State Key Laboratory of Rice Biology, China National Rice Research Institute, Hangzhou 310006, Zhejiang, China.
Department of Agronomy, University of Agriculture Faisalabad, Punjab 38000, Pakistan.
Int J Mol Sci. 2019 Jan 28;20(3):547. doi: 10.3390/ijms20030547.
Salt stress is one of the key abiotic stresses causing huge productivity losses in rice. In addition, the differential sensitivity to salinity of different rice genotypes during different growth stages is a major issue in mitigating salt stress in rice. Further, information on quantitative proteomics in rice addressing such an issue is scarce. In the present study, an isobaric tags for relative and absolute quantitation (iTRAQ)-based comparative protein quantification was carried out to investigate the salinity-responsive proteins and related biochemical features of two contrasting rice genotypes-Nipponbare (NPBA, ) and Liangyoupeijiu (LYP9, ), at the maximum tillering stage. The rice genotypes were exposed to four levels of salinity: 0 (control; CK), 1.5 (low salt stress; LS), 4.5 (moderate salt stress; MS), and 7.5 g of NaCl/kg dry soil (high salt stress, HS). The iTRAQ protein profiling under different salinity conditions identified a total of 5340 proteins with 1% FDR in both rice genotypes. In LYP9, comparisons of LS, MS, and HS compared with CK revealed the up-regulation of 28, 368, and 491 proteins, respectively. On the other hand, in NPBA, 239 and 337 proteins were differentially upregulated in LS and MS compared with CK, respectively. Functional characterization by KEGG and COG, along with the GO enrichment results, suggests that the differentially expressed proteins are mainly involved in regulation of salt stress responses, oxidation-reduction responses, photosynthesis, and carbohydrate metabolism. Biochemical analysis of the rice genotypes revealed that the Na⁺ and Cl uptake from soil to the leaves via the roots was increased with increasing salt stress levels in both rice genotypes. Further, increasing the salinity levels resulted in increased cell membrane injury in both rice cultivars, however more severely in NPBA. Moreover, the rice root activity was found to be higher in LYP9 roots compared with NPBA under salt stress conditions, suggesting the positive role of rice root activity in mitigating salinity. Overall, the results from the study add further insights into the differential proteome dynamics in two contrasting rice genotypes with respect to salt tolerance, and imply the candidature of LYP9 to be a greater salt tolerant genotype over NPBA.
盐胁迫是导致水稻产量大幅损失的主要非生物胁迫因素之一。此外，不同水稻基因型在不同生长阶段对盐度的敏感性差异是缓解水稻盐胁迫的一个主要问题。进一步说，关于解决这一问题的水稻定量蛋白质组学信息还很缺乏。在本研究中，我们进行了基于同位素标记相对和绝对定量（iTRAQ）的比较蛋白质定量分析，以研究两种不同水稻基因型——日本晴（NPBA， ）和两优培九（LYP9， ）在最大分蘖期对盐胁迫的响应蛋白及相关生化特征。将水稻基因型暴露于 4 个盐度水平：0（对照；CK）、1.5（低盐胁迫；LS）、4.5（中盐胁迫；MS）和 7.5 g NaCl/kg 干土（高盐胁迫，HS）。在不同盐度条件下，iTRAQ 蛋白质谱分析共鉴定到两种水稻基因型中具有 1% FDR 的 5340 种蛋白质。在 LYP9 中，与 CK 相比，LS、MS 和 HS 分别上调了 28、368 和 491 种蛋白质。另一方面，在 NPBA 中，LS 和 MS 分别比 CK 上调了 239 和 337 种蛋白质。通过 KEGG 和 COG 的功能特征分析以及 GO 富集结果表明，差异表达蛋白主要参与盐胁迫反应、氧化还原反应、光合作用和碳水化合物代谢的调节。对水稻基因型的生化分析表明，随着盐胁迫水平的增加，两种水稻基因型的根从土壤中向叶片吸收 Na⁺和 Cl⁻。此外，随着盐度水平的增加，两种水稻品种的细胞膜损伤都有所增加，但 NPBA 更为严重。此外，在盐胁迫条件下，发现 LYP9 根的水稻根活力高于 NPBA，这表明水稻根活力在缓解盐胁迫方面具有积极作用。总的来说，本研究结果进一步深入了解了两种不同水稻基因型在耐盐性方面的差异蛋白质组动态，并暗示 LYP9 比 NPBA 更具耐盐性。
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