Impairment of chloroplast movement reduces growth and delays reproduction of Arabidopsis thaliana in natural and controlled conditions

Abstract

The importance of chloroplast movement for plant growth in constant, controlled light and of nonphotochemical quenching (NPQ) in variable, natural light are known. Here we concurrently investigated growth and reproduction of several Arabidopsis thaliana mutants to assess the relative importance of photoprotection via chloroplast movement and NPQ. METHODS: Plants were grown outdoors (natural conditions) or in a growth chamber with variable light and chilling temperatures (controlled conditions). Phenotypic growth and reproductive variables were determined at set times before maturity in wild-type (WT) and phot1, phot2, phot1phot2 (e.g., impaired chloroplast movement, stomatal conductance, leaf flattening), chup1 (impaired chloroplast movement), and npq1 (reduced NPQ) plants. RESULTS: Mutants were most adversely affected in natural conditions, with phot1phot2 and chup1 most severely impacted. These mutants bolted later and produced fewer leaves and siliques, less leaf biomass, and fewer secondary inflorescences than WT. In controlled conditions, leaf traits of these mutants were unaffected, but phot1phot2 bolted later and produced fewer secondary inflorescences and siliques than WT. For most variables, there were significant interactions between growth conditions and plant genotype. Many variables were correlated, but those relationships changed with growth conditions and genotype. CONCLUSIONS: Phenotypic variables at the time of the harvest were strongly affected by growth conditions and genotype. In natural conditions, phot1phot2 and chup1 mutants were most adversely affected, demonstrating the importance of chloroplast movement. In controlled conditions, only phot1phot2 was consistently affected, also emphasizing the important, pleiotropic effects of phototropins. In both conditions, NPQ was less important.

Parental pericentromeric methylation status drives methylome remodelling and heterosis in epigenetic hybrids

“…DHAD is involved in salt stress response, with loss of function mutants showing increased sensitivity to abiotic stressors and reduced root growth (Zhang et al, 2015). CHUP1 is crucial for chloroplast movement in leaves in response to light (Oikawa et al, 2003) and impaired of chloroplast movement strongly affects vegetable and reproduction growth (Howard et al, 2020). Interestingly, the QTL epi on chr3 also mapped close to the QTL epi identified by Lauss et al (2017), which was associated with leaf area and flowering time in their smaller pilot study.…”

Mapping parental DMRs predictive of local and distal methylome remodeling in epigenetic F1 hybrids

“…DHAD is involved in salt stress response, with loss-of-function mutants showing increased sensitivity to abiotic stressors and reduced root ( Zhang et al, 2015 ). CHUP1 is crucial for chloroplast movement in leaves in response to light ( Oikawa et al, 2003 ) and impaired of chloroplast movement strongly affects vegetable and reproduction growth ( Howard et al, 2020 ). Among the candidate genes associated with the QTL epi on chr 2, we identified the histone methyltransferase SU(VAR)3-9 RELATED 5 (SUVR5) ( Fig S11 ).…”