Response to zinc deficiency of two rice lines with contrasting tolerance is determined by root growth maintenance and organic acid exudation rates, and not by zinc-transporter activity
Response to zinc deficiency of two rice lines with contrasting tolerance is determined by root growth maintenance and organic acid exudation rates, and not by zinc-transporter activity
复制标题
DOI：
10.1111/j.1469-8137.2009.03177.x
复制
发表时间：
2010-01-01
期刊：
影响因子：
9.4
通讯作者：
Wissuwa, Matthias
中科院分区：
文献类型：
--
作者：
Widodo;Broadley, Martin R.;Wissuwa, Matthias
土壤缺锌严重制约水稻生产，导致水稻锌营养不良。耐锌缺乏水稻品系的鉴定表明，育种可能会克服这些限制。在田间条件下，水稻耐低锌品系RIL 46在低[Zn]（ext）条件下比其不耐的母本品系IR 74更有效地吸收Zn，并产生更多的生物量。我们测试了这是否是Zn 2+转运蛋白表达增加的结果;增加脱氧mugineic酸（DMA）或低分子量有机酸（LMWOAs）的根分泌;和/或增加根产量。在田间和控制环境条件下，RIL 46和IR 74的根系锌离子转运蛋白转录本丰度的基因型差异不大。然而，RIL 46中DMA和LMWOA的根分泌量更大，与假定的配体流出基因的根表达增加一致。RIL 46在低Zn（ext）水平下维持不定根的产生，与根特异性生长素反应基因的表达改变相关，RIL 46的缺锌耐受性很可能是由于在低Zn（ext）水平下维持根的生长，增加Zn配体的外排，以及增加Zn配体复合物的吸收，这些性状是潜在的育种目标。
Zinc (Zn)-deficient soils constrain rice (Oryza sativa) production and cause Zn malnutrition. The identification of Zn-deficiency-tolerant rice lines indicates that breeding might overcome these constraints. Here, we seek to identify processes underlying Zn-deficiency tolerance in rice at the physiological and transcriptional levels.A Zn-deficiency-tolerant line RIL46 acquires Zn more efficiently and produces more biomass than its nontolerant maternal line (IR74) at low [Zn](ext) under field conditions. We tested if this was the result of increased expression of Zn2+ transporters; increased root exudation of deoxymugineic acid (DMA) or low-molecular-weight organic acids (LMWOAs); and/or increased root production. Experiments were performed in field and controlled environment conditions.There was little genotypic variation in transcript abundance of Zn-responsive root Zn2+-transporters between the RIL46 and IR74. However, root exudation of DMA and LMWOA was greater in RIL46, coinciding with increased root expression of putative ligand-efflux genes. Adventitious root production was maintained in RIL46 at low [Zn](ext), correlating with altered expression of root-specific auxin-responsive genes.Zinc-deficiency tolerance in RIL46 is most likely the result of maintenance of root growth, increased efflux of Zn ligands, and increased uptake of Zn-ligand complexes at low [Zn](ext); these traits are potential breeding targets.