Centre for Crop and Environmental Sciences, Harper Adams University, Edgmond, Shropshire, TF10 8NB, UK.
Department of Plant Sciences, University of Cambridge, Downing Street, Cambridge, CB2 3EA, UK.
Plant Physiol Biochem. 2023 Aug;201:107792. doi: 10.1016/j.plaphy.2023.107792. Epub 2023 May 28.
Tipburn is a physiological disorder of lettuce (Lactuca sativa) and other leafy crops that causes external and internal leaf discolouration and results in serious quality issues for the fresh produce industry. Tipburn occurrence is difficult to predict and no completely effective control methods exist. This is compounded by poor knowledge of the underlying physiological and molecular basis of the condition, which appears to be associated with deficiency of calcium and other nutrients. Vacuolar calcium transporters, which are involved in calcium homeostasis in Arabidopsis, show differential expression in tipburn-resistant and susceptible Brassica oleracea lines. We therefore investigated expression of a subset of L. sativa vacuolar calcium transporter homologues, belonging to the Ca/H exchanger and Ca-ATPase classes, in tipburn-resistant and susceptible cultivars. This indicated that some L. sativa vacuolar calcium transporter homologues belonging to these gene classes exhibited higher expression levels in resistant cultivars, whilst others had higher expression in susceptible cultivars or were independent of tipburn phenotype. In addition, some homologues were more highly expressed in symptomatic versus asymptomatic leaves in susceptible cultivars, suggesting that tipburn-induced increases in expression are unsuccessful in conferring resistance and that differential baseline expression of such genes is important for tipburn resistance. Knowledge of individual genes associated with tipburn resistance will improve breeding for such traits and the development of resistant lettuce varieties.
顶尖失绿症是生菜（Lactuca sativa）和其他叶菜作物的一种生理失调症，会导致外部和内部叶片褪色，给新鲜农产品行业造成严重的质量问题。顶尖失绿症的发生难以预测，目前也没有完全有效的控制方法。这是由于对该病症潜在的生理和分子基础了解不足所致，而这种情况似乎与钙和其他营养物质的缺乏有关。液泡钙转运蛋白参与拟南芥的钙稳态，在抗顶尖失绿症和易感的芸薹属（Brassica oleracea）品系中表现出差异表达。因此，我们研究了属于 Ca/H 交换器和 Ca-ATP 酶类的一部分生菜液泡钙转运蛋白同源物在抗顶尖失绿症和易感品种中的表达。这表明，这些基因类别的一些生菜液泡钙转运蛋白同源物在抗品种中表现出更高的表达水平，而其他同源物在易感品种中表达水平更高，或者与顶尖失绿症表型无关。此外，在易感品种中，一些同源物在有症状的叶片中比无症状叶片中表达更高，这表明顶尖失绿症诱导的表达增加未能赋予抗性，而这些基因的差异基础表达对于顶尖失绿症抗性很重要。与顶尖失绿症抗性相关的单个基因的知识将提高此类性状的选育水平，并开发出抗顶尖失绿症的生菜品种。
