Leiva-Eriksson Nélida, Pin Pierre A, Kraft Thomas, Dohm Juliane C, Minoche André E, Himmelbauer Heinz, Bülow Leif
Department of Pure and Applied Biochemistry, Lund University, Box 124, 221.00 Lund, Sweden.
Plant Cell Physiol. 2014 Apr;55(4):834-44. doi: 10.1093/pcp/pcu027. Epub 2014 Jan 30.
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.
二年生甜菜（Beta vulgaris spp. vulgaris）是石竹目植物，其生长周期已适应温带地区的季节性温度和日照长度变化。这是首次在该植物类群的一个成员中，在开花所需的两个基本环境条件下，即春化作用和光周期长度条件下，对非共生血红蛋白（nsHbs）的表达模式进行全面研究。通过与甜菜基因组的最新草图进行序列同源性搜索，鉴定出了BvHb基因。在甜菜基因组中发现了三个nsHb基因（BvHb1.1、BvHb1.2和BvHb2）和一个截短的血红蛋白基因（BvHb3）。通过定量PCR对nsHb基因在不同器官、发育阶段以及春化作用期间和不同光周期条件下进行了基因表达谱分析。BvHb1.1和BvHb2在春化作用期间以及长日照和短日照条件下均表现出差异表达。BvHb2的高表达表明它在细胞中具有活跃作用，甚至可能承担一些BvHb1.2的功能，但在种子萌发期间除外，此时BvHb1.2与BvHb1.1（两者均为1类nsHbs）均高表达。在高等植物的nsHb中，首次在BvHb1.1的N端发现了一个前导肽，这一史无前例的发现及其观察到的表达表明，由于其推测位于叶绿体中的位置，它可能具有非常特殊的作用。我们的研究结果为研究、育种和工程开辟了新的可能性，因为血红蛋白可能比以前预期的更多地参与植物发育。
