Developmental Genetic Mechanisms of C4 Syndrome Based on Transcriptome Analysis of C3 Cotyledons and C4 Assimilating Shoots in Haloxylon ammodendron.

It is believed that transferring the C₄ engine into C₃ crops will greatly increase the yields of major C₃ crops. Many efforts have been made since the 1960s, but relatively little success has been achieved because C₄plant traits, referred to collectively as C₄ syndrome, are very complex, and little is known about the genetic mechanisms involved. Unfortunately, there exists no ideal genetic model system to study C₄ syndrome. It was previously reported that the Haloxylon species have different photosynthetic pathways in different photosynthetic organs, cotyledons and assimilating shoots. Here, we took advantage of the developmental switch from the C₃ to the C₄ pathway to study the genetic mechanisms behind this natural transition. We compared the transcriptomes of cotyledons and assimilating shoots using mRNA-Seq to gain insight into the molecular and cellular events associated with C₄ syndrome. A total of 2959 differentially expressed genes [FDR≤0.001 and abs (|log₂(Fold change)|≥1)] were identified, revealing that the transcriptomes of cotyledons and assimilating shoots are considerably different. We further identified a set of putative regulators of C₄ syndrome. This study expands our understanding of the development of C₄ syndrome and provides a new model system for future studies on the C₃-to- C₄ switch mechanism. [ABSTRACT FROM AUTHOR]