Arabidopsis AtHB7 and AtHB12evolved divergently to fine tune processes associated with growth and responses to water stress

Abstract

BackgroundArabidopsis AtHB7 and AtHB12 transcription factors (TFs) belong to the homeodomain-leucine zipper subfamily I (HD-Zip I) and present 62% amino acid identity. These TFs have been associated with the control of plant development and abiotic stress responses; however, at present it is not completely understood how AtHB7 and AtHB12 regulate these processes.ResultsBy using different expression analysis approaches, we found that AtHB12 is expressed at higher levels during early Arabidopsis thaliana development whereas AtHB7 during later developmental stages. Moreover, by analysing gene expression in single and double Arabidopsis mutants and in transgenic plants ectopically expressing these TFs, we discovered a complex mechanism dependent on the plant developmental stage and in which AtHB7 and AtHB12 affect the expression of each other. Phenotypic analysis of transgenic plants revealed that AtHB12 induces root elongation and leaf development in young plants under standard growth conditions, and seed production in water-stressed plants. In contrast, AtHB7 promotes leaf development, chlorophyll levels and photosynthesis and reduces stomatal conductance in mature plants. Moreover AtHB7 delays senescence processes in standard growth conditions.ConclusionsWe demonstrate that AtHB7 and AtHB12 have overlapping yet specific roles in several processes related to development and water stress responses. The analysis of mutant and transgenic plants indicated that the expression of AtHB7 and AtHB12 is regulated in a coordinated manner, depending on the plant developmental stage and the environmental conditions. The results suggested that AtHB7 and AtHB12 evolved divergently to fine tune processes associated with development and responses to mild water stress.

Cistrome and Epicistrome Features Shape the Regulatory DNA Landscape

“…ANAC055 is downstream of ABA and jasmonic acid signaling pathways and affects abiotic growth responses (Bu et al, 2008). HB family members play important roles in water stress and interact directly with auxin regulation (Ré et al, 2014). Three independent ChIP-seq experiments were performed on ABI5: two with an anti-ABI5 antibody in dark- and light-grown seedlings (ABI5 Ab etiolated and light) and one with an anti-GFP antibody in light grown seedlings containing a recombineered YPET-tagged ABI5 fusion protein (ABI5 YPET light).…”

Transcriptional Responses in Root and Leaf of Prunus persica under Drought Stress Using RNA Sequencing

“…Similarly, HD-ZIP and MYB TFs were strongly induced during drought, shedding light on their putative roles as mediators of drought signaling (Chew et al, 2013; Chen et al, 2014). In particular, the gene encoding transcript GF677_6534 is a putative ortholog of the ABA-dependent AtHB12 (a HD-Zip gene, which was validated by RT-qPCR) found in A. thaliana , which promotes root elongation during mild drought stress (Ré et al, 2014). Thus, after considering the previously discussed “locomotion” annotation ( Figure 3 ), we hypothesize that GF677_6534 may control primary root elongation during conditions of drought.…”

Cistrome and Epicistrome Features Shape the Regulatory DNA Landscape

“…ANAC055 is downstream of ABA and jasmonic acid signaling pathways and affects abiotic growth responses (Bu et al, 2008). HB family members play important roles in water stress and interact directly with auxin regulation (Ré et al, 2014). Three independent ChIP-seq experiments were performed on ABI5: two with an anti-ABI5 antibody in dark-and lightgrown seedlings (ABI5 Ab etiolated and light) and one with an anti-GFP antibody in light grown seedlings containing a recombineered YPET-tagged ABI5 fusion protein (ABI5 YPET light).…”