Endogenous signals are also necessary to initiate flowering during inductive conditions
Transcriptomic analysis also showed an increased expression of genes involved in gibberellin synthesis in the leaf samples associated with flowering tillers. Previous studies have already shown that gibberellin is able to initiate and accelerate flowering in Chionochloa sp.in the glasshouse (Martin, Jameson, Mark, Yeung, & Pharis, 1993) and the field (Turnbull et al., 2012). Gibberellin has also been shown to upregulate the expression of FT and SOC1 independently of the photoperiodic pathway in Arabidopsis and several temperate cereals as well (Yu et al., 2012). Greater expression of gibberellin synthesis gene(s) may have promoted flowering in C. pallens by escalating the expression of CpATFL1 and CpMADS1 as observed in the transcriptomic studies. Along with gibberellin, expression of the sugar signalling genes, CpUGT87A2 , CpTPS1 and CpHXK1 , was found to be significantly greater in the leaves of the tillers that flowered in the next season. Appropriate sugar levels are required as an internal standard for a plant to respond to environmental signals to induce the floral transition (Yang, Xu, Koo, He, & Poethig, 2013).
These data emphasise that, along with the external signals, C. pallens may require sufficient internal signals to respond and initiate the floral transition. This may explain why certain tillers in the experimental transplants did not undergo flowering even following the perception of an external cue such as warm summer temperatures. These vegetative tillers may be either too young or may be still in process of accumulating enough resources.