Key laboratory of Molecular Epigenetics of Ministry of Education (MOE), Northeast Normal University, Changchun, 130024, China.
BMC Plant Biol. 2018 Jun 7;18(1):113. doi: 10.1186/s12870-018-1334-1.
It is known that hexaploid common wheat (Triticum aestivum L.) has stronger adaptability to many stressful environments than its tetraploid wheat progenitor. However, the physiological basis and evolutionary course to acquire these enhanced adaptabilities by common wheat remain understudied. Here, we aimed to investigate whether and by what means tolerance to low-nitrogen manifested by common wheat may emerge immediately following allohexaploidization.
We compared traits related to nitrogen (N) metabolism in a synthetic allohexaploid wheat (neo-6×, BBAADD) mimicking natural common wheat, together with its tetraploid (BBAA, 4×) and diploid (DD, 2×) parents. We found that, under low nitrogen condition, neo-6× maintained largely normal photosynthesis, higher shoot N accumulation, and better N assimilation than its 4× and 2× parents. We showed that multiple mechanisms underlie the enhanced tolerance to N-deficiency in neo-6×. At morphological level, neo-6× has higher root/shoot ratio of biomass than its parents, which might be an adaptive growth strategy as more roots feed less shoots with N, thereby enabling higher N accumulation in the shoots. At electrophysiological level, H efflux in neo-6× is higher than in its 4× parent. A stronger H efflux may enable a higher N uptake capacity of neo-6×. At gene expression level, neo-6× displayed markedly higher expression levels of critical genes involved in N uptake than both of its 4× and 2× parents.
This study documents that allohexaploid wheat can attain immediate higher tolerance to N-deficiency compared with both of its 4× and 2× parents, and which was accomplished via multiple mechanisms.
已知六倍体普通小麦（Triticum aestivum L.）比其四倍体小麦祖先更能适应许多胁迫环境。然而，普通小麦获得这些增强的适应能力的生理基础和进化过程仍未得到充分研究。在这里，我们旨在研究普通小麦的耐低氮性是否以及通过何种方式在异源六倍体化后立即表现出来。
我们比较了模拟天然普通小麦的合成异源六倍体小麦（neo-6×，BBAADD）与其四倍体（BBAA，4×）和二倍体（DD，2×）亲本在氮（N）代谢相关性状上的差异。我们发现，在低氮条件下，neo-6×的光合作用基本正常，地上部氮积累量较高，氮同化能力较强，优于其 4×和 2×亲本。我们表明，neo-6×对氮缺乏的耐受性增强是多种机制共同作用的结果。在形态水平上，neo-6×的根/茎生物量比其亲本更高，这可能是一种适应性生长策略，因为更多的根为较少的茎提供氮，从而使地上部积累更多的氮。在电生理水平上，neo-6×的 H 外排率高于其 4×亲本。更强的 H 外排可能使 neo-6×具有更高的氮吸收能力。在基因表达水平上，neo-6×的关键氮吸收基因的表达水平明显高于其 4×和 2×亲本。
本研究表明，与四倍体和二倍体亲本相比，异源六倍体小麦可以立即获得更高的耐氮性，这是通过多种机制实现的。
