this work, a transgenic approach was used to study the role of SN1 in planta. Even when overexpressing SN1, potato lines did not show remarkable morphological differences from the wild type; SN1 silencing resulted in reduced height, which was accompanied by an overall reduction in leaf size and severe alterations of leaf shape. Analysis of the adaxial epidermis of mature leaves revealed that silenced lines had 70% to 90% increases in mean cell size with respect to wild-type leaves. Consequently, the number of epidermal cells was significantly reduced in these lines. Confocal microscopy analysis after agroinfiltration of Nicotiana benthamiana leaves showed that SN1-green fluorescent protein fusion protein was localized in plasma membrane, and bimolecular fluorescence complementation assays revealed that SN1 self-interacted in vivo. We further focused our study on leaf metabolism by applying a combination of gas chromatography coupled to mass spectrometry, Fourier transform infrared spectroscopy, and spectrophotometric techniques. These targeted analyses allowed a detailed examination of the changes occurring in 46 intermediate compounds from primary metabolic pathways and in seven cell wall constituents. We demonstrated that SN1 silencing affects cell division, leaf primary metabolism, and cell wall composition in potato plants, suggesting that SN1 has additional roles in growth and development beyond its previously assigned role in plant defense.

One new kind of phytohormonal signaling integrator: Up-and-coming GASA family genes

“…Most of the GASA proteins are located in the cell wall, suggesting their function may relate to the cell wall extension or cell division. Existing research results show that GASA protein involved in promoting 9,18,23,45 or inhibiting 27,46 cell elongation and cell division 11,19,24,32 and other developmental processes, such as flowering time regulation.…”

“…11,8,13 Wherein the variable region, the hydrophilic amino acid composition and sequence length is vary widely between family members. 10,11,13,32 Most of the GASA proteins contain only a GASA domain, except a few members comprise a PRP (proline-rich protein) structure in addition to containing GASA domain, such as PRGL in Gerbera (Gerbera hybrida) 33 and AtGASA14 in Arabidopsis. 15 Although the Snakin-2 protein of french bean (Phaseolus vulgaris) containing only a GASA domain, but this protein can form an approximately 42 kDa protein complex (FBCBP) with the Proline-rich protein PRP to play roles in plant defense.…”

“…18 In addition, studies have shown that potato Snakin-1 and Arabidopsis GASA14 are located in the plasma membrane. 15,32 GASAs response to plant hormones Growth and development of plants is often accompanied by a variety of plant hormones signal regulation. Zhang and Wang analyzed about 1200 bp promoter sequences upstream of the ATG in the 15 Arabidopsis GASA genes, respectively, using the plant cis-acting element analysis software PLACE (http://www.…”

“…39 Normally, GASA proteins form 5 or 6 disulfide bonds and these disulfide bonds may be necessary for the senior structural of GASA and be critical for the GASA protein interactions with other proteins. 12,18 GASA protein participate in the regulation of plant growth and development upon interacting with different proteins, such as rice OsGSR1 is involved in the regulation of GA and BR crosstalk through interaction with BR (brassinosteroid) synthase DIM / DWF1 protein; 14 Potato Snakin-1 protein can interact with itself to play role in in the regulating cell division of potato leaf (Nahirnak et al, 2012). 32 …”

“…14 Potato Snakin-1 protein was mainly localized on the cell membrane and can interact with itself to regulate cell division and primary metabolic processes. 32 Beech FsGASA4 stimulates the expression of salicylic acid (SA) synthetic genes and the plants SA levels to response and resistance to the abiotic stress. 43 In Arabidopsis, AtGASA5 participate in response to heat stress by regulating the SA signaling and the accumulation of heat shock protein.…”