Chin Bull Bot ›› 2018, Vol. 53 ›› Issue (5): 661-670.doi: 10.11983/CBB17141

• TECHNIQUES AND METHODS • Previous Articles     Next Articles

An Observation Method of Nodule and Root Morphology without Damage in Real-time

Zeng Yinwei, Cao Yuman, Sha Xuyang, Li Shuxia, Yang Peizhi, Hu Tianming, Liu Jinlong*()   

  1. College of Animal Science and Technology, Northwest A&F University, Yangling 712100, China
  • Received:2017-07-30 Accepted:2017-12-05 Online:2018-11-29 Published:2018-09-01
  • Contact: Liu Jinlong
  • About author:

    † These authors contributed equally to this paper


Observation of root and nodule morphology in real-time has great significance in the study of Leguminosae. However, we lack a legume plant culture system that is convenient for observing root morphology and with efficient Rhizobium inoculation and also suitable for plant growth and economical. In this work, we compared the efficacy of a paper-based Ziplock bag hydroponics method with other commonly used methods for real-time observation of nodules and root morphology of Medicago truncatula. Methods relied on quartz sand and other solid medium cultivation. M. truncatula had obstacles to observe the nodule characteristics and root morphology in real-time. Rhizobium inoculation was also inefficient with hydroponics and aeroponics, and the methods were not suitable for observing lateral root development. Moreover, we also studied the effects of melatonin on the development of root morphology of M. truncatula with the paper-based Ziplock bag hydroponics method. Although melatonin reduced the number of nodules and inhibited the lateral root elongation, the number of lateral roots and the angle of the lateral root with the main root increased. The paper-based Ziplock bag hydroponics method is a simple and effective culture method for leguminous plants, with efficient Rhizobium inoculation, which allows for observing root nodules and root morphology in real-time with non-damaged roots.

Key words: hydroponics, Medicago truncatula, melatonin, root morphology, root nodule

Figure 1

Diagram of paper-based Ziplock bag hydroponics system (right side is the picture of the actual object)(A) Seed germination; (B) Water culture seedlings; (C) Paper-based Ziplock bag hydroponics device"

Table 1

Effects of melatonin (50 μmol·mL-1) treatment on lateral root development and the inoculation of nodules in Medicago truncatula (means±SD, n=12)"

Treatment Number of nodule
per plant
Lateral root
length (cm)
Number of lateral
root per plant
Angle of lateral root
with primary root (°)
lateral root
Control 70.7±2.5 4.1±0.2 86.3±4.2 52.3±2.1 YES
Melatonin (50 μmol·mL-1) 21.3±1.5*** 1.7±0.2*** 143.3±7.1*** 85.7±3.1*** NO

Figure 2

Effects of different culture methods on inoculation of nodules and root morphology of Medicago truncatula(A)-(C) Sand culture method, (A) Sand culture device; (B) Root morphology and nodules; (C) The lost roots; (D)-(F) Hydroponics, (D) Hydroponics; (E) Root morphology; (F) The enlarged image of local roots and nodules of Figure E; (G)-(I) Aeroponics, (G) Aeroponics device; (H) Root morphology; (I) The enlarged image of local roots and nodules of Figure H; (J)-(M) Paper-based Ziplock bag hydroponics method, (J) Above-ground parts of M. truncatula (the left side is R108, the right is A17); (K) Root morphology; (L) The whole plants of M. truncatula; (M) The enlarged image of local roots and nodules of Figure L. Red arrows for the nodules, green arrows for the quartz sand; The M. truncatula is 6 weeks old except Figure J and K which is 7 weeks old."

Figure 3

Effects of different culture methods on the number of inoculated nodules in Medicago truncatula (means±SD, n=12)Different lowercase letters represent significant difference among different methods (P<0.05)."

Figure 4

The number of inoculated nodules of Medicago truncatula by hydroponics (single plant)(A) The whole plant; (B) The local roots with nodules"

Figure 5

Effects of melatonin (50 μmol·mL-1) on nodule formation and lateral root development of Medicago truncatula(A) Dynamic changes of lateral root growth; (B) The formation of nodules. * Represent significant differences at P<0.05; ** Represent highly significant differences at P<0.01; *** Represent extremely significant differences at P<0.001."

Figure 6

Effect of melatonin (50 μmol?mL–1) on the root system of Medicago truncatula (6 weeks old)(A) Control; (B) Melatonin treatment; (C) Primary root, lateral root, secondary lateral root and nodules; (D) Angle of lateral root with primary root"

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