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

Sclerospora gramninicola causes downy mildew disease in susceptible pearl m illet. Molecular basis of downy mildew disease resistance has been studied. Coleoptile region has been shown earlier to be the most susceptible site f or attack by the pathogen. Lytic activity is differentially expressed in th e coleoptile region of 3-day-old pearl millet seedlings of resistant and su sceptible cultivars. Significantly higher levels of lytic factors were meas ured 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, t herefore, proposes that lytic factors found in the coleoptile region of the pearl millet seedling, are responsible for the lysis of the pathogen in th e resistant plant, and may therefore provide resistance to downy mildew dis ease. This study also provides a simple method to evaluate downy mildew res istance in pearl millet cultivars. (C) 2000 Elsevier Science Ireland Ltd. A ll rights reserved.