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

ABSTRACT Rice grain number is a crucial agronomic trait impacting yield. In this study, we characterized a quantitative trait locus (QTL), <italic>GRAIN NUMBER 1.1</italic> (<italic>GN1.1</italic>), which encodes a Flowering Locus T‐like1 (FT‐L1) protein and acts as a negative regulator of grain number in rice. The elite allele <italic>GN1.1</italic><italic>B</italic>, derived from the <italic>Oryza indica</italic> variety, BF3‐104, exhibits a 14.6% increase in grain yield compared with the <italic>O. japonica</italic> 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 <italic>OsZAC</italic> results in increased grain number. Based on our data, we propose that <italic>GN1.1</italic><italic>B</italic> facilitates the elevation of auxin content in young rice panicles by affecting polar auxin transport (PAT) through interaction with <italic>OsZAC</italic>. Our study unveils the pivotal role of the <italic>GN1.1</italic> locus in rice panicle development and presents a novel, promising allele for enhancing rice grain yield through genetic improvement. [ABSTRACT FROM AUTHOR]