The Elite Alleles of OsSPL4 Regulate Grain Size and Increase Grain Yield in Rice

Abstract

Grain weight and grain number, the two important yield traits, are mainly determined by grain size and panicle architecture in rice. Herein, we report the identification and functional analysis of OsSPL4 in panicle and grain development of rice. Using CRISPR/Cas9 system, two elite alleles of OsSPL4 were obtained, which exhibited an increasing number of grains per panicle and grain size, resulting in increase of rice yield. Cytological analysis showed that OsSPL4 could regulate spikelet development by promoting cell division. The results of RNA-seq and qRT-PCR validations also demonstrated that several MADS-box and cell-cycle genes were up-regulated in the mutation lines. Co-expression network revealed that many yield-related genes were involved in the regulation network of OsSPL4. In addition, OsSPL4 could be cleaved by the osa-miR156 in vivo, and the OsmiR156-OsSPL4 module might regulate the grain size in rice. Further analysis indicated that the large-grain allele of OsSPL4 in indica rice might introgress from aus varieties under artificial selection. Taken together, our findings suggested that OsSPL4 could be as a key regulator of grain size by acting on cell division control and provided a strategy for panicle architecture and grain size modification for yield improvement in rice.

Conservation and Divergence of SQUAMOSA-PROMOTER BINDING PROTEIN-LIKE (SPL) Gene Family between Wheat and Rice

“…The previous study has shown that the most recent whole-genome duplication in rice has led to five duplicated pairs of OsSPL genes (pair 1: OsSPL3/12; pair 2: OsSPL4/11; pair 3: OsSPL5/10; pair 4: OsSPL14/17; and pair 5: OsSPL16/18). All five OsSPL pairs are retained and exhibit partially redundant functions and evidence for neofunctionalization [5,10,13,14,31,33,37,50,69]. For example, OsSPL3 knockout altered the heading date, whereas OsSPL12 knockout did not; OsSPL4 knockout altered the heading date, whereas OsSPL11 knockout did not; OsSPL5 knockout changed the tiller number, whereas OsSPL10 knockout did not [31].…”

“…Therefore, comparisons between OsSPLs and TaSPLs, in the aspects of gene orthology, expression patterns, and functions may indicate the functions of TaSPL genes, thus helping to prioritize the TaSPL genes for detailed genetic and functional studies. To this end, we collected the known functions of OsSPL genes based on previous reports [5,6,11,13,14,[30][31][32][33][34][35][36][37]44,69] (Table S5). Consistent with the observations that most Os-SPL genes are widely expressed in several organs-including leaves, stems, inflorescences, and seeds-with expression preferences in certain tissues and stages (Figure S7), several published investigations have revealed the pleiotropic functions of OsSPLs, and the complex functional redundancy between the OsSPL members (summarized in Table S5).…”

Hormone analysis and candidate genes identification associated with seed size in Camellia oleifera

“…Among the screened hub genes, the SPL gene family plays an important role in plant growth and increases crop yield by regulating the architecture of rice plants [ 63 , 64 ]. In rice, SPL4 could be a key regulator of grain size by acting on cell division control to improve rice yield and the overexpression of SPL4 decreased grain weight and size [ 65 ]. Seed-specific overexpression of SPL12 and plant Architecture 1 ( IPA1 ) enhance seed improved seed dormancy grain size in rice [ 66 ].…”

Genetic and molecular pathways controlling rice inflorescence architecture

“…DEP1 , DEP2 and DEP3 also influence grain size apart from inflorescence architecture ( Huang et al., 2009 ; Li et al., 2010 ; Qiao et al., 2011 ). Knockout of OsSPL4 or overexpression of OsSPL13 enlarges both inflorescences and grains ( Si et al., 2016 ; Hu et al., 2021b ). The loss of function of MOC1 , LAX1 , and LAX2 simultaneously reduces the number of tillers and panicle branches ( Komatsu et al., 2001 ; Li et al., 2003 ; Tabuchi et al., 2011 ).…”