The multiple sequence alignment was performed for putative NACHT NTPases in early green plants (green algae, bryophyte, and lycophyte) and well-known NACHT NTPases in other organisms including bacteria, archaebacteria, cyanobacteria, protozoa, fungi, and chordates and phylogenetic tree was constructed using MEGA v5.2.2. The phylogenetic analysis shows that NACHT NTPases of early green plant were grouped in a clan of NACHT NTPases of cyanobacteria or fungi (in clades III, IV, V, VI, and III). Moreover, results of delta-blast search of NACHT NTPase in C. reinhardtii revealed the the top hits with Nostoc sp PCC 7120. From phyletic patterns and delta-blast search results from the present study, we infers that the DNA for NACHT in green algae may have been transferred from the ancestors of extant cyanobacteria.