Five OsS40 Family Members Are Identified as Senescence-Related Genes in Rice by Reverse Genetics Approach

Abstract

A total of 16 OsS40 genes of Oryza sativa were identified in our previous work, but their functions remain unclear. In this study, 13 OsS40 members were knocked out using the CRISPR/cas9 gene-editing technology. After screening phenotype characterization of CRISPR/Cas9 mutants compared to WT, five oss40s mutants exhibited a stay-green phenotype at 30 days after heading. Moreover, increased grain size and grain weight occurred in the oss40-1, oss40-12, and oss40-14 lines, while declined grain weight appeared in the oss40-7 and oss40-13 mutants. The transcript levels of several senescence-associated genes (SAGs), chlorophyll degradation-related genes (CDGs), as well as WRKY members were differentially decreased in the five stay-green oss40s mutants compared to WT. Five oss40 mutants also exhibited a stay-green phenotype when the detached leaves were incubated under darkness for 4 days. OsSWEET4 and OsSWEET1b were significantly upregulated, while OsSWEET1a and OsSWEET13 were significantly downregulated in both oss40-7 and oss40-14 compared to WT. Furthermore, these five OsS40 displayed strong transcriptional activation activity and were located in the nucleus. Most of the OsS40 genes were downregulated in the oss40-1, oss40-7, and oss40-12 mutants, but upregulated in the oss40-13 and oss40-14 mutants, indicating coordinated regulation among OsS40 members. These results suggest that OsS40-1, OsS40-7, OsS40-12, OsS40-13, and OsS40-14 are senescence-associated genes, involved in the senescence and carbon allocation network by modulating other OsS40 members, SWEET member genes, and senescence-related gene expression.

Allele-specific hormone dynamics in highly transgressive F2 biomass segregants in sugarcane (Saccharum species)

“…Down-regulation of owering related genes i.e., FLOWERING PROMOTING FACTOR 1 (FPF1), EARLY FLOWERING 3 (ELF3), and AGAMOUS-LIKE MADS-BOX PROTEIN (AGL12, SVP) support late maturing, higher biomass and sugars in HB genotypes. Leaf senescence is an important terminal stage of plant development after reproductive phase, senescence related NAC transcription factors and a newly identi ed S-40 gene family also showed down-regulation [52,53]. The expression levels of owering and senescence related genes support the notion that HB genotypes undergo extended vegetative phase and delayed reproductive maturity.…”

The transcription factor CsS40 negatively regulates TCS1 expression and caffeine biosynthesis in connection to leaf senescence in Camellia sinensis

“…However, other studies showed that S40 protein promoted leaf senescence. Rice OsS40 have been shown to play a role in carbon allocation and leaf senescence in Oryza sativa by modulating the expression of SWEET sugar transporter genes and other senescence-related genes [ 34 ]. Barley HvS40 was used as a biomarker of senescence by playing as a key upstream regulator of a well-known senescence gene SAG expression [ 35 ].…”

Multiple Layers of Regulation on Leaf Senescence: New Advances and Perspectives

“…With the aid of forwarding or reversing genetics strategies and the development of multi-functional CRISPR genome editing technology, a large number of senescence-related mutants will be generated. For example, quintuple mutants of oss40s-cr generated using CRISPR technology displays stay-green phenotypes ( Habiba et al, 2021 ), which will further deepen our understanding of leaf senescence. The model plant Arabidopsis has played an important role in revealing the molecular or genetic regulation mechanisms of plant senescence, but we still know little about leaf senescence and do not fully understand the biological significance of senescence ( Lim et al, 2007 ).…”