Molecular Cloning and Characterization of Genes Related to Chilling Tolerance in Rice

Abstract

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.Rice is cultivated worldwide under diverse ecological conditions. The common environmental stress affecting growth and development of rice is the irregular exposure to low temperatures. Thus, the ability of crop plants of tropical and subtropical origins to resist a period of low temperature during growth is an agriculturally important trait. The cultivars of Indica subspecies of rice in particular are often injured by cooler temperatures (around 100C) (12). To date, the mechanism of chilling tolerance is not sufficiently understood to effectively improve resistance either by conventional or by genetic engineering techniques. Therefore, numerous plants have been studied to discover the molecular mechanism responsible for cold tolerance (for reviews, see refs. 5 and 6).In general, plants respond to low temperature exposure by inducing the synthesis of several proteins (4,8,12,14) that may lead to cold hardening and cold tolerance (5, 13). These proteins are products of a gene or genes whose expression is differentially regulated by exposure to low temperature (1,4,(6)(7)(8). Several of these cold-regulated genes have been cloned and characterized (2,9,15,21).Our previous study (12) showed that cold temperatures induced the novel synthesis of several proteins in rice seed-' L.T.B. was supported by a fellowship of the Matsumae Intemational Foundation, Japan (from April to October, 1989) and a fellowship of the Science and Technology Agency, Japan (from September 1990 to March 1991).lings of tolerant cultivars due to differential gene expression. In the present study, we focused on the molecular cloning and characterization of four cDNAs of transcripts that accumulate in seedlings of the chilling-tolerant cultivar Nipponbare at low temperatures. MATERIALS AND METHODS Plant MaterialsSeeds of two rice cultivars (Oryza sativa L. subsp. Japonica cv Nipponbare and 0. sativa L. subsp. Indica cv IR36) were dehusked and sterilized in 1% sodium hypochlorite for 15 min. After three washes with autoclaved water, the sterilized seeds were placed in a vesse...

The Arabidopsis Homolog of Yeast TAP42 and Mammalian α4 Binds to the Catalytic Subunit of Protein Phosphatase 2A and Is Induced by Chilling

“…TAP46 transcript levels could be affected by anaerobic stress, however, no such changes in mRNA levels were noted (data not shown). Our results indicate that TAP46 mRNA levels increase specifically in response to chilling stress, as is the case for its homolog in rice (Binh and Oono, 1992). Other stress treatments appear to have little effect on TAP46 mRNA levels, suggesting that the TAP46 protein might function specifically to aid plant survival during cold treatment.…”

“…The levels of Arabidopsis TAP46 mRNA increase in response to chilling stress, as is the case for its rice homolog (Binh and Oono, 1992). However, no increase in TAP46 mRNA levels was noted in seedlings subjected to heat or anaerobic stress.…”

“…1). Of these three proteins, the closest homolog to Arabidopsis TAP46 is a chilling-induced protein from rice (BC601; Binh and Oono, 1992). This protein, of unknown function, is 43% identical and 59% similar to Arabidopsis TAP46.…”

“…Alignment of the amino acid sequence of TAP46 and its homologs from various organisms. The method of Pearson and Lipman (1988) was used to align the predicted amino acid sequences of TAP46, rice chilling-induced protein (OsCIP; Binh and Oono, 1992), mammalian ␣4 (Inui et al, 1995), and S. cerevisiae TAP42 (Di Como and Arndt, 1996). Dashes indicate amino acid identity; dots represent gaps introduced to maximize amino acid alignment; asterisks indicate amino acid residues conserved in all four of the compared proteins.…”

Modulation of plant HMG-CoA reductase by protein phosphatase 2A

“…2 Cumulative evidence indicates that PP2A participates in the signaling of diverse stress conditions. 7 On the one hand, the transcript levels of particular PP2A subunits increase or decrease in response to biotic [36][37][38][39] or abiotic [39][40][41][42][43][44][45][46][47] challenges. On the other, PP2A activity or particular PP2A subunits participate as positive or negative transducers in the signaling of abscisic acid (ABA), [48][49][50] and ethylene, 51,52 in the response to cold 53 or drought, 45 or to ionic, osmotic and oxidative stress, 54 and in the defense against biotic challenge.…”