Arabidopsis Ca2+-ATPases 1, 2, and 7 in the endoplasmic reticulum contribute to growth and pollen fitness
Arabidopsis Ca2+-ATPases 1, 2, and 7 in the endoplasmic reticulum contribute to growth and pollen fitness
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DOI：
10.1093/plphys/kiab021
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发表时间：
2021-01-28
期刊：
影响因子：
7.4
通讯作者：
Harper, Jeffrey F.
中科院分区：
文献类型：
--
作者：
Ishka, Maryam Rahmati;Brown, Elizabeth;Harper, Jeffrey F.
产生细胞Ca 2+信号需要来自Ca 2+流入和流出途径的协调转运活动。在拟南芥（Arabidopsis thaliana）中，存在多种外排途径，其中一些涉及属于自抑制的Ca 2 +-ATP酶（ACA）家族的Ca 2 +-泵。在这里，我们表明，ACA 1，2和7定位于内质网（ER），是重要的植物生长和花粉育性。虽然表型的植物窝藏单基因敲除（科斯）是弱的或未检测到的，aca 1/2/7的三重KO显示花粉传递效率降低2.6倍，而通过雌配子的遗传是正常的。三重KO还导致较小的roximab，显示出高频率的病变。营养和生殖表型被拯救的转基因编码要么ACA 1，2，或7，这表明所有三个异构体是生化冗余。通过表达编码NahG（一种降解水杨酸（SA）的酶）的转基因抑制病变。三重KO突变体显示两个SA诱导标记基因，致病相关1（PR 1）和PR 2的mRNA表达升高。aca 1/2/7病变表型相似，但严重程度低于与空泡泵aca 4和11的双KO相关的SA依赖性病变。由蓝光或病原体激发子flg 22引发的Ca 2+动力学成像显示aca 1/2/7突变体显示Ca 2+瞬变，其幅度和持续时间增加。总之，这些结果表明ER定位的ACA在调节Ca 2+信号中起重要作用，并且这些泵的损失导致雄性生育力和营养生长缺陷。
Generating cellular Ca2+ signals requires coordinated transport activities from both Ca2+ influx and efflux pathways. In Arabidopsis (Arabidopsis thaliana), multiple efflux pathways exist, some of which involve Ca2+-pumps belonging to the Autoinhibited Ca2+-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 Ca2+ dynamics triggered by blue light or the pathogen elicitor flg22 revealed that aca1/2/7 mutants display Ca2+ transients with increased magnitudes and durations. Together, these results indicate that ER-localized ACAs play important roles in regulating Ca2+ signals, and that the loss of these pumps results in male fertility and vegetative growth deficiencies.