Differential expression patterns of non-symbiotic hemoglobins in sugar beet (Beta vulgaris ssp. vulgaris).
Biennial sugar beet (Beta vulgaris spp. vulgaris) is a Caryophyllidae that has adapted its growth cycle to the seasonal temperature and daylength variation of temperate regions. This is the first time a holistic study of the expression pattern of non-symbiotic hemoglobins (nsHbs) is being carried out in a member of this group and under two essential environmental conditions for flowering, namely vernalization and length of photoperiod. BvHb genes were identified by sequence homology searches against the latest draft of the sugar beet genome. Three nsHb genes (BvHb1.1, BvHb1.2 and BvHb2) and one truncated Hb gene (BvHb3) were found in the genome of sugar beet. Gene expression profiling of the nsHb genes was carried out by quantitative PCR in different organs and developmental stages, as well as during vernalization and under different photoperiods. BvHb1.1 and BvHb2 showed differential expression during vernalization as well as during long and short days. The high expression of BvHb2 indicates that it has an active role in the cell, maybe even taking over some BvHb1.2 functions, except during germination where BvHb1.2 together with BvHb1.1-both Class 1 nsHbs-are highly expressed. The unprecedented finding of a leader peptide at the N-terminus of BvHb1.1, for the first time in an nsHb from higher plants, together with its observed expression indicate that it may have a very specific role due to its suggested location in chloroplasts. Our findings open up new possibilities for research, breeding and engineering since Hbs could be more involved in plant development than previously was anticipated.
Department of Pure and Applied Biochemistry, Lund University, Box 124, 221.00 Lund, Sweden.
Nélida
N
Leiva-Eriksson
Pierre A
PA
Pin
Thomas
T
Kraft
Juliane C
JC
Dohm
André E
AE
Minoche
Heinz
H
Himmelbauer
Leif
L
Bülow
D000595:Amino Acid Sequence; D027461:Beta vulgaris / Q000235:genetics* / Q000502:physiology; D035264:Flowers / Q000235:genetics / Q000502:physiology; D020869:Gene Expression Profiling; D018507:Gene Expression Regulation, Developmental; D018506:Gene Expression Regulation, Plant; D017343:Genes, Plant; D006454:Hemoglobins / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism; D008969:Molecular Sequence Data; D017440:Photoperiod; D010940:Plant Proteins / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism; D021381:Protein Transport; D016415:Sequence Alignment; D013347:Subcellular Fractions / Q000378:metabolism; D013559:Symbiosis / Q000235:genetics*
D006454:Hemoglobins; D010940:Plant Proteins
Beta vulgaris (sugar beet); carbon allocation; chloroplast transit peptide; non-symbiotic hemoglobins (nsHbs); photoperiod; vernalization