博文
杂种优势
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徐老师书中关于杂种优势的论述:
杂种优势是一个受多个因素影响的复杂生理现象。产量是作物杂种优势分析时最重要的性状。理解杂种优势的遗传基础是进行杂交预测的基础。已经提出了几种假设来解释杂种优势。在这些假说中争论的焦点是显性假说(Davenport, 1908)和超显性假说(East, 1908; Shull, 1908)。这两个假说都是基于单个遗传位点的效应来表述杂种优势。最近的研究显示互作在数量性状和杂种优势的控制中扮演了重要的角色。显性假说认为杂种优势来自于F1杂种中一个亲本的显性基因对另一个亲本的有害隐性等位基因的删除效应。这个假说强调显性对杂种优势的贡献。超显性假设认为一个位点特定的杂合等位基因组合比两个亲本中的纯合等位基因更优越。
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关于超显性假说,最近有一个单个基因的例子The flowering gene SINGLE FLOWER TRUSS drives heterosis for yield in tomato.文章摘要部分的评论:Our findings provide the first example of a single overdominant gene for yield and suggest that single heterozygous mutations may improve productivity in other agricultural organisms.
2010 SFT heterosis for yield in tomato NG.pdf
个人认为,这是关于杂种优势研究最重要的进展,这篇文章宣告对杂种优势的研究由假设水平,进入到了分子水平.
同时这个研究也为这个观点"It has been suggested that heterosis might result from the tuned activities of dosage-dependent regulatory systems controlling signaling cascades and transcriptional networks." 提供了支持证据."Our results provide a notable example of single-gene overdominance for tomato yield and offer empirical evidence that, rather than being caused by allelic interactions,subtle changes in gene dosage can lead to overdominance."简单说:杂合位点导致基因剂量的改变,产生了杂种优势.AA(两拷贝),Aa(1拷贝),aa(0拷贝).
https://wap.sciencenet.cn/blog-479743-446661.html
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