Abstract
The phytohormone gibberellic acid (GA) has essential signaling functions in multiple processes during plant development. In the “Green Revolution”, breeders developed high-yield rice cultivars that exhibited both semi-dwarfism and altered GA responses, thus improving grain production. Most studies of GA have concentrated on germination and cell elongation, but GA also has a pivotal role in floral organ development, particularly in stamen/anther formation. In rice, GA signaling plays an important role in spikelet fertility; however, the molecular genetic and biochemical mechanisms of GA in male fertility remain largely unknown. Here, we review recent progress in understanding the network of GA signaling and its connection with spikelet fertility, which is tightly associated with grain productivity in cereal crops.
Highlights
The phytohormone gibberellic acid (GA; referred to as gibberellin) regulates almost all processes of plant development and growth, including seed development and germination, stem and root growth, cell division, and flowering time
We describe recent progress in revealing the molecular mechanisms of GA signaling in stamen/anther development and spikelet fertility in rice
It will be crucial to maintain the balance of agronomic traits; for instance, excessive tillering often gives rise to a decrease in grain production, because tillers can contend with the main culm for resources and negatively affect seed filling rate [56]
Summary
The phytohormone gibberellic acid (GA; referred to as gibberellin) regulates almost all processes of plant development and growth, including seed development and germination, stem and root growth, cell division, and flowering time. Several factors involved in GA signaling have high protein sequence similarity and play similar roles in stamen development in Arabidopsis and rice, which indicates the existence of a conserved pathway in stamen/anther development in angiosperms [15,16,17,18]. In rice, (see schematic in Figure 1) the DELLA protein SLENDER RICE1 (SLR1) negatively regulates downstream genes in the GA signaling pathway, Int. J. DELLA protein SLENDER RICE1 (SLR1) negatively regulates downstream genes in the GA signaling pathway, including GAMYB, which encodes a transcription factor that positively irnecgluuldaitnegs GGAA-MreYspBo, nwsihviechgeennecso(dTeasbalet1ra) n[1s2cr,2ip1,t2io2n]. The degradation of SLR1, caused by GA perception, de-represses the transcription of downstream genes in the GA signaling pathway (Figure 1). 625 aa 354 aa 212 aa 707 aa 553 aa 927aa a Data from Michigan State University; b Data from Rice Genome Annotation Project
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