Pistillody is caused by alterations to the class-B MADS-box gene expression pattern in alloplasmic wheats
- 453 Downloads
Class-B floral homeotic genes are involved in specifying petal and stamen identity during flower development in plant species. Homeotic transformation of stamens into pistil-like structures (called pistillody) has been observed in alloplasmic lines of bread wheat (Triticum aestivum L.) having the cytoplasm of a wild relative species, Aegilops crassa Boiss. To obtain information about the molecular mechanism underlying pistillody induction, we isolated two PISTILLATA (PI)-type class-B MADS-box genes, WPI1 (wheat PI STILLATA # 1) and WPI2, from wheat. Phylogenetic reconstruction indicated that WPI1 is orthologous to OsMADS4 and that WPI2 is probably an ortholog of OsMADS2. Both OsMADS4 and OsMADS2 genes were suggested to be PI orthologs in rice, and the function of OsMADS4 as a class-B gene was proven by the transgenic study. An in situ hybridization study demonstrated that the WPI1 gene is expressed in primordia of lodicules and stamens in developing florets in wheat. In the alloplasmic wheat line exhibiting pistillody, the WPI1 transcripts were not detected in the primordia of pistil-like stamens, whereas WPI1 was expressed in the lodicules. The wheat APETALA3 (AP3)-type class-B MADS-box gene WAP3 (wheat AP3)/TaMADS#82 showed an expression pattern similar to that of WPI1. These results suggest that pistillody in alloplasmic wheats is caused by alterations to the expression pattern of class-B MADS-box genes.
KeywordsAegilops Alloplasmic line Flower development MADS-box gene Pistillody Triticum
Cytoplasmic male sterility
Expressed sequence tag
We are grateful to Dr. H.-Y. Hirano for valuable suggestions. This work was supported in part by a Grant-in-Aid for Scientific Research (B) from the Ministry of Education, Science and Culture of Japan (No. 12460006 to K.M.) and from the Fukui Prefectural Government (to K.M.).
- Chung Y-Y, Kim S-R, Kang H-G, Noh Y-S, Park MC, Finkel D, An G (1995) Characterization of two rice MADS box genes homologous to GLOBOSA. Plant Sci 109:45–56Google Scholar
- Davies B, Schwarz-Sommer Z (1994) Control of floral organ identity by homeotic MADS-box transcription factors. In: Nover L (ed) Plant promoters and transcription factors. Springer, Berlin Heidelberg New York, pp 235–258Google Scholar
- Feldman M (2001) Origin of cultivated wheat. In: Bonjean AP, Angus WJ (eds) The world wheat book. A history of wheat breeding. Lavoisier, Paris, pp 3–56Google Scholar
- Kaul MLH (1988) Male sterility in higher plants. Monographs of Theor Appl Genet, vol 10. Springer, Berlin Heidelberg New YorkGoogle Scholar
- Meguro A, Takumi S, Ogihara Y, Murai K (2003) WAG, a wheat AGAMOUS homolog, is associated with development of pistil-like stamens in alloplasmic wheats. Sex Plant Reprod 15:221–230Google Scholar
- Murai K, Tsunewaki K (1993) Photoperiod-sensitive cytoplasmic male sterility in wheat with Aegilops crassa cytoplasm. Euphytica 67:41–48Google Scholar
- Murai K, Tsunewaki K (1994) Genetic analysis on the fertility restoration by Triticum aestivum cv. Chinese Spring against photoperiod-sensitive cytoplasmic male sterility. Jpn J Genet 69:195–202Google Scholar
- Murai K, Murai R, Takumi S, Ogihara Y (1998) Cloning and characterization of cDNAs corresponding to the wheat MADS box genes. Proc 9th Int Wheat Genet Symp 1:89–94Google Scholar
- Ogihara Y, Kurihara Y, Futami K, Tsuji K, Murai K (1999) Photoperiod-sensitive cytoplasmic male sterility in wheat: nuclear-mitochondrial incompatibility results in differential processing of the mitochondrial orf25 gene. Curr Genet 36:354–362Google Scholar