Lytic activity in pearl millet: its role in downy mildew disease resistance

Abstract

Sclerospora graminicola causes downy mildew disease in susceptible pearl millet. Molecular basis of downy mildew disease resistance has been studied. Coleoptile region has been shown earlier to be the most susceptible site for attack by the pathogen. Lytic activity is differentially expressed in the coleoptile region of 3-day-old pearl millet seedlings of resistant and susceptible cultivars. Significantly higher levels of lytic factors were measured in the coleoptile region of resistant cultivars (100%) than in that of susceptible cultivars (20%). Both constitutive and inducible lytic factors were observed in different resistant cultivars, and they were able to lyse the pathogen. The level of lytic activity correlated well with the degree of resistance as evaluated by field screening studies. The present study, therefore, proposes that lytic factors found in the coleoptile region of the pearl millet seedling, are responsible for the lysis of the pathogen in the resistant plant, and may therefore provide resistance to downy mildew disease. This study also provides a simple method to evaluate downy mildew resistance in pearl millet cultivars.