Abstract
Wheat spike development is a coordinated process of cell proliferation and differentiation with distinctive phases and architecture changes. However, the dynamic alteration of gene expression in this process remains enigmatic. Here, we characterized and dissected bread wheat spike into six developmental stages, and used genome-wide gene expression profiling, to investigate the underlying regulatory mechanisms. High gene expression correlations between any two given stages indicated that wheat early spike development is controlled by a small subset of genes. Throughout, auxin signaling increased, while cytokinin signaling decreased. Besides, many genes associated with stress responses highly expressed during the double ridge stage. Among the differentially expressed genes (DEGs), were identified 375 transcription factor (TF) genes, of which some homologs in rice or Arabidopsis are proposed to function in meristem maintenance, flowering time, meristem initiation or transition, floral organ development or response to stress. Gene expression profiling demonstrated that these genes had either similar or distinct expression pattern in wheat. Several genes regulating spike development were expressed in the early spike, of which Earliness per se 3 (Eps-3) was found might function in the initiation of spikelet meristem. Our study helps uncover important genes associated with apical meristem morphology and development in wheat.
Highlights
Terminate or abort after generating a series of branch meristems (BMs) that give rise to secondary branch meristems (SBMs) or spikelet meristems (SMs), followed by the initiation of FMs5
It was worth noting that we collected the tissues before floral organogenesis and, the samples consisted of meristematic cells from shoot apical meristem (SAM), inflorescence meristem (IM), SM and FMs as well as a few differentiated cells that have little impact on the consequent data analysis
From vegetative stage to floret differentiation stage, the young spike undergoes the transition from SAM to IM, and the initiation of spikelet meristem and floral meristem, sequentially
Summary
Terminate or abort after generating a series of branch meristems (BMs) that give rise to secondary branch meristems (SBMs) or spikelet meristems (SMs), followed by the initiation of FMs5. The reference sequences of natural hexaploid wheat (Chinese Spring) and the A and D donor genomes have been generated[10,14,15] These genomic resources permit comparative and evolutionary analyses with closely related species such as rice and Brachypodium[16], and make it much easier to dissect the molecular mechanisms underlying important developmental processes in wheat. Studies of high throughput gene expression profiling in wheat relied on DNA microarray technologies with probes corresponding to unigenes from the publicly available expressed sequence tag (EST) resources[17,18] This method was relatively low throughput and high cost and suffered from deviation in the quantitative analysis[19]. By providing a broad view of dynamic genome-wide gene expression in early wheat spike development, our results help uncover important genes associated with apical meristem morphology and development in wheat
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