Scanning electron microscopy (SEM) and stomatal analysis of pomegranate (Punicaceae L.) infected with bacterial blight, Xanthomons citri pv. Punicae

Stomata act as crucial entry points for various pathogens, such as bacteria.In pomegranate, stomata help in the spread of bacterial blight disease caused by Xanthomonas citri pv.punicae (Xcp).To investigate the role of stomatal conductance in bacterial blight disease, studies were conducted on different stomatal parameters-stomatal length, width, frequency, and index.Five pomegranate varieties were screened for bacterial blight resistance under natural conditions in northwestern India.Four varieties, i.e., Mridula, Jyoti, Jodhpur Red, and Bhagwa were rated as moderately resistant in leaves and moderately susceptible in fruits, whereas Ganesh variety was rated as moderately susceptible in leaves and susceptible in fruits, based on a significant difference (HSD, p ≤ 0.05) in percent disease index.Stomatal length, width, frequency and index values were observed highest in Ganesh variety compared to varieties Mridula, Jyoti, Jodhpur Red and Bhagwa.Stomatal length and width were observed high in diseased leaves whereas stomatal frequency and index were observed high in healthy leaves.Healthy and diseased fruit peels from moderately susceptible variety Bhagwa and susceptible variety Ganesh were examined using SEM.The infected pomegranate tissues showed signs of degeneration, and Ganesh variety exhibiting a severely crushed cortex compared to Bhagwa variety.Stomatal length, width, frequency and stomatal index were positively correlated with increased in PDI.