Integrating single nuclei and bulk RNA sequencing in rice shoot apical meristems uncovers candidate early floral transition gene networks.

We describe transcriptional dynamics at the rice shoot apex by integrating time resolved single nuclei RNA-seq with bulk RNA-seq data. In rice, short days trigger floral transition and the transcriptional reprogramming of the shoot apex to become reproductive. We integrated time-resolved bulk RNA-seq with single nuclei RNA-seq analysis to gain a refined understanding of the transcriptional programs induced at the shoot apex during floral transition.

Rice florigens control a common set of genes at the shoot apical meristem including the F-BOX BROADER TILLER ANGLE 1 that regulates tiller angle and spikelet development.

Rice flowering is triggered by transcriptional reprogramming at the shoot apical meristem (SAM) mediated by florigenic proteins produced in leaves in response to changes in photoperiod. Florigens are more rapidly expressed under short days (SDs) compared to long days (LDs) and include the HEADING DATE 3a (Hd3a) and RICE FLOWERING LOCUS T1 (RFT1) phosphatidylethanolamine binding proteins. Hd3a and RFT1 are largely redundant at converting the SAM into an inflorescence, but whether they activate the same target genes and convey all photoperiodic information that modifies gene expression at the SAM is currently unclear.

Environmental control of rice flowering time.

Correct measurement of environmental parameters is fundamental for plant fitness and survival, as well as for timing developmental transitions, including the switch from vegetative to reproductive growth. Important parameters that affect flowering time include day length (photoperiod) and temperature. Their response pathways have been best described in Arabidopsis, which currently offers a detailed conceptual framework and serves as a comparison for other species.

Two florigens and a florigen-like protein form a triple regulatory module at the shoot apical meristem to promote reproductive transitions in rice.

Many plant species monitor and respond to changes in day length (photoperiod) for aligning reproduction with a favourable season. Day length is measured in leaves and, when appropriate, leads to the production of floral stimuli called florigens that are transmitted to the shoot apical meristem to initiate inflorescence development. Rice possesses two florigens encoded by HEADING DATE 3a (Hd3a) and RICE FLOWERING LOCUS T 1 (RFT1).

A transcription factor coordinating internode elongation and photoperiodic signals in rice.

In several plant species, inflorescence formation is accompanied by stem elongation. Both processes are accelerated in rice upon perception of shortening days. Here, we show that PREMATURE INTERNODE ELONGATION 1 (PINE1), encoding a rice zinc-finger transcription factor, reduces the sensitivity of the stem to gibberellin (GA).