Identification of the ACA/ECA gene family and preliminary verification of their functional in calcium transport in lettuce

Calcium is one of the essential elements for plant growth, and its deficiency can easily lead to tipburn. ACA/ECA is a crucial protein involved in calcium transport in plants. In this study, we utilized bioinformatics methods to identify and analyze members of the ACA/ECA gene family in lettuce. The functions of certain ACA/ECA genes in lettuce were preliminary validated using TRV-VIGS. In this study, 18 members belonging to lettuce ACA/ECA family were identified, unveiling a certain level of conservation in their evolutionary relationships. They are unevenly distributed across eight chromosomes, with six pairs of genes displaying collinear relationships. Among these 18 members, differences exist in molecular weight, number of amino acids, theoretical isoelectric point, overall average hydrophilicity, and instability coefficient. Although there are significant variations in the number of exons, the count remains relatively consistent within the same clade of ACA/ECA genes. A total of 21 pairs of ACA/ECA genes exhibit collinearity between lettuce and Arabidopsis. The lettuce ACA/ECA gene family encompasses a diverse array of light-responsive, hormone-responsive, and anaerobic-inducible elements. The expression levels of the LsaACA2, LsaACA10, and LsaACA11 genes in the leaves of lettuce are notably high. Individually silencing these genes resulted in a decrease in calcium content in leaves and exacerbated the symptoms of tipburn. The above results establish a foundation for the further exploration of ACA/ECA gene functions in lettuce and offer a theoretical basis for mitigating the occurrence of tipburn in lettuce leaves.