Fine root capture and phenotypic analysis for tomato infected with Meloidogyne incognita

Nematode Meloidogyne incognita is a damaging herbivore that retards root development, shoot growth and plant production. Meloidogyne incognita parasitizes in plant roots and soil, which makes observation and prediction of infection hard to implement, and always observed in the late stage or in the most serious infecting conditions. In this study, adaptive minirhizotrons (microrhizotrons) were used to observe root traits subjected to nematode Meloidogyne incognita in soil-based environment. Microrhizotrons were preset to observe roots in situ, and root images were transferred and processed to extract root diameter and root hair changes. Root system architecture was quantified and reconstructed with 3D architecture digitizer. The result showed that root began to swell since 25 days after infection. Root hair length in swelling parts was observed elongation in 20 days. The defense mechanism was not only limited to root-knot point, but also to non-knot parts in the nematodes inoculation roots. Lateral roots developed more uniformly into deeper than 100 cm in control group, but in infected group lateral roots gathered and clustered with large root angles in shallow soil layer less than 10 cm. Shoot height and injury was visually obviously after about 40 days after infection. The result indicated that microrhizotron provided a method of micro root traits tracing in situ, and root development observed by microrhizotron could give early estimation of nematodes infection than shoot development.