Post‐infectional dynamics of leaf spot disease in Withania somnifera

Abstract

Withania somnifera is a high value medicinal plant, native to Indian sub-continent, and is extensively used in traditional systems of medicine. It is highly prone to leaf spot disease caused by Alternaria alternata, that may affect the quality of crude herbal drugs. In the present study, the accumulation of ROS (reactive oxygen species) was detected histochemically within the infected host tissue, using H 2 DCFDA (2 ′ ,7 ′ -difluorodihydrofluorescein diacetate) and DAB (3,3 ′ -diaminobenzidine) staining methods. This ROS accumulation was linked with the process of disease initiation. The microscopy studies were conducted to explore the site of pathogen invasion into the host tissue. Some changes related to tissue degeneration during the infection process have also been reported. The observed changes in the form of reducing sugar and phenolic content showed an enhancement during infestation. Carbon, nitrogen and sulphur exhibited a decreasing trend with the progression of disease. Both the net rate of photosynthesis (A) and stomatal conductance (g S ) showed a similar trend except that g S increased at the early stage of infection when the protruding fungal hyphae obstructed the stomatal closure. Further, the disintegration of chloroplasts was also observed in the infected leaves. Overall, the present study highlights a few potential targets for enhancing the disease resistance against the leaf spot pathogen of W. somnifera.

Interdependency of Reactive Oxygen Species generating and scavenging system in salt sensitive and salt tolerant cultivars of rice

“…For H 2 DCFDA assay, pieces of second leaf were incubated in 10 μM H 2 DCFDA and were vacuum infiltered for 5 min. The leaves were then washed with double distilled water and were observed under the confocal microscope using laser beam of excitation 488 nm [ 33 , 34 ].…”

Diseases of medicinal and aromatic plants, their biological impact and management

“…Further, a hyphal structure along with an increase in crystal-like substances near the aperture of stomata was also observed in diseased leaves. Similarly, post inflectional dynamics of leaf spot pathogen in W. somnifera was studied to higher level by Sharma et al (2014). Microscopic assessment using confocal microscopy of infected leaves showed the emergence of conidiophores through stomata while SEM pointed out stomata to be the site for fungal access into the host.…”

“…At the gene expression level, Tuffen (2010) reported symptoms of significantly reduced leaf size, chlorosis and increased branching along with the decrease in the expression of photosynthesis related genes in phytoplasma infected C. roseus . Sharma et al (2014) showed that leaf spot disease had significant effect on the photosynthetic efficiency of Withania , as continuous decline in carboxylation rate was observed with the progression of the disease. At the level of metabolite changes associated with pathogen infection, Choi et al (2004) observed that Phytoplasma-infected C. roseus plants showed a noticeable lightening of older leaves, which was associated with the accumulation of carbohydrates in the source leaves (Lepka et al , 1999).…”

Genetic Diversity for Root Yield and its Component Traits in Ashwagandha (Withania somnifera (L) Dunal) Pure Lines Derived from JA134 Population

“…According to World Health Organization (WHO), the international market of herbal products is around $6.2 billion, which is poised to grow to $5 trillion by the year 2050. Among the herbal plants, Ashwagandha (Withania somnifera (L.) Dunal) is an important medicinal plant widely used in various traditional systems of medicines like Ayurveda, Sidha, Unani, Homeopathy and others (Mir et al, 2012;Sharma et al, 2014). Ashwagandha is an erect, evergreen, perennial shrub belongs to the family Solanaceace.…”