Lignin Deposition Is Associated with Impaired Calcium and Boron Distribution in Pear Cork Spot Disorder

Cork spot disorder is a common problem affecting Asian pears. In poorly managed orchards, the incidence rate can reach up to 80%. Irregular brown spots appear on the surface of infected fruit, affecting fruit quality. However, we still do not fully understand why this disorder happens. Using ‘Cangxi Pear’ and its asymptomatic line CP6-2, we evaluated nine trees for each of the two cultivars (three biological replicates, n = 3) at six developmental stages (60–160 days after bloom). Techniques including vascular bundle staining, elemental analysis, and scanning electron microscopy were employed. The development of cork spot disorder was a dynamic process positively correlated with mature fruit weight. Lignin and cellulose accumulation was associated with vascular bundle disruption and with reduced calcium (Ca) and boron (B) transport. Deficiency of these elements—crucial for maintaining cell structure—within the fruit was associated with cork spot development. Statistical analysis used two-way ANOVA with Tukey’s HSD test (p < 0.05). This study provides new insights into the etiology of cork spot disorder in pears.