Seeing red: the origin of grain pigmentation in US weedy rice.
Seeing red: the origin of grain pigmentation in US weedy rice.
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DOI：
10.1111/j.1365-294x.2010.04707.x
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发表时间：
2010-08
影响因子：
4.9
通讯作者：
Olsen KM
中科院分区：
文献类型：
--
作者：
Gross BL;Reagon M;Hsu SC;Caicedo AL;Jia Y;Olsen KM
杂草形式的作物物种在世界各地的农田中肆虐，是作物损失的主要原因，但人们对这些杂草如何进化知之甚少。红米（Oryza sativa）是美国稻田种植的一种主要杂草，因其深色的籽粒而得名。使用中性分子标记的研究表明，美国红米与驯化稻之间关系密切，这表明这种杂草可能是通过驯化稻向野生稻的逆转而产生的。我们通过检测Rc的分子变异来验证这一逆转假说，Rc是驯化稻和野生稻籽粒色素沉着差异的调控基因。Rc的功能缺失突变解释了栽培水稻中原花青素色素缺失的原因，并且主要的Rc驯化等位基因已被证明能够通过Rc位点的额外突变自发恢复到功能形式。利用156个杂草、驯化和野生稻的不同样本，我们分析了Rc及其周围4mb基因组区域的DNA序列差异。我们发现驯化等位基因的逆转并不能解释杂草的色素粒；此外，我们发现稻瘟病单倍型在栽培水稻中要么不存在，要么非常罕见。来自Rc侧翼基因组区域的序列与Rc在栽培水稻中选择性扫荡的基因组足迹一致，并且与从未在美国种植的红米与亚洲水稻的密切关系相容。
Weedy forms of crop species infest agricultural fields worldwide and are a leading cause of crop losses, yet little is known about how these weeds evolve. Red rice (Oryza sativa), a major weed of cultivated rice fields in the US, is recognized by the dark-pigmented grain that gives it its common name. Studies using neutral molecular markers have indicated a close relationship between US red rice and domesticated rice, suggesting that the weed may have originated through reversion of domesticated rice to a feral form. We have tested this reversion hypothesis by examining molecular variation at Rc, the regulatory gene responsible for grain pigmentation differences between domesticated and wild rice. Loss-of-function mutations at Rc account for the absence of proanthocyanidin pigments in cultivated rice grains, and the major rc domestication allele has been shown to be capable of spontaneous reversion to a functional form through additional mutations at the Rc locus. Using a diverse sample of 156 weedy, domesticated, and wild Oryzas, we analyzed DNA sequence variation at Rc and its surrounding 4 Mb genomic region. We find that reversion of domestication alleles does not account for the pigmented grains of weed accessions; moreover, we find that haplotypes characterizing the weed are either absent or very rare in cultivated rice. Sequences from genomic regions flanking Rc are consistent with a genomic footprint of the rc selective sweep in cultivated rice, and are compatible with a close relationship of red rice to Asian Oryzas that have never been cultivated in the US.