Zoysia japonica Chlorophyll b Reductase Gene NOL Participates in Chlorophyll Degradation and Photosynthesis

Abstract

The degradation of chlorophyll is of great significance to plant growth. The chlorophyll b reductase NOL (NYC1-like) is in charge of catalyzing the degradation of chlorophyll b and maintaining the stability of the photosystem. However, the molecular mechanisms of NOL-mediated chlorophyll degradation, senescence, and photosynthesis and its functions in other metabolic pathways remain unclear, especially in warm-season turfgrass. In this study, ZjNOL was cloned from Zoysia japonica. It is highly expressed in senescent leaves. Subcellular localization investigation showed ZjNOL is localized in the chloroplast and the bimolecular fluorescence complementation (BiFC) results proved ZjNOL interacts with ZjNYC1 in vivo. ZjNOL promoted the accumulation of abscisic acid (ABA) and carbohydrates, and the increase of SAG14 at the transcriptional level. ZjNOL simultaneously led to the excessive accumulation of reactive oxygen species (ROS), the activation of antioxidant enzymes, and the generation of oxidative stress, which in turn accelerated senescence. Chlorophyll fluorescence assay (JIP-test) analysis showed that ZjNOL inhibited photosynthetic efficiency mainly through damage to the oxygen-evolving complex. In total, these results suggest that ZjNOL promotes chlorophyll degradation and senescence and negatively affects the integrity and functionality of the photosystem. It could be a valuable candidate gene for genome editing to cultivate Z. japonica germplasm with prolonged green period and improved photosynthesis efficiency.

Comprehensive transcriptomic analysis of age-, dark-, and salt-induced senescence reveals underlying mechanisms and key regulators of leaf senescence in Zoysia japonica

“…However, Z. japonica , despite its popularity, exhibits an early yellowing phenotype in the fall ( Zhang et al., 2022 ). The shortness of its green period can be mitigated through controlling senescence ( Guan et al., 2022a ), and therefore delaying leaf senescence may be an effective means of extending the green phase of Z. japonica and thereby enhancing its economic value.…”

“…Several of these were validated as DEGs in biological samples that were independent of those used in the RNA-seq analysis ( Figures 6 , 8 ). Despite several marker genes—including ZjSGR , ZjSAG14 , and ZjNOL —being identified as general senescence markers by previous studies ( Teng et al., 2016a ; Dong et al., 2022a ; Guan et al., 2022a ), a comprehensive analysis of markers specific to responses to age-, dark-, and salt-induced senescence has been limited. Here, we identified and validated six sDEGs and fourteen cDEGs that can be used as markers for dissecting senescence-triggering factors and exploring the progression of senescence responses, respectively.…”

“…However, to date few studies have addressed leaf senescence in Z. japonica , despite the potential economic benefits of studying senescence-related phenotypes—such as visual greenness, nutritional levels, and biomass accumulation—in turfgrass ( Teng et al., 2016a ). Overexpression of ZjSGR, ZjPPH , and ZjNOL genes involved in chlorophyll degradation has been found to result in rapid leaf yellowing and/or early senescence phenotypes in Arabidopsis ( Teng et al., 2016b ; Teng et al., 2021 ; Guan et al., 2022a ). In addition, approximately 200 SAG genes were identified as potential markers of senescence via subtractive hybridization of dark-induced leaf senescence in Z. japonica ( Cheng et al., 2009 ).…”

Integration of ATAC-seq and RNA-seq Reveals the Dynamics of Chromatin Accessibility and Gene Expression in Zoysiagrass Response to Drought

“…Furthermore, drought stress has a wide-ranging effect on plant gene expression [9,10]. It increases the levels of antioxidant, dehydrin, and proline-synthesizing enzymes while decreasing the levels of genes involved in photosynthesis and chlorophyll synthesis [7,11]. In addition, drought stress can in uence gene expression patterns and non-coding RNA expression [12].…”

Integration of ATAC-seq and RNA-seq identifies novel candidate genes associated with drought tolerance inZoysia japonicaSteud

“…Furthermore, drought stress has a wide-ranging effect on plant gene expression (Bushman et al ., 2021; Xu et al ., 2013). It increases the levels of antioxidant, dehydrin, and proline-synthesizing enzymes while decreasing the levels of genes involved in photosynthesis and chlorophyll synthesis (Merewitz et al ., 2011; Guan et al ., 2022 a ). In addition, drought stress can influence gene expression patterns and non-coding RNA expression (Gelaw and Sanan-Mishra, 2021).…”