WHIRLY1 Functions in the Control of Responses to Nitrogen Deficiency But Not Aphid Infestation in Barley

Abstract

WHIRLY1 is largely targeted to plastids, where it is a major constituent of the nucleoids. To explore WHIRLY1 functions in barley (Hordeum vulgare), RNA interference-knockdown lines (W1-1, W1-7, and W1-9) that have very low levels of HvWHIRLY1 transcripts were characterized in plants grown under optimal and stress conditions. The WHIRLY1-1 (W1-1), W1-7, and W1-9 plants were phenotypically similar to the wild type but produced fewer tillers and seeds. Photosynthesis rates were similar in all lines, but W1-1, W1-7, and W1-9 leaves had significantly more chlorophyll and less sucrose than the wild type. Transcripts encoding specific subsets of chloroplast-localized proteins, such as ribosomal proteins, subunits of the RNA polymerase, and thylakoid nicotinamide adenine dinucleotide (reduced) and cytochrome b 6 /f complexes, were much more abundant in the W1-7 leaves than the wild type. Although susceptibility of aphid (Myzus persicae) infestation was similar in all lines, the WHIRLY1-deficient plants showed altered responses to nitrogen deficiency, maintaining higher photosynthetic CO 2 assimilation rates than the wild type under limiting nitrogen. Although all lines showed globally similar low nitrogen-dependent changes in transcripts and metabolites, the increased abundance of FAR-RED IMPAIRED RESPONSE1-like transcripts in nitrogen-deficient W1-7 leaves infers that WHIRLY1 has a role in communication between plastid and nuclear genes encoding photosynthetic proteins during abiotic stress.

On the move: Redox –dependent protein relocation

“…The nuclear-243 encoded WHY1 protein is targeted to chloroplasts and the nucleus, the nuclear form having 244 the same molecular mass as the processed chloroplast form. In the chloroplasts, WHY1 binds 245 to both DNA and RNA and regulates chloroplast development, plastome copy number and is 246 required for plastome gene expression, intron splicing, ribosome formation and chloroplast to 247 nucleus signaling (Comadira et al, 2015;Prikryl et al, 2008). In the nucleus, WHY1 248 functions in the transcription of senescence and defence genes as well as in the maintenance 249 of telomeres (Yoo et al, 2007) .…”

Comparative Proteomics Analysis of Coregulation of CIPK14 and WHIRLY1/3 Mediated Leaf Pale Yellowing in <em>Arabidopsis</em>

“…In barley, WHY1 RNAi knockdown mutants are shown to have more chlorophyll and less sucrose than the wild type [27]. Large numbers of genes encoding photosynthesis and protein synthesis proteins exhibit up-regulated expression in the Hvwhy1 mutants [27]. These results suggest that plastid-located WHY proteins participate in plastid-to-nucleus retrograde signaling to maintain plastid function for environmental fluctuations response.…”

“…The why1why3polIb-1 mutant shows lower photosynthetic efficiency and produces more reactive oxygen species (ROS) in chloroplast, the elevated ROS level is correlated with the intensive expression of oxidation-related nuclear genes [26]. In barley, WHY1 RNAi knockdown mutants are shown to have more chlorophyll and less sucrose than the wild type [27]. Large numbers of genes encoding photosynthesis and protein synthesis proteins exhibit up-regulated expression in the Hvwhy1 mutants [27].…”

“…Most of proteins in the third and fourth clusters show down-regulated in the why1/3-var and oeCIPK14-var lines, respectively. Among them, some of the key enzymes of Calvin cycle (spot 2, 5, 6, 14, 17, 18, 23,27,40,43,45) belong to the two branches, suggesting that the fixation rates of CO2 decrease in the why1/3-var and oeCIPK14-var variegated lines. We also find that other proteins are down-regulated in the why1/3-var and oeCIPK14-var, which are involved in light-reaction, defense and antioxidation mechanisms, amino acid metabolism, proteins metabolism and so on.Peer-reviewed version available at Int.…”

Defining biotechnological solutions for insect control in sub‐Saharan Africa

“…Moreover, herbivore‐induced resistance is likely to be constrained in plants growing on degraded soils because of JA‐linked responses to prevailing abiotic and biotic stresses (Held & Baldwin, ). Of the abiotic properties of the soils, the availability of water and essential nutrients such as nitrogen and phosphate, is the most important in determining plant growth and productivity (Comadira et al, ).…”