Trends in Plant Science
Volume 22, Issue 8, August 2017, Pages 643-646
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Boosting Rice Yield by Fine-Tuning SPL Gene Expression

https://doi.org/10.1016/j.tplants.2017.06.004Get rights and content

Plant architecture is an important determinant of crop yield. Recent studies showed that SPL family genes regulate the architecture of rice plants. SPLs inhibit tillering in general, but promote panicle branching at optimal expression levels to increase grain number. Fine-tuning the expression of SPL genes may provide useful strategies for crop improvement.

Section snippets

SPL Genes Play Major Roles in Plant Development

IPA1 encodes Oryza sativa (Os)SPL14, a member of the SQUAMOSA PROMOTER BINDING PROTEIN (SBP)-like (SPL) family of plant-specific transcription factors that all contain a highly conserved DNA-binding domain (SBP domain) of ∼76 amino acids in length [4]. Since the identification of the first two members AmSBP1 and AmSBP2 in snapdragon (Antirrhinum majus), SPL genes have been found in nearly all plant species including algae and moss [4].

It is now known that some SPL genes are regulated by

SPL Genes Have Multiple Roles in Rice Yield

In 2010, two groups from China and Japan independently reported the function of OsSPL14 identified by quantitative trait locus (QTL) cloning, and named the locus IPA1 and WFP (Wealthy Farmer’s Panicle), respectively. The variants of OsSPL14 dampened tiller branching, but increased panicle branching and grain weight together with stronger culms 6, 7. Functional analysis showed that IPA1 had a point mutation in the recognition site for miR156/157/529, while WFP changed epigenetic modification in

Exploring the Expression Dosage Effects of SPL Genes for Crop Improvement

Wang et al. proposed that fine-tuning SPL gene expression may provide a strategy for increasing rice productivity in breeding [5]. The available data from functional tests of SPL genes are in agreement with the idea of fine-tuning strategy (Figure 1B–E).

For example, compared to the previously reported IPA1 allele (renamed ipa1-1D) [6], ipa1-2D is weaker in promoting OsSPL14 expression. However, such weaker expression results in plants with an optimal combination of tiller number and panicle

Concluding Remarks

While the functions of other SPL genes still need to be tested, the findings so far have important implications in breeding applications in rice. The desirable alleles can be used directly to improve rice yield by traditional crossing approach, with or without marker-assisted selection. Gene-editing technology such as CRISPR/Cas9 can be used to modify the regulatory regions or miRNA recognition sites of SPL genes to modify their expression patterns/levels to create novel mutations for desirable

Acknowledgments

L.W. is supported by a grant from the China Postdoctoral Science Foundation (2016M590699); Q.Z. is supported by a grant from the National Key Research and Development Program (2016YFD0100903).

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