Arabidopsis Ca2+-ATPases 1, 2, and 7 in the endoplasmic reticulum contribute to growth and pollen fitness. Issue 4 (28th January 2021)

• Record Type: Journal Article
• Authors: Rahmati Ishka, Maryam; Brown, Elizabeth; Rosenberg, Alexa; Romanowsky, Shawn; Davis, James A; Choi, Won-Gyu; Harper, Jeffrey F
• Is Part Of: Plant physiology. Volume 185:Issue 4(2021)
• Page Start: 1966
• Page End: 1985
• Publication Date: 2021-01-28
• Subjects: Plant physiology -- Periodicals; Botany -- Periodicals; Periodicals; Electronic journals; 571.2
• DOI: 10.1093/plphys/kiab021
• Languages: English
• ISSNs: 0032-0889

Abstract

Abstract: Generating cellular Ca 2+ signals requires coordinated transport activities from both Ca 2+ influx and efflux pathways. In Arabidopsis ( Arabidopsis thaliana ), multiple efflux pathways exist, some of which involve Ca 2+ -pumps belonging to the Autoinhibited Ca 2+ -ATPase (ACA) family. Here, we show that ACA1, 2, and 7 localize to the endoplasmic reticulum (ER) and are important for plant growth and pollen fertility. While phenotypes for plants harboring single-gene knockouts (KOs) were weak or undetected, a triple KO of aca1/2/7 displayed a 2.6-fold decrease in pollen transmission efficiency, whereas inheritance through female gametes was normal. The triple KO also resulted in smaller rosettes showing a high frequency of lesions. Both vegetative and reproductive phenotypes were rescued by transgenes encoding either ACA1, 2, or 7, suggesting that all three isoforms are biochemically redundant. Lesions were suppressed by expression of a transgene encoding NahG, an enzyme that degrades salicylic acid (SA). Triple KO mutants showed elevated mRNA expression for two SA-inducible marker genes, Pathogenesis-related1 (PR1 ) and PR2 . The aca1/2/7 lesion phenotype was similar but less severe than SA-dependent lesions associated with a double KO of vacuolar pumps aca4 and 11 . Imaging of Ca 2+ dynamics triggered by blue light or the pathogen elicitor flg22 revealed that aca1/2/7 mutants display Ca 2+ transients with increased magnitudes and durations. Together, these results indicate that ER-localized ACAs play important roles in regulating Ca 2+ signals, and that the loss of these pumps results in male fertility and vegetative growth deficiencies. Abstract : Autoinhibited Ca 2+ pumps in the endoplasmic reticulum make important contributions to controlling the magnitude and duration of Ca 2+ signals.