Salter William T, Li Si, Dracatos Peter M, Barbour Margaret M
School of Life and Environmental Sciences, Sydney Institute of Agriculture, The University of Sydney, Brownlow Hill, NSW, Australia.
Plant Breeding Institute, The University of Sydney, Cobbitty, NSW, Australia.
AoB Plants. 2020 Nov 24;12(6):plaa063. doi: 10.1093/aobpla/plaa063. eCollection 2020 Dec.
Enhancing the photosynthetic induction response to fluctuating light has been suggested as a key target for improvement in crop breeding programmes, 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 in the slowest genotype and 0.74 min in the fastest genotype. A unique quantitative trait locus (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 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 characterized Rubisco activase (RCA) isoforms on chromosome 4H control Rubisco activity. Further strength is given to this finding as this QTL co-localized 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.
增强对波动光的光合诱导响应已被认为是作物育种计划中改善的关键目标，有可能大幅提高全冠层碳同化并有助于提高作物产量潜力。核酮糖-1,5-二磷酸羧化酶/加氧酶（Rubisco）激活可能是使我们实现这一目标的主要生理过程。在本研究中，我们评估了一个加倍单倍体（DH）大麦作图群体[来自耶荣/富兰克林（Y/F）杂交的131个株系]在从适度光照转换为饱和光照后Rubisco激活率的表型。发现Rubisco激活率在整个作图群体中高度可变，最慢基因型的激活率中位数为0.1分钟，最快基因型的激活率中位数为0.74分钟。在7H染色体上鉴定出一个独特的Rubisco激活率数量性状位点（QTL）。这是关于Rubisco激活率QTL鉴定的首次报道，这一发现为通过标记辅助育种提高大麦全冠层光合作用打开了大门。这也表明，除了先前在4H染色体上表征的Rubisco活化酶（RCA）同工型之外，还有其他遗传因素控制Rubisco活性。由于该QTL与为稳态光合作用和气孔导度鉴定的QTL共定位，这一发现得到了进一步的支持。还为这些稳态性状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，分别在4H和5H染色体上鉴定出了光合作用和气孔导度的不同QTL。未来的工作应旨在在田间条件下验证这些QTL，以便它们可用于辅助植物育种工作。
