Dynamics of Colonization and Expression of Pathogenicity Related Genes in Fusarium oxysporum f.sp. ciceri during Chickpea Vascular Wilt Disease Progression

Abstract

Fusarium wilt caused by Fusarium oxysporum f.sp. ciceri (Foc) is a constant threat to chickpea productivity in several parts of the world. Understanding the molecular basis of chickpea-Foc interaction is necessary to improve chickpea resistance to Foc and thereby the productivity of chickpea. We transformed Foc race 2 using green fluorescent protein (GFP) gene and used it to characterize pathogen progression and colonization in wilt-susceptible (JG62) and wilt-resistant (Digvijay) chickpea cultivars using confocal microscopy. We also employed quantitative PCR (qPCR) to estimate the pathogen load and progression across various tissues of both the chickpea cultivars during the course of the disease. Additionally, the expression of several candidate pathogen virulence genes was analyzed using quantitative reverse transcriptase PCR (qRT-PCR), which showed their characteristic expression in wilt-susceptible and resistant chickpea cultivars. Our results suggest that the pathogen colonizes the susceptible cultivar defeating its defense; however, albeit its entry in the resistant plant, further proliferation is severely restricted providing an evidence of efficient defense mechanism in the resistant chickpea cultivar.

Chickpea-Fusarium oxysporum interaction transcriptome reveals differential modulation of plant defense strategies

“…They were wrapped in wet sterile muslin cloth till sprouting and transferred to surface-sterilized plastic cups containing autoclaved Soil Rite (mixture of 75% Irish Peatmoss and 25% horticulture grade Expanded Perlite; obtained from M/s Naik Krushi Udyog, Pune, India). The plants were grown for one week in growth chamber (14 h light/10 h dark, 22–25 °C, 50–60% relative humidity) and inoculated with standard Foc races 1, 2 and 4 as described in our previous study 8 . Seedlings treated with sterile deionized water served as controls.…”

“…The proteomics and metabolomics approaches highlighted up-regulation of several metabolic pathways such as biosynthesis of flavonoids, isoflavonoids, phenylpropanoids, etc. in the resistant cultivar 6 – 8 .…”

Related mobile pathogenicity chromosomes in Fusarium oxysporum determine host range on cucurbits

“…In contrast to Forc016_HCT#1, Fom-derived HCT strains did not cause disease on cucumber Fo was delayed compared to colonization of susceptible plants, and only the lower hypocotyl was colonized (Zvirin et al, 2010) or only root xylem vessels were colonized (Li et al, 2014). In other studies, colonization of xylem vessels of resistant plant roots by Fo was not observed (Cohen et al, 2015;Upasani et al, 2016). In the present study, colonization of the hypocotyl of cucumber and watermelon plants by Fom005_GFP was also not observed, suggesting strong defence responses of nonhosts cucumber and watermelon at the root-stem transition.…”

“…Eventually the fungus reaches the xylem vessels of the roots and then spreads to the main root and stem in susceptible plants . In resistant plants, however, the fungus is mostly restricted to epidermal cells and the cortex (Upasani et al, 2016). Colonization patterns of compatible or incompatible interactions between Fo and its host plants has been investigated in several ff.…”

“…melonis (Zvirin et al, 2010), f. sp. ciceris (Jimenez-Fernandez et al, 2013;Upasani et al, 2016), f. sp. conglutinans (Li et al, 2014), f. sp.…”