Identification and characterization of a novel stay‐green QTL that increases yield in maize
Identification and characterization of a novel stay‐green QTL that increases yield in maize
复制标题
DOI：
10.1111/pbi.13139
复制
发表时间：
2019-05
影响因子：
13.8
通讯作者：
Jun Zhang;K. Fengler;J. V. Van Hemert;Rajeev Gupta;Nick Mongar;Jindong Sun;William B. Allen;
中科院分区：
文献类型：
--
作者：
Jun Zhang;K. Fengler;J. V. Van Hemert;Rajeev Gupta;Nick Mongar;Jindong Sun;William B. Allen;
功能性持绿绿色是一种有价值的性状，它延长了光合期，增加了源容量和生物量，并最终转化为更高的谷物产量。对高产的选择增加了现代玉米杂交种的保绿色。在这里，我们报告了一个新的QTL控制功能停留-绿色，发现在来自伊利诺伊州高蛋白1（IHP 1）和伊利诺伊州低蛋白1（ILP 1）线，这显示出非常不同的叶片衰老速率的作图群体。这个QTL被定位到一个含有NAC结构域转录因子的单基因上，我们将其命名为nac 7。通过RNAi下调nac 7的转基因玉米品系显示延迟衰老并增加营养组织中的生物量和氮积累，证明NAC 7作为保持绿色性状的负调节剂起作用。更重要的是，nac 7 RNAi亲本和两种不同的优良自交系测试者之间的杂交产生了具有延长的保持绿色的杂交种，并在2年的多环境田间试验中将谷物产量平均增加了0.29兆克/公顷（4.6蒲式耳/英亩）。随后的RNAseq实验，一个使用nac 7 RNAi叶，另一个使用过表达Nac 7的叶原生质体，揭示了NAC 7在调节光合作用、叶绿素降解和蛋白质周转途径中的基因中的重要作用，每一个都有助于功能性保持绿色表型。我们进一步确定了NAC 7的假定靶标，并为NAC 7在调节营养源到生殖库组织的资源分配中的作用提供了逻辑延伸。总的来说，我们的研究结果为IAC 7作为改善玉米和其他作物功能性保绿色和产量的目标提供了令人信服的理由。
Summary Functional stay‐green is a valuable trait that extends the photosynthetic period, increases source capacity and biomass and ultimately translates to higher grain yield. Selection for higher yields has increased stay‐green in modern maize hybrids. Here, we report a novel QTL controlling functional stay‐green that was discovered in a mapping population derived from the Illinois High Protein 1 (IHP1) and Illinois Low Protein 1 (ILP1) lines, which show very different rates of leaf senescence. This QTL was mapped to a single gene containing a NAC‐domain transcription factor that we named nac7. Transgenic maize lines where nac7 was down‐regulated by RNAi showed delayed senescence and increased both biomass and nitrogen accumulation in vegetative tissues, demonstrating NAC7 functions as a negative regulator of the stay‐green trait. More importantly, crosses between nac7 RNAi parents and two different elite inbred testers produced hybrids with prolonged stay‐green and increased grain yield by an average 0.29 megagram/hectare (4.6 bushel/acre), in 2 years of multi‐environment field trials. Subsequent RNAseq experiments, one employing nac7 RNAi leaves and the other using leaf protoplasts overexpressing Nac7, revealed an important role for NAC7 in regulating genes in photosynthesis, chlorophyll degradation and protein turnover pathways that each contribute to the functional stay‐green phenotype. We further determined the putative target of NAC7 and provided a logical extension for the role of NAC7 in regulating resource allocation from vegetative source to reproductive sink tissues. Collectively, our findings make a compelling case for NAC7 as a target for improving functional stay‐green and yields in maize and other crops.