Department of Plant Biology and Ecology, University of the Basque Country (UPV/EHU), E-48940, Leioa, Spain.
Ikerbasque, Basque Foundation for Science, E-48011, Bilbao, Spain.
New Phytol. 2022 Jun;234(5):1559-1565. doi: 10.1111/nph.18090. Epub 2022 Mar 26.
Agriculture faces the considerable challenge of having to adapt to a progressively changing climate (including the increase in CO levels and temperatures); environmental impact must be reduced while at the same time crop yields need to be maintained or increased to ensure food security. Under this scenario, increasing plants' nitrogen (N) use efficiency and minimizing the energy losses associated with photorespiration are two goals of crop breeding that are long sought after. The plastidic glutamine synthetase (GS2) enzyme stands at the crossroads of N assimilation and photorespiration, and is therefore a key candidate for the improvement of crop performance. The GS2 enzyme has long been considered essential for angiosperm survival under photorespiratory conditions. Surprisingly, in Arabidopsis GS2 is not essential for plant survival, and its absence confers tolerance towards ammonium stress, which is in conflict with the idea that NH accumulation is one of the main causes of ammonium stress. Altogether, it appears that the 'textbook' view of this enzyme must be revisited, especially regarding the degree to which it is essential for plant growth under photorespiratory conditions, and the role of NH assimilation during ammonium stress. In this article we open the debate on whether more or less GS2 is a desirable trait for plant productivity.
农业面临着巨大的挑战，需要适应不断变化的气候（包括 CO2 水平和温度的升高）；必须减少环境影响，同时保持或提高作物产量，以确保粮食安全。在这种情况下，提高植物的氮（N）利用效率和最小化与光呼吸相关的能量损失是作物培育长期追求的两个目标。质体谷氨酰胺合成酶（GS2）酶处于氮同化和光呼吸的交汇点，因此是提高作物性能的关键候选酶。GS2 酶长期以来被认为是在光呼吸条件下被子植物生存所必需的。令人惊讶的是，在拟南芥中，GS2 对植物的生存不是必需的，其缺失赋予了对铵胁迫的耐受性，这与 NH4+ 积累是铵胁迫的主要原因之一的观点相矛盾。总的来说，似乎必须重新审视对这种酶的“教科书”观点，特别是关于它在光呼吸条件下对植物生长的重要性程度，以及在铵胁迫期间 NH4+ 同化的作用。在本文中，我们就 GS2 酶的多少是植物生产力的理想特性展开了辩论。
