南方根结线虫对不同砧木嫁接番茄苗活性氧清除系统的影响

采用盆栽人工接种方法,对番茄嫁接苗进行了抗性评价,研究了番茄嫁接苗叶片中抗氧化酶活性和活性氧代谢的动态变化。结果表明,接种南方根结线虫(J2)后,砧木嫁接苗表现为高抗,自根嫁接苗为高感。通过嫁接换根,与自根嫁接苗相比,砧木嫁接苗明显提高了接穗叶片的超氧化物歧化酶(SOD)、过氧化物酶(POD)、过氧化氢酶(CAT)和抗坏血酸过氧化物酶(APX)活性,降低了超氧阴离子(O.2-)产生速率以及过氧化氢(H2O2)和丙二醛(MDA)含量。表明番茄植株体内的活性氧水平和抗氧化酶活性的高低与其抗根结线虫的能力密切相关,较低的活性氧水平和较高的抗氧化酶活性有利于减轻对膜系统的伤害,提高番茄植株的抗根结线虫能力。

Effects of Meloidogyne incognita on scavenging system of reactive oxygen species in tomato seedlings grafted with different rootstocks

Root-knot nematodes (Meloidogyne spp.) have a worldwide distribution and are important endoparasitic pathogens of many plant species. In China, they are becoming one of the most serious diseases with the increase of greenhouse vegetable production. Root-knot nematode disease could inhibit growth and development, and decrease yield and quality of vegetables. The major species of root-knot nematode include M. incognita, M.hapla, M. arenaria and M. javanica. M. incognita is widely spread in Shandong province and causes a serious damage to vegetable production. Although physical and chemical approaches have been used to control the disease, they are not always effective and add the cost to tomato production. In addition, the use of chemicals causes severe environmental pollution and the residue in vegetable products may be harmful to human health. Recently, grafting cultivation using resistant rootstock could effectively prevent tomato from this disease. The effect of four resistant rootstocks on root-knot nematode disease, changes of antioxidant enzyme activities and level of reactive oxygen species (ROS) were investigated in grafted tomato seedlings, using 401, Dahong FA-2160, Fenhe518 and Bulusite as rootstocks, oumeiyuan as scion. The tomato seedlings were planted in pots and inoculated with 3000 of 2nd instars of larval M. incognita. The results showed that tomato seedlings grafted with rootstocks were highly resistant and self-rooted grafted seedlings were sensitive to M. incognita. The activities of antioxidant enzymes, such as superoxide dismutase (SOD), peroxidase (POD), catalase (CAT) and ascorbate peroxidase (APX) in leaves of scion grafted with different rootstocks were significantly increased, and the production rate of superoxide anion radical (O₂^·-), the contents of malonaldehyde (MDA) and hydrogen peroxide (H₂O₂) were reduced comparied with own-rooted grafted seedling, which suggested that the infection aggravated the extent of membrane lipid peroxidation in leaves, especially in the leaves of susceptible variety. Rootstock grafting significantly enhanced resistance of tomato seedlings to M. incognita, while the seedlings of own-rooted grafted were easily infected and formed more large nodules. Rootstock grafting increased the activities of antioxidant enzymes, decreased the level of ROS in the leaves of scion. The level of ROS and the activities of antioxidant enzymes are closely related to their ability of resistance to root-knot nematode. Low level of ROS and high activities of antioxidant enzymes were helpful for reducing the damage of root-knot nematode to membrane system and increasing resistance to root-knot nematode. It was concluded that rootstock grafting can improve resistance to M. incognita, reduce the damage of root-knot nematode infection in tomato.