Wageningen UR Plant Breeding, Wageningen University and Research Center, Droevendaalsesteeg 1, 6708PB Wageningen, The Netherlands.
Mol Plant Microbe Interact. 2011 Apr;24(4):441-50. doi: 10.1094/MPMI-06-10-0145.
On the short arm of tomato chromosome 6, a cluster of disease resistance (R) genes have evolved harboring the Mi-1 and Cf genes. The Mi-1 gene confers resistance to root-knot nematodes, aphids, and whiteflies. Previously, we mapped two genes, Ol-4 and Ol-6, for resistance to tomato powdery mildew in this cluster. The aim of this study was to investigate whether Ol-4 and Ol-6 are homologues of the R genes located in this cluster. We show that near-isogenic lines (NIL) harboring Ol-4 (NIL-Ol-4) and Ol-6 (NIL-Ol-6) are also resistant to nematodes and aphids. Genetically, the resistance to nematodes cosegregates with Ol-4 and Ol-6, which are further fine-mapped to the Mi-1 cluster. We provide evidence that the composition of Mi-1 homologues in NIL-Ol-4 and NIL-Ol-6 is different from other nematode-resistant tomato lines, Motelle and VFNT, harboring the Mi-1 gene. Furthermore, we demonstrate that the resistance to both nematodes and tomato powdery mildew in these two NIL is governed by linked (if not the same) Mi-1 homologues in the Mi-1 gene cluster. Finally, we discuss how Solanum crops exploit Mi-1 homologues to defend themselves against distinct pathogens.
在番茄染色体 6 的短臂上，一簇抗病（R）基因进化出了 Mi-1 和 Cf 基因。Mi-1 基因赋予根结线虫、蚜虫和粉虱的抗性。此前，我们在这个簇中定位了两个基因 Ol-4 和 Ol-6，用于抗番茄白粉病。本研究旨在研究 Ol-4 和 Ol-6 是否为该簇中 R 基因的同源物。我们表明，携带 Ol-4（NIL-Ol-4）和 Ol-6（NIL-Ol-6）的近等基因系（NIL）也对线虫和蚜虫具有抗性。遗传上，对线虫的抗性与 Ol-4 和 Ol-6 共分离，这两个基因进一步被精细定位到 Mi-1 簇中。我们提供的证据表明，NIL-Ol-4 和 NIL-Ol-6 中 Mi-1 同源物的组成与其他具有 Mi-1 基因的抗线虫番茄品系 Motelle 和 VFNT 不同。此外，我们证明，这两个 NIL 对线虫和番茄白粉病的抗性均由 Mi-1 基因簇中连锁（如果不是相同）的 Mi-1 同源物控制。最后，我们讨论了茄属作物如何利用 Mi-1 同源物来抵御不同的病原体。
