Abstract
Early
flowering is a survival strategy in wheat (Triticum aestivum L.)
that sacrifices grain yield under long photoperiod conditions, and this
contradiction is greatly affected by floral growth and development.
However,
little is known about the regulatory mechanisms that remove the barrier
between “early flowering” and “high yielding” during floret
development. Here, we showed high-resolution analyses of the number and
morphology of floret primordia and the transcriptomes of wheat spikes in
three light
regimens.
The development of all floret primordia in a spike could be divided into
four distinct stages: differentiation (Stage I), differentiation and
morphology development concurrently (Stage II), morphology development
(Stage III), and polarization (Stage IV).
Compared
to the controls, the long photoperiod supplemented with red light
treatment shortened the time required to complete Stage I-II, then
improved assimilates in the spike and promoted anther development,
thereby increasing fertile floret primordia during Stage III, and
maintained fertile floret primordia development during Stage IV until
they became fertile florets (grains) via a dynamic gene network centered
on ubiquitin, calcium signaling, aldehyde dehydrogenase, zinc finger
proteins, and heat shock proteins. Our findings proposed a light
regimen, critical stages, and candidate regulators that promoted early
flowering and high yield in wheat.
KEY WORDS: assimilate partitioning,
floret
development, fertile florets number, flowering time, LED light,
transcriptomics.