Poster: Genome evolution

Abs # 854: Molecular evolution and expression patterns of the hemoglobin family in Arabidopsis

Presenter:	Yeh, Ching-Hui , yehch63@cc.ncu.edu.tw
Authors	Yeh, Ching-Hui  (A)   Wang, Wei-Kuang  (B)   Chiang, Tzen-Yuh  (B)
Affiliations:	(A): Department of Life Sciences, National Central University (B): Department of Biology, National Cheng-Kuang University

Hemoglobin (Hb) occurs in all the kingdoms of living organisms and has been identified as oxygen-binding proteins. In vertebrates Hbs play an important role in oxygen transport in blood. However, the physiological functions of Hbs from plant sources remains unclear. There are several families of plant Hbs have been characterized. In the nodules of legumes Hbs are believed to regulate oxygen supply to nitrogen-fixing bacteria and called symbiotic Hbs. Besides, there is another plant Hb gene family called nonsymbiotic Hbs. This family of Hbs shows only limited DNA sequence similarity to the symbiotic Hbs and is not involved in nitrogen fixation. The "nonsymbiotic" Hb gene family has three members in Arabidopsis thaliana. We examined the DNA variation in three hemoglobin loci, AtHB1, AtHB2 and AtHB3 in 32 strains of Arabidopsis thaliana and 18 strains of wild relative Arabidopsis halleri. The tree topology and natural selection tests suggested that the three member of hemoglobin family in Arabidopsis might experience distinct evolutionary force. An unexpected high heterozygosity was detected in AtHB2 and AtHB3 loci of Arabidopsis halleri. The RT-PCR experiments also improved the different hemoglobin expression in leaf and root of Arabidopsis thaliana under flooding condition.