Authors: GuiDong Liu RuiDong Wang LeiChao Liu LiShu Wu CunCang Jiang
Publish Date: 2013/03/02
Volume: 370, Issue: 1-2, Pages: 555-565
Abstract
Variation in boron B efficiency in citrus in different rootstock genotypes is expressed as large differences in the occurrence of leaf symptoms and dry mass production under low B conditions but the mechanisms responsible for such differences are unknown This paper aims to determine whether differences in B uptake cellular B allocation and pectin content can explain genotype differences in B efficiency between Befficient citrange Citrus sinensis L Osb × Poncirus trifoliata L Raf and Binefficient trifoliate orange Poncirus trifoliata L Raf citrus rootstockPlants were grown hydroponically in a nutrient solution supplemented with 5 μM B for 14 days and then transferred to a Bfree medium 0 μM B or control medium 5 μM B for 35 days Boron uptake and allocation and cell wall pectin contents were examinedAfter 35 days under B deprivation shoot dry mass in trifoliate orange decreased by 28 but shoot dry mass of citrange was not significantly affected Root growth of both types of rootstock seedlings was inhibited but the trifoliate orange was affected more than the citrange In comparison with B concentrations in plants prior to the commencement of B treatments B deprivation for 35 days decreased B concentration in various parts of citrange plants and the reduction was much greater in trifoliate orange plants Trifoliate orange seedlings contained higher B concentration and total B in cell wall on a dry leaf basis than citrange subject to 5 μM B treatment However the proportion of leaf B allocated in cell wall was higher in citrange than trifoliate orange when B supply was deficient in the nutrient The changes in pectin composition in cell wall due to B deprivation differed between citrange and trifoliate orange The decreased uronic acid UA content in the Na2CO3soluble pectin was observed in both rootstock but the increased UA content in CDTAsoluble pectin was observed only in citrangeThese results demonstrated that a combination of greater B uptake ability greater B accumulation in cell walls as well as the increased CDTAsoluble pectin under limited external B supply contribute to the integrity of cell walls in citrange and therefore increased tolerance to B deficiencyWe express our great appreciation to Professor Steve McGrath of Rothamsted Research UK for his suggestions in improving this manuscript This research project was financial supported by the Chinese State Natural Science Foundation 41271320 and the Huazhong Agricultural University Scientific Technological Selfinnovation Foundation 2012YB18 2011PY150
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