The wheat leaf delayed virescence of mutant dv4 is associated with the abnormal photosynthetic and antioxidant systems

Fine mapping of leaf delayed virescence gene dv4 in Triticum aestivum

Wheat (Triticum aestivum L.) is one of the most important crops worldwide, and its yield affects national food security. Wheat leaves are key photosynthetic organs where carbohydrates are synthesized for grain yield. Leaf colour mutants are ideal germplasm resources for molecular genetic studies of wheat chloroplast development, chlorophyll synthesis and photosynthesis. We obtained a wheat mutant delayed virescence 4 (dv4) from cultivar Guomai 301. The leaves of mutant dv4 were pale yellow at the seedling stage, golden yellow at the turning green stage, and they started to turn green at the jointing stage. Genetic analysis demonstrated that the yellow-leaf phenotype was controlled by a single recessive gene named as dv4. Gene dv4 was fine mapped in a 1.46 Mb region on chromosome 7DS by SSR and dCAPS marker assays. Three putative candidate genes were identified in this region. Because no leaf colour genes have been reported on wheat chromosome arm 7DS previously, dv4 is a novel leaf colour gene. The result facilitates map-based cloning of dv4 and provides information for the construction of a high-photosynthetic efficiency ideotype for improving wheat yield.

Potential molecular mechanism of photosynthesis regulation by PeMPK7 in poplar under para-hydroxybenzoic acid stress

Due to continuous plantation of poplar, its growth and biomass accumulation may be negatively affected by the accumulation of allelochemicals such as para-hydroxybenzoic acid (pHBA) in soil. As photosynthesis is the most fundamental process in plants, it can be negatively impacted by pHBA stress. Therefore, it is crucial to improve photosynthetic capacity under pHBA stress to facilitate poplar plant growth. The mitogen-activated protein kinase (MAPK) cascade pathway is widely involved in environmental stress responses in plants. However, the regulation mechanisms of photosynthesis-related pathways by MAPK pathway genes under pHBA stress are still unclear. In this study, through transcriptome analysis and weighted gene co-expression network analysis, we observed that PeMPK7 overexpression in poplar can regulate the expression of photosynthesis-related genes and transcription factor genes, namely, WRKY1, WRKY33, and ERF3, during the early stage of pHBA stress. In addition, PeMPK7 can improve photosynthesis in poplar under long-term pHBA stress. Moreover, yeast two-hybrid and pull-down assays confirmed the interaction between PeMPK7 and PeMKK7/10. Based on these results, a schematic diagram of the pathways involved in the regulation of photosynthesis by PeMPK7 was constructed. This study provided novel insights into the molecular mechanisms of regulation of pHBA stress via MAPK cascade pathway.