[学术文献] Auxin response factor 6A regulates photosynthesis, sugar accumulation, and fruit development in tomato 进入全文
Auxin response factors (ARFs) are involved in auxin-mediated transcriptional regulation in plants. In this study, we performed functional characterization of SlARF6A in tomato. SlARF6A is located in the nucleus and exhibits transcriptional activator activity. Overexpression of SlARF6A increased chlorophyll contents in the fruits and leaves of tomato plants, whereas downregulation of SlARF6A decreased chlorophyll contents compared with those of wild-type (WT) plants. Analysis of chloroplasts using transmission electron microscopy indicated increased sizes of chloroplasts in SlARF6A-overexpressing plants and decreased numbers of chloroplasts in SlARF6A-downregulated plants. Overexpression of SlARF6A increased the photosynthesis rate and accumulation of starch and soluble sugars, whereas knockdown of SlARF6A resulted in opposite phenotypes in tomato leaves and fruits. RNA-sequence analysis showed that regulation of SlARF6A expression altered the expression of genes involved in chlorophyll metabolism, photosynthesis and sugar metabolism. SlARF6A directly bound to the promoters of SlGLK1, CAB, and RbcS genes and positively regulated the expression of these genes. Overexpression of SlARF6A also inhibited fruit ripening and ethylene production, whereas downregulation of SlARF6A increased fruit ripening and ethylene production. SlARF6A directly bound to the SAMS1 promoter and negatively regulated SAMS1 expression. Taken together, these results expand our understanding of ARFs with regard to photosynthesis, sugar accumulation and fruit development and provide a potential target for genetic engineering to improve fruit nutrition in horticulture crops.
[学术文献] Tissue-specific respiratory burst oxidase homologue -dependent H2O2 signaling to the plasma membrane H+-ATPase confers potassium uptake and salinity tolerance in Cucurbitaceae 进入全文
Journal of Experimental Botany
Potassium (K+) is a critical determinant of salinity tolerance, and H2O2 has been recognised as an important signaling molecule that mediates many physiological responses. However, the details on how H2O2 signaling regulates potassium uptake in the root under salt stress remain elusive. In this study, the salt sensitive cucumber and salt tolerant pumpkin which belong to the same family cucurbitaceae were used to answer the above question. We show that higher salt tolerance in pumpkin was related to its superior ability for K+ uptake and higher H2O2 accumulation in the root apex. Transcriptome analysis showed that salinity induced 5886 (3005 up and 2811 down) and 4679 (3965 up and 714 down) differentially expressed genes (DEGs) in cucumber and pumpkin, respectively. DEGs encoding NADPH oxidase (RBOHD), 14-3-3 protein (GRF12), plasma membrane H+- ATPase (AHA1) and potassium transporter (HAK5) showed higher expression in pumpkin than cucumber under salinity stress. Treatment with a NADPH oxidase inhibitor diphenylene iodonium resulted in a lower RBOHD, GRF12, AHA1 and HAK5 expression, reduced plasma membrane H+- ATPase activity, and smaller K+ uptake, resulting in a loss of salinity tolerance trait in pumpkin. The opposite results were obtained when the plants were pre-treated with exogenous H2O2. Knocking out of RBOHD in pumpkin by CRISPR-Cas9 editing of coding sequences resulted in lower root apex H2O2 and K+ content and GRF12, AHA1 and HAK5 expression, ultimately resulting in a salt-sensitive phenotype. However, ectopic expression of pumpkin RBOHD in Arabidopsis led to the opposite effect. Taken together, this study shows that RBOHD- dependent H2O2 signaling in the root apex is important for the pumpkin salt tolerance and suggests a novel mechanism that confers this trait, namely RBOHD-mediated transcriptional and post-translational activation of plasma membrane H+-ATPase operating upstream of HAK5 K+ uptake transporters.
Trends in Plant Science
Structural and biological evidence suggests that ABA receptor complexes operate at basal, nonstress ABA levels. Basal ABA balances primary metabolism and leaf growth in arabidopsis. Low levels of ABA play opposite roles in different tissues, inhibitory effects on leaf emergence, and promotion of root growth. Basal ABA levels support plant growth and development via a beneficial effect on plants’ water status, which comprises proper adjustment of stomatal aperture, stimulation of tissue hydraulic conductivity, and a positive regulatory role in xylem development.