Department of Plant Biotechnology, Centre for Plant Molecular Biology and Biotechnology, Tamil Nadu Agricultural University, 641 003, Coimbatore, India.
Sci Rep. 2018 Oct 24;8(1):15713. doi: 10.1038/s41598-018-34053-y.
This study was aimed at unravelling the molecular basis of root growth behavior in a drought-tolerant upland rice genotype, Nootripathu. Root tips of Nootripathu were found to possess shorter root caps and a greater number of dividing cells, favoring faster elongation compared to shallow-rooted IR20. Width and length of cortical cells in the roots of rapidly growing Nootripathu were found to be two to three times higher than IR20. Evaluation of shallow-rooted IR20, deep-rooted Nootripathu and their Recombinant Inbred Lines (RILs) for root characteristics revealed the presence of genetic variation for root traits among RILs. 2D-PAGE analysis of proteins in roots of IR20, Nootripathu and bulks of extreme RILs differing in root traits resulted in the identification of proteins co-segregating with root growth behavior and co-localized with QTLs for root traits. A putative candidate gene, OsARD4, encoding an "acireductone dioxygenase" was validated for its role in modulating the root growth pattern through genetic transformation. Transgenic ASD16 rice plants engineered for the overexpression of OsARD4 exhibited root growth characteristics similar to those of Nootripathu, including faster radical emergence, more rapid elongation of primary roots, early initiation of crown/lateral roots, and higher root biomass than the non-transgenic plants.
本研究旨在揭示耐旱性高地稻基因型 Nootripathu 根系生长行为的分子基础。研究发现，与浅根 IR20 相比，Nootripathu 的根尖端具有更短的根冠和更多的分裂细胞，有利于更快的伸长。快速生长的 Nootripathu 根的皮层细胞的宽度和长度比 IR20 高出两到三倍。对浅根 IR20、深根 Nootripathu 及其重组自交系（RIL）进行根系特征评估表明，RIL 之间存在根系特征的遗传变异。IR20、Nootripathu 和根系性状极端 RIL 混合物根蛋白的 2D-PAGE 分析导致与根系生长行为共分离并与根系性状 QTL 共定位的蛋白质的鉴定。对编码“acireductone dioxygenase”的假定候选基因 OsARD4 的功能验证表明，它通过遗传转化在调节根系生长模式方面发挥作用。过表达 OsARD4 的转基因 ASD16 水稻植物表现出与 Nootripathu 相似的根系生长特征，包括更快的根端出现、主根更快速的伸长、冠/侧根的早期起始以及比非转基因植物更高的根生物量。
