A C2-Domain Abscisic Acid-Related Gene, IbCAR1, Positively Enhances Salt Tolerance in Sweet Potato (Ipomoea batatas (L.) Lam.)

Abstract

Plant C2-domain abscisic acid-related (CAR) protein family plays an important role in plant growth, abiotic stress responses, and defense regulation. In this study, we cloned the IbCAR1 by homologous cloning method from the transcriptomic data of Xuzishu8, which is a sweet potato cultivar with dark-purple flesh. This gene was expressed in all tissues of sweet potato, with the highest expression level in leaf tissue, and it could be induced by NaCl and ABA. Subcellular localization analyses indicated that IbCAR1 was localized in the nucleus and plasma membrane. The PI staining experiment revealed the distinctive root cell membrane integrity of overexpressed transgenic lines upon salt stress. Salt stress significantly increased the contents of proline, ABA, and the activity of superoxide dismutase (SOD), whereas the content of malondialdehyde (MDA) was decreased in overexpressed lines. On the contrary, RNA interference plants showed sensitivity to salt stress. Overexpression of IbCAR1 in sweet potatoes could improve the salt tolerance of plants, while the RNAi of IbCAR1 significantly increased sensitivity to salt stress in sweet potatoes. Meanwhile, the genes involved in ABA biosynthesis, stress response, and reactive oxygen species (ROS)-scavenging system were upregulated in overexpressed lines under salt stress. Taken together, these results demonstrated that IbCAR1 plays a positive role in salt tolerance by relying on the ABA signal transduction pathway, activating the ROS-scavenging system in sweet potatoes.

Identification and functional characterization of a flavonol synthase gene from sweet potato [Ipomoea batatas (L.) Lam.]

“…Using the pEASY-Blunt : IbFLS1 vector as a template, the coding region of IbFLS1 without a termination codon was inserted between the Sal I and Spe I sites of the pCAMBIA1301S vector (replacing GUS with GFP),using T4 DNA ligase to generate a pCAMBIA1301S-GFP : IbFLS1 fusion construct (primers are listed in Supplementary Table S1 ). The transient GFP fusion vector was infiltrated into tobacco leaves via an Agrobacterium -mediated infiltration method ( You et al., 2022 ), and the transformed leaves were monitored with a laser confocal microscope (Nikon C2).…”

“…Finally, the pCAMBIA1301S-IbFLS1-RNAi vector was successfully created by linking PBS-RNAi-FS/RS and pCAMBIA1301S (with Kpn I and Bam HI cutting sites) together. Subsequently, the IbFLS1:RNAi vector was introduced into ‘Xuzi 8’ via Agrobacterium tumefaciens -mediated transformation, as described previously ( You et al., 2022 ).…”

Role of C2-domain protein CAR1 in the plasma membrane ABA signaling response

“…Functional studies of CAR family members have been conducted in multiple species, including in rice ( Oryza sativa ), sweet potato ( Ipomoea batatas ), and Arabidopsis . CAR family members are involved in responses to salinity, wounding, blue light, and ABA, in addition to root gravitropic responses (Rodriguez et al, 2014; Dummer et al, 2016; Cheung et al, 2020; Dummer et al, 2021; You et al, 2022). In rice, GTPase activating protein 1 (OsGAP1) acts as a regulator of OsYchF1 to enhance biotic resistance (Cheung et al, 2013).…”

“…In Arabidopsis, overexpression of the rice CAR homolog Small C2 domain protein 1 (OsSMCP1) improves salt and drought tolerance (Yokotani et al, 2009). In sweet potatoes, IbCAR1 contributes to increased salt tolerance by activating the ROS scavenging system through the ABA signaling pathway (You et al, 2022). In addition to CAR1 and CAR4, CAR9 has also been reported to be involved in the ABA response in Arabidopsis .…”

Haploid-resolved and chromosome-scale genome assembly in hexa-autoploid sweetpotato (Ipomoea batatas(L.) Lam)

“…More and more genes for important traits such as resistance, quality, growth, and development of sweetpotato have been discovered. Thus far, the discovered genes have been related to the salt tolerance, drought resistance, and disease resistance of sweetpotato; they include IbP5CR, IbNFU1, IbMas, IbSIMT1, IbNHX2, IbDFR, IbMYB1, IbC3H18, IbMIPS1, IbNAC1, IbpreproHypSys, IbBBX24, IbRAP2.4, IbGATA24, IbIPUT1, IbCAR1, IbPYL8, IbbHLH66, IbbHLH118, and others [10][11][12][13][14][15][16][17][18][19][20] . The improvement of sweetpotato quality has focused mainly on starch, carotenoid, and anthocyanin.…”