biostudies-literatureSaiz-Perez JEuropean Molecular Biology OrganizationMCIU/AEI/10.13039/501100011033 and EU FEDERMCIN/AEI/10.13039/501100011033Universidad de Castilla-La ManchaFonds Wetenschappelijk OnderzoekChinese Scholarship CouncilJunta de Comunidades de Castilla-La Mancha and EU FEDER672-689https://www.ebi.ac.uk/biostudies/studies/S-EPMC12445817biostudies-literatureUnknown248(2)Stomatal abundance decrease in Arabidopsis triggered by warm temperature is attributed to PIF4-mediated repression of SPEECHLESS (SPCH) expression. We identified the unknown developmental and transcriptional basis of this adaptive response. We traced stomatal lineages in vivo using cell-identity marker lines and mutants, quantified epidermal traits, and conducted RNA sequencing under oscillating temperatures. Prolonged warm temperature or PIF4-overexpression altered cell fates, inducing diverted stomatal precursors (DPs) that lacked stomatal fate, contributing to stomata reduction. DPs originated from meristemoids that lost SPCH expression, lacked MUTE expression, and exited the cell cycle. Short warm-temperature pulses allowed later recovery of SPCH expression and did not induce DPs or stThe New phytologistWarm temperature modifies cell fates to reduce stomata production in Arabidopsis.PMC124458179227PID2021-123319NB-1001222221NSBPLY/21/180225/000058G003720NPID2022-137606NB-I00PID2019-105362RB-I00Sterck LIllescas-Miranda JKim EJDesvoyes BVuylsteke MFenoll CBaekelandt AGutierrez CRussinova EGuo BSaiz-Perez JMena MfalseWarm temperature modifies cell fates to reduce stomata production in Arabidopsis.Stomatal abundance decrease in Arabidopsis triggered by warm temperature is attributed to PIF4-mediated repression of SPEECHLESS (SPCH) expression. We identified the unknown developmental and transcriptional basis of this adaptive response. We traced stomatal lineages in vivo using cell-identity marker lines and mutants, quantified epidermal traits, and conducted RNA sequencing under oscillating temperatures. Prolonged warm temperature or PIF4-overexpression altered cell fates, inducing diverted stomatal precursors (DPs) that lacked stomatal fate, contributing to stomata reduction. DPs originated from meristemoids that lost SPCH expression, lacked MUTE expression, and exited the cell cycle. Short warm-temperature pulses allowed later recovery of SPCH expression and did not induce DPs or st2025-01-01T00:00:00Z2025 Oct2026-07-15T14:20:33.499Z2026-07-05T03:12:19.487ZS-EPMC124458174071602710.1111/nph.70396