從菸草毛狀根之型態與轉錄體探討根毛農桿菌 rol 基因之功能

Abstract

毛狀根 (hairy root) 是根毛農桿菌 (Agrobacterium rhizogenes) 感染植物後誘發生成的癌化組織，此組織被視為是最有潛力的植物次級代謝物生產工廠。文獻指出根毛農桿菌 Ri 質體上的 rol 基因群 (rolA 、 rolB 、 rolC 以及 rolD) 會影響毛狀根的生成。然而，尚未有文獻報導 rol 基因群如何影響毛狀根形態，以及這些基因影響的植物生理機能。因此，本篇研究之動機在利用形態調查及轉錄體學來比較野生型及個別 rol 基因缺陷之根毛農桿菌感染之菸草毛狀根之差異。形態調查結果顯示， rolB / rolC 根毛農桿菌缺陷株在毛狀根誘導率及外表型上與野生型有顯著差異，而 rolA / rolD 的影響不大。轉錄體分析 rolB / rolC 缺陷毛狀根與野生型毛狀根的結果顯示： RolB 蛋白質可能對於菸草毛狀根的脂質運送、細胞胺基酸相關生合成路徑、創傷反應、以及乙烯刺激反應具有正向調控功能； RolC 蛋白質則對於創傷反應、化學刺激反應、醣類代謝、以及脂質運送具有正向調控功能。上述結果揭示了 rolB / rolC 如何影響毛狀根形態，以及它們在毛狀根組織中調控的生理機能。

Hairy root is the tumorized tissue induced when Agrobacterium rhizogenes infects plants, and is considered as the most powerful plant secondary metabolites-producing system. The formation of hairy root have been known to related to four root inducing (rol) genes rolA, rolB, rolC, and rolD that lie in the transferred DNA (T-DNA) of A. rhizogenes root inducing (Ri) plasmid. However, no studies showed how these rol genes affect hairy root architecture. Also, there is no comprehensive –omics information of how plant cell is manipulated by the rol genes. Therefore, this study tried to answer these questions by morphological and transcriptomic analysis of tobacco hairy root induced by wild type and rol deletion mutant of A. rhizogenes. Morphological analysis revealed that lacking rolB and rolC cause impaired hairy root syndrome, while lacking rolA and rolD had little or no effects. Transcriptomic comparison of rolB / rolC deleted hairy roots compared with that of wild type indicate that RolB may positively regulate lipid transport, cellular amino acid derivative biosynthesis process, response to wounding, and response to ethylene stimulus. Meanwhile, the biological processes that may be positively regulated by RolC are response to wounding, response to chemical stimulus, carbohydrate metabolic process, and lipid transport. The results revealed how rolB and rolC affect hairy root morphology and what are the corresponding biological processes they manipulated.