Key Laboratory of Sugarcane Biology and Genetic Breeding, Ministry of Agriculture and Rural Affairs, Fujian Agriculture and Forestry University, Fuzhou, 350002, Fujian, China.
Key Laboratory of Pathogenic Fungi and Mycotoxins of Fujian Province (Fujian Agriculture and Forestry University), Fuzhou, 350002, Fujian, China.
BMC Plant Biol. 2021 Dec 13;21(1):589. doi: 10.1186/s12870-021-03369-9.
Plasma membrane intrinsic proteins (PIPs) are plant channel proteins involved in water deficit and salinity tolerance. PIPs play a major role in plant cell water balance and responses to salt stress. Although sugarcane is prone to high salt stress, there is no report on PIPs in sugarcane.
In the present study, eight PIP family genes, termed ScPIP1-1, ScPIP1-2, ScPIP1-3, ScPIP1-4, ScPIP2-1, ScPIP2-2, ScPIP2-4 and ScPIP2-5, were obtained based on the sugarcane transcriptome database. Then, ScPIP2-1 in sugarcane was cloned and characterized. Confocal microscopy observation indicated that ScPIP2-1 was located in the plasma membrane and cytoplasm. A yeast two-hybridization experiment revealed that ScPIP2-1 does not have transcriptional activity. Real time quantitative PCR (RT-qPCR) analysis showed that ScPIP2-1 was mainly expressed in the leaf, root and bud, and its expression levels in both below- and aboveground tissues of ROC22 were up-regulated by abscisic acid (ABA), polyethylene glycol (PEG) 6000 and sodium chloride (NaCl) stresses. The chlorophyll content and ion leakage measurement suggested that ScPIP2-1 played a significant role in salt stress resistance in Nicotiana benthamiana through the transient expression test. Overexpression of ScPIP2-1 in Arabidopsis thaliana proved that this gene enhanced the salt tolerance of transgenic plants at the phenotypic (healthier state, more stable relative water content and longer root length), physiologic (more stable ion leakage, lower malondialdehyde content, higher proline content and superoxide dismutase activity) and molecular levels (higher expression levels of AtKIN2, AtP5CS1, AtP5CS2, AtDREB2, AtRD29A, AtNHX1, AtSOS1 and AtHKT1 genes and a lower expression level of the AtTRX5 gene).
This study revealed that the ScPIP2-1-mediated osmotic stress signaling cascade played a positive role in plant response to salt stress.
质膜内在蛋白（PIPs）是参与水分亏缺和耐盐性的植物通道蛋白。PIPs 在植物细胞水分平衡和对盐胁迫的反应中起主要作用。尽管甘蔗容易受到高盐胁迫的影响，但目前尚无关于甘蔗 PIPs 的报道。
本研究基于甘蔗转录组数据库，获得了 8 个 PIP 家族基因，分别命名为 ScPIP1-1、ScPIP1-2、ScPIP1-3、ScPIP1-4、ScPIP2-1、ScPIP2-2、ScPIP2-4 和 ScPIP2-5。然后，克隆并鉴定了甘蔗中的 ScPIP2-1。共焦显微镜观察表明，ScPIP2-1 定位于质膜和细胞质中。酵母双杂交实验表明，ScPIP2-1 没有转录活性。实时定量 PCR（RT-qPCR）分析表明，ScPIP2-1 主要在叶片、根和芽中表达，在 ROC22 的地上和地下组织中，其表达水平均受脱落酸（ABA）、聚乙二醇（PEG）6000 和氯化钠（NaCl）胁迫的上调。叶绿素含量和离子渗漏测量表明，ScPIP2-1 通过瞬时表达试验在烟草原生质体中对盐胁迫有显著的抗性。ScPIP2-1 在拟南芥中的过表达证明，该基因在表型（更健康的状态、更稳定的相对含水量和更长的根长）、生理（更稳定的离子渗漏、更低的丙二醛含量、更高的脯氨酸含量和超氧化物歧化酶活性）和分子水平（AtKIN2、AtP5CS1、AtP5CS2、AtDREB2、AtRD29A、AtNHX1、AtSOS1 和 AtHKT1 基因的表达水平更高，AtTRX5 基因的表达水平更低）上增强了转基因植物的耐盐性。
本研究表明，ScPIP2-1 介导的渗透胁迫信号级联在植物对盐胁迫的反应中起积极作用。
