2026-07-10 弘前大学
図1.（A）X線マイクロコンピュータ断層撮影（CT）を用いて定量化した、DJ123およびNERICA4の一次根（PR）におけるL型側根（LLR）の密度
＜関連情報＞
- https://www.hirosaki-u.ac.jp/topics/115316/
- https://academic.oup.com/jxb/advance-article/doi/10.1093/jxb/erag232/8695047
量的形質遺伝子座qLDC5は、オーキシン依存的に主根の分岐を制御する Quantitative trait locus qLDC5 regulates primary root branching in an auxin-dependent manner
Lam Thi Dinh,Bipin K Pandey,Yoshiaki Ueda,Nicola Leftley,Brian S Atkinson,Malcolm J Bennett,Matthias Wissuwa
Journal of Experimental Botany Published:27 May 2026
DOI:https://doi.org/10.1093/jxb/erag232
Abstract
L-type lateral root (LLR) density determines root system architecture, affecting nutrient acquisition in rice (Oryza sativa L.), particularly under low-phosphorus conditions. Previous studies identified genotypic differences in LLR density and a quantitative trait locus (QTL) enhancing LLR density on crown roots (qLDC5). We showed that LLR densities on crown and primary roots were closely correlated and confirmed higher LLR density on primary roots in qLDC5 donor DJ123 compared with the African variety NERICA4 using X-ray micro-computed tomography. We confirmed the qLDC5 effect in a field experiment for LLR density on primary roots. LLR densities on primary and crown roots, therefore, appear under similar genetic control. Developmental analyses revealed that DJ123 and NDJ188—a derivative line harboring qLDC5—initiate more lateral root primordia than NERICA4, with a higher proportion progressing to elongation, but that exogenous auxin application reversed this ranking. Within qLDC5, auxin biosynthesis gene OsYUCCA2 and auxin response factor OsARF15 were up-regulated in DJ123. Transcriptome analysis revealed an indirect auxin-mediated regulatory network underlying LLR variation. Differentially expressed genes in DJ123 and NDJ188 were enriched for ent-kaurene and gibberellin metabolism, including the robust induction of OsGA2ox5. These findings suggest qLDC5 increases lateral root density by coordinating gibberellin, auxin, and terpene pathways.
