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Summary: Drought is a deleterious abiotic stress factor that constrains crop growth and development. Post‐translational modification of proteins mediated by the ubiquitin–proteasome system is an effective strategy for directing plant responses to stress, but the regulatory mechanisms in wheat remain unclear. In this study, we showed that TaSDIR1‐4A is a positive modulator of the drought response. Overexpression of TaSDIR1‐4A increased the hypersensitivity of stomata, root length and endogenous abscisic acid (ABA) content under drought conditions. TaSDIR1‐4A encodes a C3H2C3‐type RING finger protein with E3 ligase activity. Amino acid mutation in its conserved domain led to loss of activity and altered the subcellular localization. The membrane‐bound transcription factor TaWRKY29 was identified by yeast two‐hybrid screening, and it was confirmed as interacting with TaSDIR1‐4A both in vivo and in vitro. TaSDIR1‐4A mediated the polyubiquitination and proteolysis of the C‐terminal amino acid of TaWRKY29, and its translocation from the plasma membrane to the nucleus. Activated TaWRKY29 bound to the TaABI5 promoter to stimulate its expression, thereby positively regulating the ABA signalling pathway and drought response. Our findings demonstrate the positive role of TaSDIR1‐4A in drought tolerance and provide new insights into the involvement of UPS in the wheat stress response. [ABSTRACT FROM AUTHOR]

9012AB, a recessive genic male sterility (RGMS) line derived from spontaneous mutation in Brassica napus, has been playing an important role in rapeseed hybrid production in China. The male sterility of 9012AB is controlled by two recessive genes (ms3 and ms4) interacting with one recessive epistatic suppressor gene (esp). The objective of this study was to develop PCR-based markers tightly linked to the esp gene and construct a high-resolution map surrounding the esp gene. From the survey of 512 AFLP primer combinations, 3 tightly linked AFLP markers were obtained and successfully converted to codominant or dominant SCAR markers. Furthermore, a codominant SSR marker (Ra2G08) associated with the esp gene was identified through genetic map integration. For fine mapping of the esp gene, these PCR-based markers were analyzed in a large [BC.sub.1] population of 2545 plants. The esp gene was then genetically restricted to a region of 1.03 cM, 0.35 cM from SSR marker Ra2G08 and 0.68 cM from SCAR marker WSC6. The SCAR marker WSCS co-segregated with the target gene. These results lay a solid foundation for map-based cloning of esp and will facilitate the selection of RGMS lines and their temporary maintainers. Key words: Brassica napus, recessive genic male sterility, epistatic suppressor gene, fine mapping, map-based cloning. La lignee 9012AB, une lignee presentant une androsterilite genique recessive (RGMS) a deux composantes, a ete obtenue par mutation spontanee chez le Brassica napus et joue un role important en production de colza hybride en Chine. L'androsterilite chez 9012AB est controlee par deux genes recessvvs (ms3 et ms4) qui interagissent avec un gene suppresseur epistatique recessif (esp). L'objectif de cette etude etait de developper des marqueurs PCR etroitement lies au gene esp et de produire une carte genetique a haute resolution author de ce gene. Suite a fexamen de 512 combinations d'amorces AFLP, trois marqueurs etroitement lies ont ete obtenus et converts en marqueurs SCAR dominants ou codominants. De plus, un marqueur microsatellite co-dominant associe au gene esp, Ra2G08, a ete identifie suite a fintegration de caries genetiques. Pour la cartographie fine du gene esp, ces marqueurs PCR ont ete analyses sur une grande population [BC.sub.1] composee de 2545 plantes. Le gene esp a ete positionne au sein d'un intervalle genetique de 1,03 cM, a 0,35 cM du marqueur microsatellite Ra2G08 et a 0,68 cM du marqueur SCAR WSC6. Le marqueur SCAR WSCS affichait une co-segregation parfaite avec le gene cible. Ces resultats fournissent une assise solide en vue du clonage positionnel du gene esp et faciliteront la selection de lignees RGMS et de leurs lignees de maintaen temporary. Mots-cles : Brassica napus, androsterilite genique recessive, gene suppresseur epistatique, cartographie fme, clonage positionnel. [Traduit nar la Redaction], Introduction It is widely accepted that recessive genic male sterility (RGMS) systems have great potential in rapeseed heterosis utilization because of their stable and complete sterility, extensive distribution of restorers, [...]