A missense mutation in a large subunit of ribonucleotide reductase confers temperature-gated tassel formation
A missense mutation in a large subunit of ribonucleotide reductase confers temperature-gated tassel formation
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核糖核苷酸还原酶大亚基的错义突变导致温度门控雄穗形成
DOI：
10.1104/pp.20.00219
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发表时间：
2020
期刊：
影响因子：
7.4
通讯作者：
Weiwei Jin
中科院分区：
文献类型：
--
作者：
Shiyi Xie;Hongbing Luo;Yumin Huang;Yaxin Wang;Wei Ru;Yunlu Shi;Wei Huang;Hai Wang;Zhaobin Dong;Weiwei Jin
温度是调节植物生长的主要因素。为了在极端温度下繁殖，植物必须在暴露于温度变化时发育正常的生殖器官。然而，人们对其潜在的分子机制知之甚少。本研究鉴定了玉米（Zea mays）突变热敏消失雄穗1- r (tvt1-R)，该突变体在高温（限制性）下由于茎尖分生组织（SAM）阻滞而缺乏雄穗，但在中等（允许）温度下形成正常的雄穗。表型转化intv1 - mutants的关键阶段是V2到V6 （Vn，其中“n”是可见有项圈的叶片的数量）。定位克隆、等位基因和互补测试表明，在核糖核苷酸还原酶（RNR）大亚基（RNRL） ZmRNRL1中，G-to-A突变导致arg277 - his277取代，从而导致tvt1突变表型。RNR调节脱氧核糖核苷三磷酸（dNTP）的生产速率，用于DNA复制和损伤修复。通过表达、酵母双杂交、RNA测序和流式细胞分析，我们发现zmrnrl1 -tvt1- r在34°C时由于arg277 - his277取代而无法与所有三个RNR小亚基相互作用，这可能阻碍RNR全酶（α2β2）的形成，从而减少DNA复制所需的dNTP供应。对于需要连续、充足的dNTP供应以进行快速分裂的SAM来说，dNTP供应的减少可能尤其严重，正如限制温度下的SAM停滞和vt1突变体的流苏缺失所证明的那样。我们的研究揭示了玉米温度门控雄穗形成的新机制，并为RNRL在SAM维持中的作用提供了新的见解。
Temperature is a major factor regulating plant growth. To reproduce at extreme temperatures, plants must develop normal reproductive organs when exposed to temperature changes. However, little is known about the underlying molecular mechanisms. Here, we identified the maize (Zea mays) mutantthermosensitive vanishing tassel1-R(tvt1-R), which lacks tassels at high (restrictive) temperatures due to shoot apical meristem (SAM) arrest, but forms normal tassels at moderate (permissive) temperatures. The critical stage for phenotypic conversion intvt1-Rmutants is V2 to V6 (Vn, where “n” is the number of leaves with collars visible). Positional cloning and allelism and complementation tests revealed that a G-to-A mutation causing a Arg277-to-His277substitution in ZmRNRL1, a ribonucleotide reductase (RNR) large subunit (RNRL), confers thetvt1-Rmutant phenotype. RNR regulates the rate of deoxyribonucleoside triphosphate (dNTP) production for DNA replication and damage repair. By expression, yeast two-hybrid, RNA sequencing, and flow cytometric analyses, we found that ZmRNRL1-tvt1-Rfailed to interact with all three RNR small subunits at 34°C due to the Arg277-to-His277substitution, which could impede RNR holoenzyme (α2β2) formation, thereby decreasing the dNTP supply for DNA replication. Decreased dNTP supply may be especially severe for the SAM that requires a continuous, sufficient dNTP supply for rapid division, as demonstrated by the SAM arrest and tassel absence intvt1-Rmutants at restrictive temperatures. Our study reveals a novel mechanism of temperature-gated tassel formation in maize and provides insight into the role of RNRL in SAM maintenance.