Table 1.
Details of experimental set up used to study Sclerotium rolfsii and chickpea interaction and summary of the observation.
| Parameter | Remarks | ||
|---|---|---|---|
| Soil moisture conditions (%) | Description | Pathogen | |
| 40 | Limiting soil moisture | Inoculated | i.S. rolfsii colonization initiation at 24 hpi. Low pathogen growth even at 48 hpi due to low soil moisture condition. ii.Physiological wilting occurred due to purely abiotic stress in plant. iii.No plant mortality. iv.Not considered for gene expression study. |
| Non-inoculated | i.Purely abiotic stress for plant ii.Considered for plant defence gene expression study w.r.t abiotic stress (48 h)† |
||
| 60 | Lower optimum soil moisture | Inoculated | i.Delayed S. rolfsii colonization initiation at 24 hpi due to lower optimum soil moisture condition and moderate disease incidence at 48 hpi. ii.Considered as combined (both biotic and abiotic) stress for plant and abiotic stress for pathogen growth. iii.Considered for gene expression studies for plant defense-related genes w.r.t combined stress and pathogenicity-causing genes w.r.t abiotic stress. |
| Non-inoculated | i.Lower optimum soil moisture condition for plant. ii.Not considered for gene expression study. |
||
| 80 | Optimum soil moisture | Inoculated | i.Early initiation of S. rolfsii colonization at 12 hpi. Progressive colonization and high disease incidence due to optimum growth condition for both chickpea and S. rolfsii. ii.Purely biotic stress for plant growth iii.Optimum condition for studying host-pathogen interaction w.r.t plant defence genes and its expression. iv.Considered for study biotic stress. |
| Non-inoculated | i.Optimum soil moisture for plant. ii.Considered as experimental control condition for plant growth. iii.Taken as control to normalize the gene expression profiles of plant defence-related genes. |
||
| 100 | Upper optimum soil moisture | Inoculated | i.Delayed S. rolfsii colonization initiation at 24 hpi due to high moisture condition, but fast growth of pathogen after the initial colonization led to disease incidence at par with optimum soil moisture condition at 48 hpi. ii.Upper optimum soil moisture for plant growth as well as pathogen growth. iii.Not considered for gene expression study. |
| Non-inoculated | i.Upper optimum soil moisture for plant growth. ii.Not considered for gene expression study. |
||
†
From the moisture stress point of view, the sampling time of 6–24 h is very short for inducing any significant abiotic stress in plants for gene expression studies, hence we have consider only 48 h sample in gene expression study w.r.t abiotic stress.