BACKGROUND AND AIMS Submergence tolerance in rice is primarily attributed to SUB1 gene action, but other associated traits such as leaf gas film (LGF) thickness, leaf hydrophobicity, porosity and leaf density have been known to aid submergence tolerance in rice. However, association of these traits with SUB1 QTL is not well worked out. In this study, we aim to investigate (i) whether the presence of SUB1 QTL in the genetic background has any influence on the thickness of the leaf gas film, and (ii) whether removal of it has any impact on stress perception and submergence tolerance in Sub1 and non-Sub1 rice? METHODS We examined twelve genotypes (including both Sub1 and non-Sub1 types) for different leaf traits like initial LGF thickness, leaf hydrophobicity tissue porosity and leaf density in order to work out the relation of these traits with SUB1 QTL in rice. Furthermore, we investigated the changes in gene expression profile and different metabolic processes in selected genotypes in the presence and absence of their LGF to study its impact on stress perception and adaptation. KEY RESULTS The initial thickness of LGF and hydrophobicity seemed to have a highly positive correlation with the presence of SUB1 QTL in the genetic background of rice; although, other leaf traits like porosity and density seemed to be independent of it. Artificial removal of LGF resulted in partial loss of tolerance showing increased ethylene production and early induction of anoxia related genes (SUB1A-1, ACS5, Ramy3D, ADH1) which manifested symptoms like increased stem elongation, faster chlorophyll and starch breakdown and partial loss of quiescence in SUB1 containing rice genotypes. Stripping of LGF resulted in early and enhanced induction of SUB1A-1 indicating quicker perception of stress. CONCLUSIONS The presence of SUB1 in the genetic background positively influences surface hydrophobicity and the concomitant LGF thickness of rice. Furthermore, LGF helps in terms of providing better ethylene ventilation and reduced in planta accumulation, owing to the slowing down of ethylene induced leaf senescence under submergence stress.

中文翻译：

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带有 SUB1 QTL 的水稻具有更大的初始叶气膜厚度，导致对淹没胁迫的感知延迟

背景和目的 水稻的耐淹性主要归因于 SUB1 基因的作用，但已知其他相关性状，如叶气膜 (LGF) 厚度、叶片疏水性、孔隙度和叶片密度，有助于水稻耐淹性。然而，这些性状与 SUB1 QTL 的关联还没有得到很好的解决。在本研究中，我们的目的是调查（i）遗传背景中SUB1 QTL的存在是否对叶气膜的厚度有任何影响，以及（ii）去除它是否对胁迫感知和淹没耐受性有任何影响在 Sub1 和非 Sub1 大米中？方法我们检查了 12 种基因型（包括 Sub1 和非 Sub1 类型）的不同叶片性状，如初始 LGF 厚度、叶片疏水性组织孔隙率和叶片密度，以确定这些性状与水稻 SUB1 QTL 的关系。此外，我们研究了在存在和不存在 LGF 的情况下选定基因型中基因表达谱和不同代谢过程的变化，以研究其对压力感知和适应的影响。主要结果 LGF 的初始厚度和疏水性似乎与水稻遗传背景中 SUB1 QTL 的存在呈高度正相关；不过，其他叶子特征，如孔隙度和密度，似乎与它无关。人工去除 LGF 导致耐受性部分丧失，显示乙烯产量增加和缺氧相关基因（SUB1A-1、ACS5、Ramy3D、ADH1）的早期诱导，表现出茎伸长增加等症状，含有 SUB1 的水稻基因型中叶绿素和淀粉分解更快，静止部分丧失。LGF 的剥离导致 SUB1A-1 的早期和增强诱导，表明对压力的感知更快。结论 遗传背景中 SUB1 的存在对水稻的表面疏水性和伴随的 LGF 厚度产生积极影响。此外，由于在淹没胁迫下乙烯诱导的叶片衰老减缓，LGF 有助于提供更好的乙烯通风并减少植物积累。结论 遗传背景中 SUB1 的存在对水稻的表面疏水性和伴随的 LGF 厚度产生积极影响。此外，由于在淹没胁迫下乙烯诱导的叶片衰老减缓，LGF 有助于提供更好的乙烯通风并减少植物积累。结论 遗传背景中 SUB1 的存在对水稻的表面疏水性和伴随的 LGF 厚度产生积极影响。此外，由于在淹没胁迫下乙烯诱导的叶片衰老减缓，LGF 有助于提供更好的乙烯通风并减少植物积累。