Tiwari Shalini, Gupta Sateesh Chandra, Chauhan Puneet Singh, Lata Charu
CSIR-National Botanical Research Institute, Rana Pratap Marg, Lucknow, 226001, India.
CSIR-National Institute of Science Communication and Information Resources, 14 Satsang Vihar Marg, New Delhi, 110067, India.
Plant Cell Rep. 2021 Jan;40(1):143-155. doi: 10.1007/s00299-020-02620-1. Epub 2020 Oct 21.
Overexpression of Bacillus amyloliquefaciens SN13-responsive OsNAM gene in Arabidopsis reveals its important role in beneficial plant and plant growth promoting rhizobacteria interaction by conferring stress tolerance and phytohormone modulation. Salinity is one of the major constraints that affect crop development and yield. Plants respond and adapt to salt stress via complex mechanisms that involve morpho-physiological, biochemical, and molecular changes. The expression of numerous genes is known to alter during various abiotic stresses and impart stress tolerance. Recently, some known rhizospheric microbes have also been used to mitigate the effects of abiotic stresses; however, the molecular basis of such interactions remains elusive. Therefore, the present investigation was aimed to elucidate the plant growth-promoting rhizobacteria (PGPR; Bacillus amyloliquefaciens-SN13) -induced crosstalk among salinity and phytohormones in OsNAM-overexpressed Arabidopsis plants. Transgenic plants showed increased germination percentage compared to wild-type (WT) seeds under 100 mM of NaCl. Phenotypic data showed increased root length, rosette diameter, leaf size, and biomass in transgenics than WT plants. Transgenic plants can also better maintain membrane integrity and osmolyte concentration under salinity as compared to WT. Further, gene expression analysis of AP2/ERF, GST, ERD4, and ARF2 genes showed differential expression and their positive modulation in transgenic Arabidopsis exposed to salt stress in the presence of SN13 as compared to uninoculated WT. Modulation in IAA, ABA, and GA content in inoculated plants showed the more pronounced positive effects of SN13 on transgenic plants that supported our findings on Arabidopsis-SN13 interaction. Overall, the study concludes that SN13 positively modulated expression of stress-responsive genes under salinity and alter phytohormones levels in OsNAM-overexpressed plants suggesting its extensive role in cross-talk among salinity and phytohormones in response to PGPR.
解淀粉芽孢杆菌SN13响应的OsNAM基因在拟南芥中的过表达揭示了其通过赋予胁迫耐受性和调节植物激素，在有益植物与促进植物生长的根际细菌相互作用中发挥重要作用。盐胁迫是影响作物发育和产量的主要限制因素之一。植物通过涉及形态生理、生化和分子变化的复杂机制来响应和适应盐胁迫。已知许多基因的表达在各种非生物胁迫期间会发生改变并赋予胁迫耐受性。最近，一些已知的根际微生物也被用于减轻非生物胁迫的影响；然而，这种相互作用的分子基础仍然难以捉摸。因此，本研究旨在阐明在过表达OsNAM的拟南芥植物中，促进植物生长的根际细菌（PGPR；解淀粉芽孢杆菌-SN13）诱导的盐胁迫与植物激素之间的相互作用。与野生型（WT）种子相比，转基因植物在100 mM NaCl条件下的发芽率更高。表型数据显示，转基因植物的根长、莲座直径、叶片大小和生物量均高于WT植物。与WT相比，转基因植物在盐胁迫下也能更好地维持膜完整性和渗透溶质浓度。此外，与未接种的WT相比，在存在SN13的情况下，对转基因拟南芥进行盐胁迫处理后，AP2/ERF、GST、ERD4和ARF2基因的表达分析显示出差异表达及其正向调节。接种植物中IAA、ABA和GA含量的调节表明，SN13对转基因植物具有更显著的正向作用，这支持了我们关于拟南芥-SN13相互作用的研究结果。总体而言，该研究得出结论，SN13在盐胁迫下正向调节胁迫响应基因的表达，并改变过表达OsNAM植物中的植物激素水平，表明其在响应PGPR时，在盐胁迫与植物激素之间的相互作用中发挥广泛作用。
