Quaggiotti Silvia, Ruperti Benedetto, Pizzeghello Diego, Francioso Ornella, Tugnoli Vitaliano, Nardi Serenella
Dipartimento di Biotecnologie Agrarie, Agripolis, Università di Padova, Viale dell'Università 16, I-35020 Legnaro (Padua), Italy.
J Exp Bot. 2004 Apr;55(398):803-13. doi: 10.1093/jxb/erh085. Epub 2004 Mar 12.
In this study, a detailed characterization of earthworm low molecular size humic substances (LMS) was performed and these substances were used to study their effect on the nitrate influx in roots, tissue nitrate content, and expression of maize genes putatively involved in nitrate uptake in maize (Zea mays L.). The results show that the humic fraction with low molecular size used in this study is endowed with the characteristic structural network described for most humic substances so far isolated and confirm the presence of IAA in this fraction. The results also show that the LMS fraction of humic substances stimulates the uptake of nitrate by roots and the accumulation of the anion at the leaf level. Moreover, the analysis of the expression of genes encoding two putative maize nitrate transporters (ZmNrt2.1 and ZmNrt1.1) and of two maize H(+)-ATPase isoforms (Mha1 and Mha2) show that these substances may exert direct effects on gene transcription in roots, as shown for the Mha2 gene, and long-distance effects in shoots, as observed for the ZmNrt2.1 gene.
在本研究中，对蚯蚓低分子大小腐殖质（LMS）进行了详细表征，并利用这些物质研究它们对玉米（Zea mays L.）根系硝酸盐内流、组织硝酸盐含量以及推测参与硝酸盐吸收的玉米基因表达的影响。结果表明，本研究中使用的低分子大小腐殖质部分具有迄今为止分离出的大多数腐殖质所描述的特征性结构网络，并证实该部分存在吲哚-3-乙酸（IAA）。结果还表明，腐殖质的LMS部分刺激根系对硝酸盐的吸收以及叶片水平上阴离子的积累。此外，对编码两种推测的玉米硝酸盐转运蛋白（ZmNrt2.1和ZmNrt1.1）和两种玉米H(+)-ATPase同工型（Mha1和Mha2）的基因表达分析表明，这些物质可能对根系中的基因转录产生直接影响，如Mha2基因所示，并且对地上部产生长距离影响，如ZmNrt2.1基因所观察到的那样。
