Ri technology offers potential for breeding for replant disease tolerance in rose and apple

Replant disease (RD) causes severe growth and yield reduction in consecutive cultures of the same species, particularly affecting Rosaceae family members, with no sustainable management solutions currently available. This study investigated whether the root inducing (Ri) technology, which integrates bacterial rol genes into plant genomes, could enhance RD tolerance in apple and rose. Nine apple and three rose Ri genotypes were tested alongside their wildtype genotypes in a greenhouse biotest using both RD-affected and gamma-irradiated (G) RD soil. After eight weeks, all Ri genotypes displayed characteristic reduced shoot growth (21.9-75.5% in apple, 32.6-42.8% in rose) compared to wildtype genotypes in G soil. When exposed to RD conditions, some Ri genotypes showed improved tolerance in terms of RD/G ratios of growth parameters. Rose Ri genotypes exhibited a more pronounced shoot length increase during the biotest, with RD/G ratios ranging from 1.31 to 1.84, whereas the wildtype genotypes showed lower ratios of 0.90 and 0.46. One particular rose Ri genotype displayed significantly greater shoot fresh mass (0.87) and root fresh mass (1.20) ratios in comparison to its wildtype, which had notably lower ratios of 0.55 and 0.67, respectively. Likewise, two apple Ri genotypes demonstrated significantly improved shoot fresh mass ratios of 0.57 and 0.61, as well as one genotype with a significantly higher root fresh mass ratio of 1.00, while the wildtype genotype M26 showed lower ratios for shoot fresh mass (0.37) and root fresh mass (0.52). This study demonstrates for the first time that Ri technology can enhance RD tolerance in Rosaceae crops, while the underlying mechanisms remain to be investigated. These findings may pave the way for developing RD-tolerant varieties, offering a sustainable solution to a persistent problem in commercial horticulture.

连作障碍（Replant disease, RD）会导致同一物种连作栽培时出现严重的生长抑制与产量损失，尤其对蔷薇科（Rosaceae）作物危害显著，目前尚无可持续的防治方案。本研究旨在探讨将农杆菌rol基因整合至植物基因组的发根诱导（root inducing, Ri）技术，能否提升苹果与玫瑰对重茬病害的耐受性。研究采用温室生物测定法，分别使用受重茬病害侵染的土壤与γ射线辐照（gamma-irradiated, G）的重茬土壤，对9个苹果发根诱导基因型、3个玫瑰发根诱导基因型及其对应的野生型基因型进行测试。培养8周后，在γ辐照土壤中，所有发根诱导基因型的地上部生长量均较野生型基因型出现特征性下降（苹果基因型下降幅度为21.9%~75.5%，玫瑰基因型为32.6%~42.8%）。当植株处于重茬病害环境下时，部分发根诱导基因型的生长参数RD/G比值显示出更优的耐受性。玫瑰发根诱导基因型在生物测定过程中，地上部长度提升更为显著，其RD/G比值范围为1.31~1.84；而野生型基因型的对应比值仅为0.90与0.46。某一特定玫瑰发根诱导基因型的地上部鲜重比值（0.87）与根部鲜重比值（1.20）均显著高于其野生型对照，后者的对应比值仅分别为0.55与0.67。同样，2个苹果发根诱导基因型的地上部鲜重比值分别达到0.57与0.61，表现出显著提升；另有1个苹果发根诱导基因型的根部鲜重比值达1.00，同样具有显著优势。而野生型基因型M26的地上部鲜重比值（0.37）与根部鲜重比值（0.52）均处于较低水平。本研究首次证实，发根诱导技术可提升蔷薇科作物对重茬病害的耐受性，但其具体作用机制仍有待进一步探究。本研究结果可为耐重茬病害品种的培育提供思路，为商业园艺领域这一长期存在的难题提供可持续的解决方案。