Natural Variation of StNADC Regulates Plant Senescence in Tetraploid Potatoes (Solanum tuberosum L.)

Senescence impacts plant growth and yields in tetraploid potatoes (<i>Solanum tuberosum</i> L.). Because of their homogenous tetraploid features, it is a major challenge to understand the genetic basis and molecular mechanisms of senescence. Here, we identified a novel central senescence regulator (Nicotinate-nucleotide pyrophosphorylase QPT/<i>StNADC</i>) through map-based cloning. Overexpression of <i>StNADC</i>^Z3 accelerated senescence in the late-senescence variety, with NAD content declining by around 40%. CRISPR/Cas9-induced <i>StNADC</i> mutant <i>cr2-11</i> exhibited extremely early senescence, and the NAD content was reduced by 87% along with reduced chlorophyll content and photosynthesis. Moreover, the downstream products of the NAD synthesis pathway, such as NaMN, NAD, or niacin, can refresh the <i>cr2-11</i> mutant to grow normally. Further, the transcriptomics and metabolomics data unveiled that the disrupting of <i>StNADC</i> impairs NAD metabolism, accelerating plant senescence through multiple biological levels. Our results show that <i>StNADC</i> is indispensable for NAD synthesis, and targeting the <i>StNADC</i>-mediated NAD synthesis pathway could be a useful strategy to regulate senescence in potato breeding preprograms.