Plant Molecular Biology Laboratory, M.S. Swaminathan Research Foundation, III Cross Street, Taramani Institutional Area, Chennai 600 113, India.
Forest Molecular Entomology Laboratory, Excellent Team for Mitigation (ETM), Faculty of Forestry and Wood Sciences, Czech University of Life Sciences Prague, Prague-16500, Czech Republic.
J Exp Bot. 2022 Jan 27;73(3):998-1015. doi: 10.1093/jxb/erab440.
Oryza coarctata is the only wild rice species with significant salinity tolerance. The present work examines the role of the substantial rhizomatous tissues of O. coarctata in conferring salinity tolerance. Transition to an erect phenotype (shoot emergence) from prostrate growth of rhizome tissues is characterized by marked lignification and suberization of supporting sclerenchymatous tissue, epidermis, and bundle sheath cells in aerial shoot-proximal nodes and internodes in O. coarctata. With salinity, however, aerial shoot-proximal internodal tissues show reductions in lignification and suberization, most probably related to re-direction of carbon flux towards synthesis of the osmporotectant proline. Concurrent with hypolignification and reduced suberization, the aerial rhizomatous biomass of O. coarctata appears to have evolved mechanisms to store Na+ in these specific tissues under salinity. This was confirmed by histochemical staining, quantitative real-time reverse transcription-PCR expression patterns of genes involved in lignification/suberization, Na+ and K+ contents of internodal tissues, as well as non-invasive microelectrode ion flux measurements of NaCl-induced net Na+, K+, and H+ flux profiles of aerial nodes were determined. In O. coarctata, aerial proximal internodes appear to act as 'traffic controllers', sending required amounts of Na+ and K+ into developing leaves for osmotic adjustment and turgor-driven growth, while more deeply positioned internodes assume a Na+ buffering/storage role.
长喙野古草是唯一具有显著耐盐性的野生稻种。本研究探讨了长喙野古草大量根茎组织在赋予其耐盐性方面的作用。长喙野古草的根茎组织由匍匐生长向直立生长（芽出土）的转变，其特征是支持性厚壁组织、表皮和束鞘细胞的木质化和木栓化程度显著增加，在芽出土的近节间和节间的地上茎近端节点处尤为明显。然而，在盐胁迫下，地上茎近端节间组织的木质化和木栓化程度降低，这很可能与碳流重新定向到合成渗透保护剂脯氨酸有关。伴随着木质化和木栓化程度的降低，长喙野古草的地上根茎生物量似乎已经进化出在这些特定组织中储存 Na+的机制。这通过组织化学染色、木质化/木栓化相关基因的定量实时逆转录聚合酶链式反应表达模式、节间组织的 Na+和 K+含量以及非侵入性微电极离子通量测量得到了证实，测量了 NaCl 诱导的地上节点净 Na+、K+和 H+通量剖面的非侵入性微电极离子通量。在长喙野古草中，地上近端节间似乎充当“交通控制器”，将所需量的 Na+和 K+输送到发育中的叶片中，以进行渗透调节和膨压驱动的生长，而位置更深的节间则承担 Na+缓冲/储存的作用。
