Enhancing the photosynthetic induction response to fluctuating light has been suggested as a key target for improvement in crop breeding programs, with the potential to substantially increase whole canopy carbon assimilation and contribute to crop yield potential. Rubisco activation may be the main physiological process that will allow us to achieve such a goal. In this study, we assessed the phenotype of Rubisco activation rate in a doubled haploid (DH) barley mapping population [131 lines from a Yerong/Franklin (Y/F) cross] after a switch from moderate to saturating light. Rates of Rubisco activation were found to be highly variable across the mapping population, with a median activation rate of 0.1 min ^-1 in the slowest genotype and 0.74 min ^-1 in the fastest genotype. A unique QTL for Rubisco activation rate was identified on chromosome 7H. This is the first report on the identification of a QTL for Rubisco activation rate in planta and the discovery opens the door to marker assisted breeding to improve whole canopy photosynthesis of barley. This also suggests that genetic factors other than the previously characterised RCA isoforms on chromosome 4H control Rubisco activity. Further strength is given to this finding as this QTL colocalised with QTLs identified for steady state photosynthesis and stomatal conductance. Several other distinct QTLs were identified for these steady state traits, with a common overlapping QTL on chromosome 2H, and distinct QTLs for photosynthesis and stomatal conductance identified on chromosomes 4H and 5H respectively. Future work should aim to validate these QTLs under field conditions so that they can be used to aid plant breeding efforts.

中文翻译：

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大麦制图种群动态和稳态光合特性的QTLs鉴定

已经提出增强对波动光的光合作用诱导响应是改进作物育种计划的主要目标，具有显着增加整个冠层碳同化并有助于作物增产的潜力。Rubisco活化可能是使我们实现这一目标的主要生理过程。在这项研究中，我们评估了从中性光切换到饱和光后，双倍单倍体（DH）大麦作图群体[来自耶荣/富兰克林（Y / F）杂交的131系]的Rubisco活化率表型。在整个测绘人群中，Rubisco激活率变化很大，最慢的基因型中位激活率中位数为0.1 min ^-1，最慢基因型中位激活率为0.74 min ^-1最快的基因型。在7H染色体上鉴定出独特的Rubisco活化速率QTL。这是关于鉴定植物中Rubisco活化率的QTL的第一份报告这一发现为标记辅助育种打开了大门，以改善大麦的整个冠层光合作用。这也表明除了染色体4H上先前表征的RCA亚型以外的遗传因素还控制Rubisco活性。由于此QTL与为稳态光合作用和气孔导度而确定的QTL共定位，因此进一步增强了这一发现。针对这些稳态性状，还鉴定了其他几个不同的QTL，在2H染色体上有一个共同的重叠QTL，在4H和5H染色体上分别鉴定了用于光合作用和气孔电导的不同QTL。未来的工作应该旨在在田间条件下验证这些QTL，以便将其用于辅助植物育种工作。