ABSTRACT Present findings hypothesize that salt-tolerant and -sensitive oilseed plants are expected to exhibit deviant patterns of growth through lipolytic events in seedling cotyledons. It reports the growth response and different lipolytic mechanisms operating during oil body (OB) mobilization in the seedling cotyledons of salt-tolerant (DRSH 1) and salt-sensitive (PSH 1962) varieties of sunflower (Helianthus annuus L.). Salt tolerance or sensitivity to 120 mM NaCl correlates with high proteolytic degradation of OB membrane proteins, particularly oleosins, whereas salt-sensitive seedling cotyledons exhibit negligible proteolytic activity, thereby retaining OB membrane integrity for a longer time. High lipoxygenase (LOX) activity and its further upregulation by salt stress are the unique features of salt-sensitive sunflower seedlings. Salt-tolerant seedling cotyledons exhibit noteworthy modulation of phospholipase-D (PLD) activity by salt stress. Salt-sensitive seedling cotyledons exhibit higher lipase activity than salt-sensitive ones and enzyme activity is downregulated by salt stress. Salt-sensitive variety exhibits higher lipid accumulation and faster lipid mobilization with seedling development than salt-tolerant variety. Accumulation of oleic and linoleic acid in the seedling cotyledons of salt-tolerant and sensitive varieties exhibits differential sensitivity to salt stress. Novel detection of hexanoic acid (6:0) is a noteworthy feature as a response to salt stress in salt-sensitive variety. These findings, thus, provide new information on long-distance salt stress sensing mechanisms at seedling stage of plant development.

中文翻译：

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耐盐和敏感的幼苗在响应盐胁迫的脂肪分解事件中表现出显着差异

摘要 目前的研究结果假设，耐盐和敏感的油籽植物预计会通过幼苗子叶中的脂解事件表现出异常的生长模式。它报告了耐盐 (DRSH 1) 和盐敏感 (PSH 1962) 向日葵品种 (Helianthus annuus L.) 幼苗子叶油体 (OB) 动员期间的生长反应和不同的脂解机制。对 120 mM NaCl 的盐耐受性或敏感性与 OB 膜蛋白（尤其是油质蛋白）的高蛋白水解降解相关，而对盐敏感的幼苗子叶的蛋白水解活性可忽略不计，从而可以更长时间地保持 OB 膜的完整性。高脂氧合酶 (LOX) 活性及其在盐胁迫下的进一步上调是盐敏感性向日葵幼苗的独特特征。耐盐幼苗子叶通过盐胁迫表现出显着的磷脂酶-D (PLD) 活性调节。盐敏感性幼苗子叶比盐敏感性幼苗表现出更高的脂肪酶活性，并且酶活性受盐胁迫下调。与耐盐品种相比，盐敏品种在幼苗发育过程中表现出更高的脂质积累和更快的脂质动员。耐盐和敏感品种的幼苗子叶中油酸和亚油酸的积累对盐胁迫表现出不同的敏感性。新检测己酸 (6:0) 是盐敏感品种对盐胁迫的响应的一个值得注意的特征。因此，这些发现为植物发育幼苗期长距离盐胁迫传感机制提供了新信息。