3.3 Limited transcriptomic change induced by
eCO2 than by N application rate
To understand the underlying transcriptional changes in response to the
eCO2, we employed RNA sequencing approach to compare the
gene expression profiles of tissues near the SAM (where the tiller was
about to appear) and the third true leaf at leaf-age four. The total
number of DEG introduced by tissue type (leaf and SAM), N application
rate (N0 and N10), and CO2 treatment (ambient
CO2 and eCO2) were strikingly different
(Fig. 4A). Tissue had the highest effect, followed by N application
rate, and eCO2. The N application had more influences on
leaf than SAM, similar to the impact of CO2 (Fig. 4A).
Using the Venn diagram, we found that the universal DEG (commonly
altered genes) introduced by tissue was the most (11221, Fig. 4B),
followed by N application rate (197, Fig. 4C), and lastly by
CO2 effect (5, Fig. 4D). These numbers indicated that
the global gene expression profile was overwhelmingly defined by the
tissue type, only being altered at limited range by N application rate,
and at a very narrow scope by [CO2].