Gene Structure and Expression of the High-affinity Nitrate Transport System in Rice Roots

Rice has a preference for uptake of ammonium over nitrate and can use ammonium-N efficiently. Consequently, transporters mediating ammonium uptake have been extensively studied, but nitrate transporters have been largely ignored. Recently, some reports have shown that rice also has high capacity to acquire nitrate from growth medium, so understanding the nitrate transport system in rice roots is very important for improving N use efficiency in rice. The present study identified four putative NRT2 and two putative NAR2 genes that encode components of the high-affinity nitrate transport system (HATS) in the rice (Oryza sativa L. subsp. japonica cv. Nipponbare) genome. OsNRT2.1 and OsNRT2.2 share an identical coding region sequence, and their deduced proteins are closely related to those from mono-cotyledonous plants. The two NAR2 proteins are closely related to those from mono-cotyledonous plants as well. However, OsNRT2.3 and OsNRT2.4 are more closely related to Arabidopsis NRT2 proteins. Relative quantitative reverse transcription-polymerase chain reaction analysis showed that all of the six genes were rapidly upregulated and then downregulated in the roots of N-starved rice plants after they were re-supplied with 0.2 mM nitrate, but the response to nitrate differed among gene members. The results from phylogenetic tree, gene structure and expression analysis implied the divergent roles for the individual members of the rice NRT2 and NAR2 families. High-affinity nitrate influx rates associated with nitrate induction in rice roots were investigated and were found to be regulated by external pH. Compared with the nitrate influx rates at pH 6.5, alkaline pH (pH 8.0) inhibited nitrate influx, and acidic pH (pH 5.0) enhanced the nitrate influx in 1 h nitrate induced roots, but did not significantly affect that in 4 to 8 h nitrate induced roots.

Mapping Quantitative Trait Loci for Post-Anthesis Dry Matter Accumulation in Wheat

开花期以后的 Photoassimilation 为小麦(Triticumaestivum L.) 是很重要的谷物充满。现在的学习的目的是为开花期以后的干物质累积(直接存储器存取) 印射量的特点 loci (QTL ) 。一套 120 根加倍的单倍体(DH ) 线，源于冬小麦变化 Hanxuan 10 和 Lumai 14，在北京在 2002-2004 期间在二连续生长期在地条件下面被种。开花期以后的直接存储器存取每灰煤杆和相关特点，包括旗帜叶，新鲜(FLG ) 和旗帜长叶重量(FLW；每旗帜叶弄干重量) 每耳朵(GWE ) 在开花，和粒重被调查。所有特点在两试用在 DH 人口连续地分离了。直接存储器存取显著地并且断然与 GWE 被相关，是的 withthecorrelation 系数 0.79 和 0.66 在 2002-2003 和 2003-2004 生长期(两 P【 0.01 ) ，在谷物充满建议直接存储器存取的重要性。进一步的相关分析显示出那 FLW 更密切在两生长期与直接存储器存取和 GWE thanFLG 被相关，显示那 FLW 是比在影响直接存储器存取和 GWE 的 FLG 更重要的。总共，为这四个特点的 30 QTL 在 10 上被印射并且散布染色体。Phenotypic 变化由一个个人解释 QTL 分别地为 FLG， FLW，直接存储器存取，和 GWE 在范围 5.8%-21.3% ， 5.9%-17.2% ， 5.1%-18.1% ，和 5.6%-16.2% 。为直接存储器存取的八 QTL 被检测，哪个四(在染色体 arms2AS， 4BL， 5AS，和 7AS 上) 为 GWE 与 QTL 被连接；二(在染色体手臂 5BL 和 7BL 上) 为 FLW 与 QTL 与一致。这些结果可以为直接存储器存取的改进为帮助 developingmarker 的选择提供有用信息。

Regulation of the High-Affinity Nitrate Transport System in Wheat Roots by Exogenous Abscisic Acid and Glutamine

硝酸盐是为大多数庄稼的主要的氮(N) 来源。由根房间的硝酸盐举起是氮素代谢的一个关键步骤并且广泛地在生理、分子的层次被学习了。理解硝酸盐举起怎么被调整将帮助我们与改进硝酸盐举起效率设计庄稼。现在的学习在小麦(Triticum aestivum L.) 由外长的 abscisic 酸(骆驼毛的织物) 和夫酸安(Gln ) 调查了高亲密关系的硝酸盐运输系统(帽子) 的规定根。在作为唯一的氮包含 2 mmol/L 硝酸盐的营养液种的小麦幼苗采购原料因为 2 个星期为 4 d 被剥夺 N 并且然后为 0 被转移到当面包含 50 omol/L 骆驼毛的织物，和 1 mmol/L Gln 的营养液或 2 mmol/L 硝酸盐的缺席， 0.5 ， 1 ， 2 ， 4 ，和 8 h 。对待的小麦植物然后被划分成二个组。一个组植物被用来调查在通过半量的 RT-PCR 的根的 NRT2 和 NAR2 基因接近的帽子部件的信使 rna 层次，并且其它植物设定被用来在包含 0.2 mmol/L 的营养液测量高亲密关系的硝酸盐流入率标记 p#eN 的硝酸盐。结果证明当硝酸盐不是在营养液的现在，但是进一步没由硝酸盐提高这些基因的正式就职时，那件外长的骆驼毛的织物在根导致了 TaNRT2.1， TaNRT2.2， TaNRT2.3， TaNAR2.1，和 TaNAR2.2 基因的表示。夫酸安，当硝酸盐在生长媒介是在场的时，被显示了禁止 NRT2 基因的表示，没禁止这正式就职。当 Gln 被供应到没有硝酸盐的营养液时，在根的这五基因的表示被导致。仅仅当硝酸盐在生长媒介是在场的时，这些结果暗示由 NRT2 表示的 Gln 的抑制发生。尽管外长的骆驼毛的织物和 Gln 在小麦的根导致了帽子基因，他们没导致硝酸盐流入。