Unleashing floret fertility by a mutated homeobox gene improved grain yield during wheat evolution under domestication
Unleashing floret fertility by a mutated homeobox gene improved grain yield during wheat evolution under domestication
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通过突变同源盒基因释放小花育性，提高了驯化小麦进化过程中的谷物产量
DOI：
10.1101/434985
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发表时间：
2018
期刊：
影响因子：
--
通讯作者：
T.
中科院分区：
文献类型：
--
作者：
Sakuma;S.;Golan;G.;Guo;Z.;Ogawa;T.;Tagiri;A.;Sugimoto;K.;Bernhardt;N.;Brassac;J.;Mascher;M.;Hensel;G.;Ohnishi;S.;Jinno;H.;Yamashita;Y.;Ayalon;I.;Peleg;Z.;Schnurbusch;T.;Komatsuda;T.
小花育性是决定禾谷类作物每花序粒数的关键性状。小麦（Triticumsp.）在进化过程中，小花育性增加，目前的面包小麦（T. aestivumL.）每小穗产生三到五粒;然而，关于控制小花育性的遗传基础知之甚少。在这里，我们确定了数量性状位点谷物数量增加1（GNI 1），编码同源结构域亮氨酸拉链I类GNI 1在小麦族中通过基因复制和功能化而进化，GNI 1主要表达于最顶端的小花原基和小穗轴的部分部位，表明GNI 1抑制小穗轴的生长发育。GNI 1的表达在小麦进化过程中逐渐减少，因此，产生更多的可育小花和每小穗的谷粒。遗传分析表明，GNI 1-A的功能降低的等位基因有助于增加每小穗可育小花数。GNI 1基因敲除可提高转基因小麦的可育小花数和籽粒数。此外，携带受损等位基因的小麦植株在田间条件下增加了籽粒产量。我们的研究结果表明，基因重复和功能化产生的进化新奇性小花生育力（即减少花的数量），而对增加粮食产量的突变在小麦的进化过程中选择驯化。显着性StatementGrain数是一个基本性状的谷物产量，但其潜在的遗传基础主要是未知的小麦。在这里，我们第一次表明了小花育性增加，每穗粒数增加和田间小麦小区产量增加之间的直接联系。我们已经确定GNI 1基因编码的HD-Zip I转录因子负责增加小花育性。野生型等位基因在小穗轴发育过程中发挥抑制作用，表明该蛋白的表达主动关闭了籽粒产量潜力;而功能降低的等位基因则能产生更多的小花和籽粒。GNI 1在小麦族中通过基因复制进化，其突变在小麦和大麦驯化进化过程中受到平行的人类选择。
Floret fertility is a key trait to determine the number of grains per inflorescence in cereals. During wheat (Triticumsp.) evolution, floret fertility has been increased and current bread wheat (T. aestivumL.) produces three to five grains per spikelet; however, little is known about the genetic basis controlling floret fertility. Here we identify the quantitative trait locusGrain Number Increase 1 (GNI1), encoding a homeodomain leucine zipper class I (HD-Zip I) transcription factor.GNI1evolved in the Triticeae through gene duplication and functionalization.GNI1was predominantly expressed in the most apical floret primordia and parts of the rachilla, suggesting that GNI1 inhibits rachilla growth and development.GNI1expression decreased during wheat evolution, and as a consequence, more fertile florets and grains per spikelet are being produced. Genetic analysis revealed that the reduced-function allele ofGNI1-Acontributes to increase the number of fertile florets per spikelet. The knockdown ofGNI1in transgenic hexaploid wheat improved fertile floret and grain number. Furthermore, wheat plants carrying the impaired allele increased grain yield under field conditions. Our findings illuminate that gene duplication and functionalization generated evolutionary novelty for floret fertility (i.e. reducing floral numbers) while the mutations towards increased grain production were under selection during wheat evolution under domestication.Significance StatementGrain number is a fundamental trait for cereal grain yield; but its underlying genetic basis is mainly unknown in wheat. Here we show for the first time a direct link between increased floret fertility, higher grain number per spike and higher plot-yields of wheat in the field. We have identifiedGNI1gene encoding an HD-Zip I transcription factor responsible for increased floret fertility. The wild type allele imposes an inhibitory role specifically during rachilla development, indicating that expression of this protein actively shuts-down grain yield potential; whereas, the reduced-function allele enables more florets and grains to be produced.GNI1evolved through gene duplication in Triticeae and its mutations were under parallel human selection during wheat and barley evolution under domestication.