A QTL GN1.1, encoding FT-L1, regulates grain number and yield by modulating polar auxin transport in rice

Rice grain number is a crucial agronomic trait impacting yield. In this study, we characterized a quantitative trait locus(QTL), GRAIN NUMBER 1.1(GN1.1), which encodes a Flowering Locus T-like1(FT-L1) protein and acts as a negative regulator of grain number in rice. The elite allele GN1.1^(B),derived from the Oryza indica variety, BF3-104,exhibits a 14.6% increase in grain yield compared with the O. japonica variety, Nipponbare, based on plot yield tests. We demonstrated that GN1.1 interacted with and enhanced the stability of ADP-ribosylation factor(Arf)-GTPase-activating protein(Gap), OsZAC. Loss of function of OsZAC results in increased grain number. Based on our data, we propose that GN1.1^(B)facilitates the elevation of auxin content in young rice panicles by affecting polar auxin transport(PAT) through interaction with OsZAC. Our study unveils the pivotal role of the GN1.1 locus in rice panicle development and presents a novel, promising allele for enhancing rice grain yield through genetic improvement.

Anα/βhydrolase family member negatively regulates salt tolerance but promotes flowering through three distinct functions in rice

Ongoing soil salinization drastically threatens crop growth,development,and yield worldwide.It is therefore crucial that we improve salt tolerance in rice by exploiting natural genetic variation.However,many salt-responsive genes confer undesirable phenotypes and therefore cannot be effectively applied to practical agricultural production.In this study,we identified a quantitative trait locus for salt tolerance from the African rice species Oryza glaberrima and named it as Salt Tolerance and Heading Date 1(STH1).We found that STH1 regulates fatty acid metabolic homeostasis,probably by catalyzing the hydrolytic degradation of fatty acids,which contributes to salt tolerance.Meanwhile,we demonstrated that STH1 forms a protein complex with D3 and a vital regulatory factor in salt tolerance,OsHAL3,to regulate the protein abundance of OsHAL3 via the 26S proteasome pathway.Furthermore,we revealed that STH1 also serves as a co-activator with the floral integrator gene Heading date 1 to balance the expression of the florigen gene Heading date 3a under different circumstances,thus coordinating the regulation of salt tolerance and heading date.Notably,the allele of STH1 associated with enhanced salt tolerance and high yield is found in some African rice accessions but barely in Asian cultivars.Introgression of the STH1HP46 allele from African rice into modern rice cultivars is a desirable approach for boosting grain yield under salt stress.Collectively,our discoveries not only provide conceptual advances on the mechanisms of salt tolerance and synergetic regulation between salt tolerance and flowering time but also offer potential strategies to overcome the challenges resulted from increasingly serious soil salinization that many crops are facing.