Biochemical and Histopathological Changes in Chilli Pepper (Capsicum Annuum L.) in Response to Sudden Wilt Syndrome Caused by Waterlogging-Induced Hypoxia Coupled with Fusarium Oxysporum

Histological alterations in chilli pepper (Capsicum annuum L.) roots associated with sudden wilt syndrome

“…This study endeavours to gain insight into the histological and root morphometric alterations associated with sudden wilt syndrome, a relatively new and devastating disorder affecting chillies that manifests more prominently during flowering and fruiting stages resulting in rapid wilt. The primary cause, as established by this group is inundation of 24-48 h which creates hypoxic conditions in the rhizosphere leading to the rapid loss of turgidity in the leaves and collapse of the whole plant (Salaria, 2022) has established that the sudden wilt-affected chilli plants had an impaired defence system as evidenced by lower levels of total phenols, o-dihydroxyphenols, flavonoids, ascorbic acid, peroxidase, polyphenol oxidase, catalase, phenylalanine ammonia lyase, tyrosine ammonia lyase, polyphenol oxidase, lignin, relative water content, moisture stability index, moisture content in leaves, chlorophyll A and B and the gas exchange parameters (Salaria et al, 2023). Conversely, oxidative stress markers hydrogen peroxide and malondialdehyde were uplifted, along with proline, suggesting the adaptions of plants to maintain osmoregulation.…”

“…This study endeavours to gain insight into the histological and root morphometric alterations associated with sudden wilt syndrome, a relatively new and devastating disorder affecting chillies that manifests more prominently during flowering and fruiting stages resulting in rapid wilt. The primary cause, as established by this group is inundation of 24–48 h which creates hypoxic conditions in the rhizosphere leading to the rapid loss of turgidity in the leaves and collapse of the whole plant (Salaria, 2022). In affected plants, mortality is further enhanced by F. oxysporum , a fungus readily present in wilt‐sick soils.…”

“…The identification of the fungus was made by observing morphological analysis using standard reference (Leslie & Summerell, 2008;Phillips et al, 2013) and by molecular analysis using Fa (TCGTCATCGGCCACGTCGACTCT)/ Ra (CGCTACTATGTCACCGTCATTG) primers (Fusarium specific primers) (Karlsson et al, 2016). The typical symptoms including sudden leaf drooping followed by yellowing and defoliation appeared on all the test plants in flooded and inoculated pots (Salaria et al, 2023). As soon as the first symptoms of sudden wilt syndrome were evident, the root organs viz., laterals, junctions and root tips were collected from diseased and healthy plants for further assays (Figure 1).…”

“…As established by this group already, the sudden wilt in chilli occurs due to the crop inundation which creates hypoxic conditions in the rhizosphere leading to the loss of turgidity in the leaves, resulting in the sudden collapse of the plants within 2–4 days. Though not the primary cause, the presence of a soil‐borne fungus, Fusarium oxysporum can aggravate the speed of plant mortality (Salaria, 2022). Biotic or abiotic stresses alter the metabolism of the plants and there is a complex series of reactions that change the physiology, biochemistry and histology of plants.…”

“…The sudden wilt-affected plants had lower levels of total phenols, o-dihydroxyphenols, flavonoids, ascorbic acid, peroxidase, polyphenol oxidase, catalase, phenylalanine ammonia lyase, tyrosine ammonia lyase, lignin, moisture content in leaves, relative water content (RWC), membrane stability index (MSI), chlorophyll A and B and the gas exchange parameters (net photosynthesis, transpiration rate and stomatal conductance), all indicating an impaired defence system. On the contrary, there was a rise in the contents of hydrogen peroxide, malondialdehyde as well as proline, suggesting the onset of adaptive mechanisms that maintain normal osmoregulation in the stressed plants (Salaria et al, 2023). To expand understanding regarding this unexplored devastating problem, the current study was planned to determine the morphometric and histological alterations in chilli pepper roots induced by the syndrome using image analysis through root scanning, microtome-assisted optical microscopy and electron microscopy.…”