Molecular cloning and characterization of genes related to chilling tolerance in rice.

Polyadenylated RNA was isolated and a cDNA library constructed from seedlings of a chilling-tolerant rice cultivar (Oryza sativa L. subsp. Japonica cv Nipponbare). Four clones were isolated by differential screening. Northern blot hybridization using RNAs from chilling-tolerant (Nipponbare) and -sensitive (IR36) cultivars revealed higher steady-state levels of transcripts for the four genes in Nipponbare than in IR36 maintained at the same low temperatures. The accumulation of transcripts homologous to selected cDNA sequences during chilling were tissue-specific. The nucleotide and deduced amino acid sequences of three clones, pBC121, pBC442, and pBC591, were determined, and no homology was identified by comparison with the latest version of EMBL and LASL gene data bases. The deduced protein sequences from the longest open reading frame of the clones pBC121 and pBC442 are rich in leucine and serine, whereas that of the clone pBC591 contains arginine-rich basic domains.