Transcriptional switch for programmed cell death in pith parenchyma of sorghum stems

Abstract

Pith parenchyma cells store water in various plant organs. These cells are especially important for producing sugar and ethanol from the sugar juice of grass stems. In many plants, the death of pith parenchyma cells reduces their stem water content. Previous studies proposed that a hypothetical gene might be responsible for the death of stem pith parenchyma cells in, a promising energy grass, although its identity and molecular function are unknown. Here, we identify the gene and note that it is located on chromosome 6 in agreement with previous predictions. Sorghum varieties with a functional allele had stems enriched with dry, dead pith parenchyma cells, whereas those with each of six independent nonfunctional alleles had stems enriched with juicy, living pith parenchyma cells. expression was spatiotemporally coupled with the appearance of dead, air-filled pith parenchyma cells in sorghum stems. Among homologs that are present in flowering plants, also is required for the death of stem pith parenchyma cells. and encode previously uncharacterized NAC transcription factors and are sufficient to ectopically induce programmed death of culture cells via the activation of autolytic enzymes. Taken together, these results indicate that and its ortholog,, are master transcriptional switches that induce programmed death of stem pith parenchyma cells. Thus, targeting the gene will provide an approach to breeding crops for sugar and ethanol production.

Tissue-specific transcriptome profiling of theArabidopsis thalianainflorescence stem reveals local cellular signatures

“…Performing GO term analyses for this group of genes, identified the term 'cell death' (GO:0008219) to be enriched (Supplemental Dataset 9). This was in accordance with previous findings that programed cell death is a characteristic for pith cells (Fujimoto et al, 2018). Taken together, these analyses demonstrated that our LCM-based transcriptomes recapitulated expression profiles of characterized genes and provide informative insights into phloem cap and pith-specific cellular processes.…”

“…Supporting reliable profiling, reads from the CYTOCHROME P450 83A1 (CYP83A1) and CYP83B1 genes, which are part of the indole and aliphatic glucosinolate biosynthetic pathways and known to be expressed in the phloem cap (Nintemann et al, 2018) were significantly enriched in phloem cap samples ( Figures 5D, E). In addition, reads from the ANAC074 and AT2G38380 genes which are known to be expressed in the pith (Fujimoto et al, 2018;Schürholz et al, 2018) were enriched in pith-derived samples (Figures 5F,G).…”

Micromanagement of Developmental and Stress-Induced Senescence: The Emerging Role of MicroRNAs

“…Moreover, the TFs transiently expressed in tobacco leaf or ectopically expressed in Arabidopsis cause leaf yellowing and extensive cell death, respectively. The Sorghum bicolor orthologue of KIR1 (D) induces programmed cell death in pitch parenchyma of stalks, creating air-filled spaces [129]. The same functions of KIR1 were reported in Arabidopsis shoots.…”

“…Moreover, it is responsible for the dry stem trait in sorghum, while cultivars with juicy stalks have nonfunctional alleles of D . The KIR1 transcription factor is conserved among flowering plants and is a master transcription factor inducing programmed cell death [129]. AtORE1 is known to be post-transcriptionally regulated by microRNA164; nevertheless, the dependency of ORE1 activity on microRNA164 is not known in flower organs or inflorescence stems.…”

Modulatory Role of Reactive Oxygen Species in Root Development in Model Plant of Arabidopsis thaliana

“…Lysigenous aerenchyma contributes to the ability of plants to tolerate low-oxygen soil environments by providing an internal aeration system for the transfer of oxygen from the shoot. However, aerenchyma formation requires Programmed Cell Death (PCD) in the root cortex (Drew et al, 2000;Bartoli et al, 2015;Fujimoto et al, 2018;Guan et al, 2019). Interestingly, both the aerenchyma formation and PCD in waterlogged sunflower stems are promoted by ethylene and ROS (Steffens et al, 2011;Petrov et al, 2015;Ni et al, 2019).…”