Rhizoctonia solani Strain KM1: A Novel Virulent Strain Responsible for Sheath Blight in Rice
A novel virulent strain KM1 of Rhizoctonia solani responsible for sheath blight disease in rice was isolated from naturally infected rice from CRRI farm, Cuttack. The concerned strain was tested by artificial inoculation in rice genotype Naveen and found to be infecting 18% of sheath after seven days of inoculation and the infection progressed gradually to 28.24% after 28 days of inoculation. Further, Basic Local Alignment of Search Tool (BLAST) homology of 18S-rDNA sequence of strain KM1 confirmed the identity as Rhizoctonia solani and also showed its distictiveness from other known strains (Fig. 2). Finally, the strain was registered both in National Center for Biotechnology Information (NCBI), New York, USA and National Fungal Culture Collection of India (NFCCI), Pune, India and received the accession numbers, KJ652020 and NFCCI-3443, respectively.
U Kumar and T K Dangar
Cyanotis axillaris (L.) D. Don (Nilani phul): New Weed Host for Rice Root Knot Nematode, Meloidogyne graminicola
Rice Root Knot Nematode, Meloidogyne graminicola is one of the important pests of rice in irrigated and upland rice particularly under water stress condition. These nematodes were earlier believed to have very narrow host range within monocots. However, recent reports expanded their host range even into diocots such as Amaranthus spinosus, Ageratum conyzoides, Eclipta alba, Melilotus alba, Trigonella polyceratia, Physalis minima etc. Nematodes survive not only on rice stubbles but also on weed hosts during off season, which act as a biological bridge between two rice crops. So, a survey was conducted to identify its weed host, in which we found that Cyanotis axillaris (Syn. Amischophacelus axillaris; Ver. Nilani phul, salt-raj and baghanulla) as a new weed host of M. graminicola. This plant is a perennial herb with creeping or suberect stem; the flowers are pale blue in colour; have rooting at nodes. We confirmed this finding through Koch's postulate and re-established the same symptom. Maximum of 17 females were observed in single gall and they complete their lifecycle in approximately 28+3 days in net house studies. This weed as collateral host of RRKN can increase the menace of RRKN in rice growing areas.
S S Pokhare, Berliner J, and B C Patra