D'Angeli Simone, Matteucci Maya, Fattorini Laura, Gismondi Angelo, Ludovici Matteo, Canini Antonella, Altamura Maria Maddalena
Dipartimento di Biologia Ambientale, Università 'Sapienza', P.le A. Moro 5, 00185, Rome, Italy.
Dipartimento di Biologia, Università degli Studi di Roma "Tor Vergata", Via della Ricerca Scientifica 1, 00133, Rome, Italy.
Planta. 2016 May;243(5):1279-96. doi: 10.1007/s00425-016-2490-x. Epub 2016 Feb 26.
Cold-acclimation genes in woody dicots without winter-dormancy, e.g., olive-tree, need investigation. Positive relationships between OeFAD8, OeOSM , and OeLIP19 and olive-tree cold-acclimation exist, and couple with increased lipid unsaturation and cutinisation. Olive-tree is a woody species with no winter-dormancy and low frost-tolerance. However, cold-tolerant genotypes were empirically selected, highlighting that cold-acclimation might be acquired. Proteins needed for olive-tree cold-acclimation are unknown, even if roles for osmotin (OeOSM) as leaf cryoprotectant, and seed lipid-transfer protein for endosperm cutinisation under cold, were demonstrated. In other species, FAD8, coding a desaturase producing α-linolenic acid, is activated by temperature-lowering, concomitantly with bZIP-LIP19 genes. The research was focussed on finding OeLIP19 gene(s) in olive-tree genome, and analyze it/their expression, and that of OeFAD8 and OeOSM, in drupes and leaves under different cold-conditions/developmental stages/genotypes, in comparison with changes in unsaturated lipids and cell wall cutinisation. Cold-induced cytosolic calcium transients always occurred in leaves/drupes of some genotypes, e.g., Moraiolo, but ceased in others, e.g., Canino, at specific drupe stages/cold-treatments, suggesting cold-acclimation acquisition only in the latter genotypes. Canino and Moraiolo were selected for further analyses. Cold-acclimation in Canino was confirmed by an electrolyte leakage from leaf/drupe membranes highly reduced in comparison with Moraiolo. Strong increases in fruit-epicarp/leaf-epidermis cutinisation characterized cold-acclimated Canino, and positively coupled with OeOSM expression, and immunolocalization of the coded protein. OeFAD8 expression increased with cold-acclimation, as the production of α-linolenic acid, and related compounds. An OeLIP19 gene was isolated. Its levels changed with a trend similar to OeFAD8. All together, results sustain a positive relationship between OeFAD8, OeOSM and OeLIP19 expression in olive-tree cold-acclimation. The parallel changes in unsaturated lipids and cutinisation concur to suggest orchestrated roles of the coded proteins in the process.
对没有冬季休眠的木本双子叶植物（如橄榄树）中的冷驯化基因需要进行研究。OeFAD8、OeOSM和OeLIP19与橄榄树的冷驯化之间存在正相关关系，并伴随着脂质不饱和度增加和角质化。橄榄树是一种没有冬季休眠且抗冻性低的木本植物。然而，通过经验选择出了耐寒基因型，这突出表明冷驯化可能是可以获得的。橄榄树冷驯化所需的蛋白质尚不清楚，尽管已证明渗透素（OeOSM）作为叶片防冻剂以及种子脂质转移蛋白在低温下对胚乳角质化的作用。在其他物种中，编码产生α-亚麻酸的去饱和酶的FAD8会随着温度降低而被激活，同时bZIP-LIP19基因也会被激活。该研究的重点是在橄榄树基因组中找到OeLIP19基因，并分析其在不同冷条件/发育阶段/基因型下的橄榄核和叶片中的表达，以及OeFAD8和OeOSM的表达，同时与不饱和脂质和细胞壁角质化的变化进行比较。冷诱导的细胞质钙瞬变总是发生在某些基因型（如莫拉约洛）的叶片/橄榄核中，但在其他基因型（如卡尼诺）的特定橄榄核阶段/冷处理中则停止，这表明仅在后者基因型中获得了冷驯化。选择卡尼诺和莫拉约洛进行进一步分析。与莫拉约洛相比，卡尼诺叶片/橄榄核膜的电解质渗漏显著减少，从而证实了卡尼诺的冷驯化。冷驯化的卡尼诺的果实外果皮/叶片表皮角质化显著增加，并与OeOSM表达以及编码蛋白的免疫定位呈正相关。随着冷驯化，OeFAD8的表达增加，α-亚麻酸及相关化合物的产量也增加。分离出了一个OeLIP19基因。其水平变化趋势与OeFAD8相似。总体而言，结果支持OeFAD8、OeOSM和OeLIP19在橄榄树冷驯化中的表达之间存在正相关关系。不饱和脂质和角质化的平行变化共同表明编码蛋白在该过程中发挥了协同作用。
