ANK6, a mitochondrial ankyrin repeat protein, is required for male-female gamete recognition in Arabidopsis thaliana.
Double fertilization in angiosperms involves several successive steps, including guidance and reception of the pollen tube and male-female gamete recognition. Each step entails extensive communication and interaction between two different reproductive cell or tissue types. Extensive research has focused on the pollen tube, namely, its interaction with the stigma and reception by maternal cells. Little is known, however, about the mechanism by which the gametes recognize each other and interact to form a zygote. We report that an ankyrin repeat protein (ANK6) is essential for fertilization, specifically for gamete recognition. ANK6 (At5g61230) was highly expressed in the male and female gametophytes before and during but not after fertilization. Genetic analysis of a T-DNA insertional mutant suggested that loss of function of ANK6 results in embryonic lethality. Moreover, male-female gamete recognition was found to be impaired only when an ank6 male gamete reached an ank6 female gamete, thereby preventing formation of homozygous zygotes. ANK6 was localized to the mitochondria, where it interacted with SIG5, a transcription initiation factor previously found to be essential for fertility. These results show that ANK6 plays a central role in male-female gamete recognition, possibly by regulating mitochondrial gene expression.
College of Life Sciences, Hunan Normal University, Changsha 410081, People's Republic of China.
Feng
F
Yu
Jia
J
Shi
Jiye
J
Zhou
Jianing
J
Gu
Qihui
Q
Chen
Jian
J
Li
Wei
W
Cheng
Dandan
D
Mao
Lianfu
L
Tian
Bob B
BB
Buchanan
Legong
L
Li
Liangbi
L
Chen
Dongping
D
Li
Sheng
S
Luan
D017089:Ankyrin Repeat; D017360:Arabidopsis / Q000235:genetics / Q000378:metabolism*; D029681:Arabidopsis Proteins / Q000235:genetics / Q000378:metabolism*; D005306:Fertilization / Q000502:physiology; D018506:Gene Expression Regulation, Plant / Q000502:physiology*; D024101:Mitochondrial Proteins / Q000235:genetics / Q000378:metabolism*; D016254:Mutagenesis, Insertional; D056771:Ovule / Q000235:genetics / Q000378:metabolism*; D053205:Pollen Tube / Q000235:genetics / Q000378:metabolism*; D012097:Repressor Proteins / Q000235:genetics / Q000378:metabolism*; D012808:Sigma Factor / Q000235:genetics / Q000378:metabolism*
C555478:ANK6 protein, Arabidopsis; D029681:Arabidopsis Proteins; D024101:Mitochondrial Proteins; D012097:Repressor Proteins; C486979:Sig5 protein, Arabidopsis; D012808:Sigma Factor