Torada Atsushi, Koike Michiya, Ogawa Taiichi, Takenouchi Yu, Tadamura Kazuki, Wu Jianzhong, Matsumoto Takashi, Kawaura Kanako, Ogihara Yasunari
HOKUREN Agricultural Research Institute, Naganuma, Hokkaido 069-1317, Japan.
HOKUREN Agricultural Research Institute, Naganuma, Hokkaido 069-1317, Japan.
Curr Biol. 2016 Mar 21;26(6):782-7. doi: 10.1016/j.cub.2016.01.063. Epub 2016 Mar 3.
Seed germination under the appropriate environmental conditions is important both for plant species survival and for successful agriculture. Seed dormancy, which controls germination time, is one of the adaptation mechanisms and domestication traits [1]. Seed dormancy is generally defined as the absence of germination of a viable seed under conditions that are favorable for germination [2]. The seed dormancy of cultivated plants has generally been reduced during domestication [3]. Bread wheat (Triticum aestivum L.) is one of the most widely grown crops in the world. Weak dormancy may be an advantage for the productivity due to uniform emergence and a disadvantage for the risks of pre-harvest sprouting (PHS), which decreases grain quality and yield [4]. A number of quantitative trait loci (QTLs) controlling natural variation of seed dormancy have been identified on various chromosomes [5]. A major QTL for seed dormancy has been consistently detected on chromosome 4A [6-13]. The QTL was designated as a major gene, Phs1, which could be precisely mapped within a 2.6 cM region [14]. Here, we identified a mitogen-activated protein kinase kinase 3 (MKK3) gene (designated TaMKK3-A) by a map-based approach as a candidate gene for the seed dormancy locus Phs1 on chromosome 4A in bread wheat. Complementation analysis showed that transformation of a dormant wheat cultivar with the TaMKK3-A allele from a nondormant cultivar clearly reduced seed dormancy. Cultivars differing in dormancy had a single nonsynonymous amino acid substitution in the kinase domain of the predicted MKK3 protein sequence, which may be associated with the length of seed dormancy.
在适宜的环境条件下种子萌发对于植物物种的生存以及成功的农业生产都很重要。种子休眠控制着萌发时间，是适应机制和驯化性状之一[1]。种子休眠通常被定义为在有利于萌发的条件下有活力的种子不萌发[2]。栽培植物的种子休眠在驯化过程中通常有所降低[3]。面包小麦（Triticum aestivum L.）是世界上种植最广泛的作物之一。弱休眠可能因出苗均匀而对生产力有利，但对收获前发芽（PHS）风险不利，收获前发芽会降低谷物品质和产量[4]。已在各种染色体上鉴定出许多控制种子休眠自然变异的数量性状位点（QTL）[5]。在4A染色体上一直检测到一个控制种子休眠的主要QTL[6 - 13]。该QTL被指定为一个主要基因Phs1，它可以精确地定位在一个2.6 cM的区域内[14]。在这里，我们通过基于图谱的方法鉴定出一个丝裂原活化蛋白激酶激酶3（MKK3）基因（命名为TaMKK3 - A），作为面包小麦4A染色体上种子休眠位点Phs1的候选基因。互补分析表明，用来自非休眠品种的TaMKK3 - A等位基因转化休眠小麦品种明显降低了种子休眠。休眠不同的品种在预测的MKK3蛋白序列的激酶结构域中有一个单核苷酸非同义替换，这可能与种子休眠的时长有关。
