A Pseudo-Response Regulator is misexpressed in the photoperiod insensitive Ppd-D1a mutant of wheat (Triticum aestivum L.)
A Pseudo-Response Regulator is misexpressed in the photoperiod insensitive Ppd-D1a mutant of wheat (Triticum aestivum L.)
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DOI：
10.1007/s00122-007-0603-4
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发表时间：
2007-09-01
影响因子：
5.4
通讯作者：
Laurie, David A.
中科院分区：
文献类型：
--
作者：
Beales, James;Turner, Adrian;Laurie, David A.
位于2D染色体上的Ppd-D1是六倍体小麦的主要光周期反应位点。在“绿色革命”中广泛使用的半显性突变将小麦从长日照（LD）转化为光周期不敏感（日中性）植物，从而提供对广泛环境的适应。比较定位结果表明，Ppd-D1与大麦Ppd-H1基因共线性，后者属于伪反应调节基因家族。为了研究小麦和大麦光周期基因之间的关系，我们从中国春小麦BAC文库中分离了Ppd-H1的同源序列，并将它们与已知Ppd等位基因的其他小麦品种的序列进行了比较。具有引起短（SD）或LD早开花的光周期不敏感Ppd-D1 a等位基因的品种在编码区上游具有2kb缺失。这与2D PRR基因的错误表达和关键花调节因子FT在SD中的表达有关，表明光周期不敏感是由于已知光周期途径的激活而与日长无关。发现5个Ppd-D1等位基因，但只有2 kb的缺失与光周期不敏感。光周期不敏感性也可以通过染色体2B上的同源染色体基因座（Ppd-B1）的突变来赋予。没有候选突变被发现在2B PRR基因，但多态性内的2B PRR基因与Ppd-B1位点的双单倍体人口共分离，这表明2B上的不敏感性是由于测序区域以外的突变或紧密连锁的基因。
Ppd-D1 on chromosome 2D is the major photoperiod response locus in hexaploid wheat (Triticum aestivum). A semi-dominant mutation widely used in the "green revolution" converts wheat from a long day (LD) to a photoperiod insensitive (day neutral) plant, providing adaptation to a broad range of environments. Comparative mapping shows Ppd-D1 to be colinear with the Ppd-H1 gene of barley (Hordeum vulgare) which is a member of the pseudo-response regulator (PRR) gene family. To investigate the relationship between wheat and barley photoperiod genes we isolated homologues of Ppd-H1 from a Chinese Spring' wheat BAC library and compared them to sequences from other wheat varieties with known Ppd alleles. Varieties with the photoperiod insensitive Ppd-D1a allele which causes early flowering in short (SD) or LDs had a 2 kb deletion upstream of the coding region. This was associated with misexpression of the 2D PRR gene and expression of the key floral regulator FT in SDs, showing that photoperiod insensitivity is due to activation of a known photoperiod pathway irrespective of day length. Five Ppd-D1 alleles were found but only the 2 kb deletion was associated with photoperiod insensitivity. Photoperiod insensitivity can also be conferred by mutation at a homoeologous locus on chromosome 2B (Ppd-B1). No candidate mutation was found in the 2B PRR gene but polymorphism within the 2B PRR gene cosegregated with the Ppd-B1 locus in a doubled haploid population, suggesting that insensitivity on 2B is due to a mutation outside the sequenced region or to a closely linked gene.