The mitochondrial gene orfH79 plays a critical role in impairing both male gametophyte development and root growth in CMS-Honglian rice.
BACKGROUND
Cytoplasmic male sterility (CMS) has often been associated with abnormal mitochondrial open reading frames. The mitochondrial gene orfH79 is a candidate gene for causing the CMS trait in CMS-Honglian (CMS-HL) rice. However, whether the orfH79 expression can actually induce CMS in rice remains unclear.


RESULTS
Western blot analysis revealed that the ORFH79 protein is mainly present in mitochondria of CMS-HL rice and is absent in the fertile line. To investigate the function of ORFH79 protein in mitochondria, this gene was fused to a mitochondrial transit peptide sequence and used to transform wild type rice, where its expression induced the gametophytic male sterile phenotype. In addition, excessive accumulation of reactive oxygen species (ROS) in the microspore, a reduced ATP/ADP ratio, decreased mitochondrial membrane potential and a lower respiration rate in the transgenic plants were found to be similar to those in CMS-HL rice. Moreover, retarded growth of primary and lateral roots accompanied by abnormal accumulation of ROS in the root tip was observed in both transgenic rice and CMS-HL rice (YTA).


CONCLUSIONS
These results suggest that the expression of orfH79 in mitochondria impairs mitochondrial function, which affects the development of both male gametophytes and the roots of CMS-HL rice.
Peng
Xiaojue
X
Key Laboratory of MOE for Plant Developmental Biology, College of Life Science, Wuhan University, Wuhan, PR China. shaoqingli@whu.edu.cn
Wang
Kun
K
Hu
Chaofeng
C
Zhu
Youlin
Y
Wang
Ting
T
Yang
Jing
J
Tong
Jiping
J
Li
Shaoqing
S
Zhu
Yingguo
Y
D000244:Adenosine Diphosphate / Q000378:metabolism; D000255:Adenosine Triphosphate / Q000378:metabolism; D020869:Gene Expression Profiling; D018506:Gene Expression Regulation, Plant; D050259:Genes, Mitochondrial / Q000502:physiology*; D053078:Membrane Potential, Mitochondrial; D008928:Mitochondria / Q000235:genetics / Q000378:metabolism; D012275:Oryza / Q000235:genetics / Q000254:growth & development / Q000378:metabolism; D018517:Plant Roots / Q000254:growth & development* / Q000378:metabolism; D030821:Plants, Genetically Modified / Q000235:genetics / Q000378:metabolism; D011058:Pollen / Q000254:growth & development* / Q000378:metabolism; D017382:Reactive Oxygen Species / Q000378:metabolism
D017382:Reactive Oxygen Species; D000244:Adenosine Diphosphate; D000255:Adenosine Triphosphate