Os04g0619300
Ctb1 is one of the quantitative trait loci (QTLs) for cold tolerance in the introgression on chromosome 4 of rice.
Contents
Annotated Information
Function
Low temperatures during the booting stage reduce rice yields by causing cold-induced male sterility[1]. Ctb1 is a QTL for cold tolerance, which is located in the introgression on chromosome 4[2]. Researches mapped Ctb1 to a 17-kb region containing two genes that encode an F-box protein and a ser/thr protein kinase. Both genes were cloned from a cold-tolerant variety, Norin-PL8, and introduced into a cold-sensitive variety, Hokkai241, and a cold-sensitive line, BT4-74-8. The cold tolerance of T2 and T3 progenies was assessed by measuring the degree of spikelet fertility in plants treated with cool water irrigation (19◦C, 25 cm) or cool air (12◦C, 4 days).
The results indicated that the F-box protein gene confers cold tolerance. Cold tolerance is associated with greater anther length, which is one of major factors in cold tolerance at the booting stage. Ctb-1 expressed cold tolerance by producing a large anther. The transgenic plants had longer anthers than non-transformed controls. The F-box protein encoded by Ctb1 interact with a subunit of the E3 ubiquitin ligase, Skp1, suggesting that an ubiquitin–proteasome pathway is involved in cold tolerance at the booting stage[1].
GO assignment(s): GO:0003674 GO:0005634 GO:0008150
Expression
Sequence analyses indicated no polymorphism between Norin-PL8 and Kirara397 in the coding regions but several polymorphisms (mostly single nucleotide polymorphisms) in the 5’ upstream regions of both F-box protein (FB) and a ser/thr protein kinase(PK). Comparing the expression of the genes in Norin-PL8 and Kirara397 by RT-PCR analysis, PK was expressed in mature leaves and young panicles. By contrast, FB was expressed preferentially in young panicles, suggesting that FB was a more likely candidate to be Ctb1. No differences were observed in expression levels between Norin-PL8 and Kirara397[1].
Evolution
K.Saito et al[2] concluded that there are at least two QTLs for cold tolerance in the introgression on chromosome 4 of rice, and tentatively designated as Ctb-1 and Ctb-2.
Knowledge Extension
Rice is a staple crop cultivated worldwide. However, since it is a cold-sensitive plant that evolved in tropical and subtropical areas, rice yields are greatly reduced under low temperature conditions. One of the factors reducing rice yields is cold-induced male sterility (CIMS). In CIMS, the growth stage that is sensitive to cold is the booting stage, especially the young microspore stage just after meiosis[3]. Low temperatures at the young microspore stage cause the degeneration of microspores and hypertrophy of tapetal cells[4].
Labs working on this gene
- Natl Agr Res Ctr Hokkaido Reg, Hitsujigaoka 1, Sapporo, Hokkaido 0628555, Japan
- Univ Florida, IFAS, Ctr Citrus Res & Educ, Lake Alfred, FL 33850 USA
- N Carolina State Univ, Dept Bot, Raleigh, NC 27695 USA
References
- ↑ 1.0 1.1 1.2 1.3 K. Saito, Y. Hayano-Saito, M. Kuroki, Y. Sato,(2010) Map-based cloning of the rice cold tolerance gene Ctb1, Plant Science, 179:97–102.
- ↑ 2.0 2.1 2.2 2.3 K. Saito, K. Miura, K. Nagano, Y. Hayano-Saito, H. Araki, A. Kato, (2001) Identification of two closely linked quantitative trait loci for cold tolerance on chromosome 4 of rice and their association with anther length, Theor. Appl. Genet. 103: 862–868.
- ↑ T. Satake, H. Hayase, (1970) Male sterility caused by cooling treatment at the young microspore stage in rice plants, V. Estimation of pollen developmental stage and the most sensitive stage to coolness, Proc. Crop Sci. Soc. Jpn. 39: 468–473.
- ↑ I. Nishiyama, (1976) Male sterility caused by cooling treatment at the young microspore stage in rice plants, XIII. Ultrastructure of tapetal hypertrophy without primary wall, Proc. Crop Sci. Soc. Jpn. 45:270–278.
