Role of pectin methylesterases in cellular calcium distribution and blossom-end rot development in tomato fruit
Role of pectin methylesterases in cellular calcium distribution and blossom-end rot development in tomato fruit
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DOI：
10.1111/j.1365-313x.2012.05034.x
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发表时间：
2012-09-01
期刊：
影响因子：
7.2
通讯作者：
Mitcham, Elizabeth J.
中科院分区：
文献类型：
--
作者：
de Freitas, Sergio T.;Handa, Avtar K.;Mitcham, Elizabeth J.
番茄果实花端腐烂病(BER)被认为是一种缺钙病害，但其发生机制尚不清楚。我们的假设是，果胶甲基酯酶(PMES)的高表达增加了结合在细胞壁上的钙离子，从而减少了可用于其他细胞功能的钙离子，从而增加了果实对BER的敏感性。本研究的目的是评价PME的表达、细胞壁上酯化果胶和钙离子结合的量对番茄果实BER发育的影响。野生型和PME沉默的番茄植株在温室中种植。盛花时，花被授粉，不再向植株提供钙离子来诱导BER。我们的结果表明，抑制PMES在番茄果实中的表达减少了结合到细胞壁的钙离子的数量，也降低了果实对BER的敏感性。野生型和PME沉默果实的总组织、细胞质和液泡钙浓度相似，但野生型果实水溶质外体Ca~(2+)含量较低，膜透性较高，这是BER的首要症状之一。我们的结果表明，质外体水溶性钙离子浓度影响果实对钙缺乏症的敏感性。
Blossom-end rot (BER) in tomato fruit (Solanum lycopersicum) is believed to be a calcium (Ca2+) deficiency disorder, but the mechanisms involved in its development are poorly understood. Our hypothesis is that high expression of pectin methylesterases (PMEs) increases Ca2+ bound to the cell wall, subsequently decreasing Ca2+ available for other cellular functions and thereby increasing fruit susceptibility to BER. The objectives of this study were to evaluate the effect of PME expression, and amount of esterified pectins and Ca2+ bound to the cell wall on BER development in tomato fruit. Wild-type and PME-silenced tomato plants were grown in a greenhouse. At full bloom, flowers were pollinated and Ca2+ was no longer provided to the plants to induce BER. Our results show that suppressing expression of PMEs in tomato fruit reduced the amount of Ca2+ bound to the cell wall, and also reduced fruit susceptibility to BER. Both the wild-type and PME-silenced fruit had similar total tissue, cytosolic and vacuolar Ca2+ concentrations, but wild-type fruit had lower water-soluble apoplastic Ca2+ content and higher membrane leakage, one of the first symptoms of BER. Our results suggest that apoplastic water-soluble Ca2+ concentration influences fruit susceptibility to Ca2+ deficiency disorders.