Presentation by Dr Songbi Chen from CATAS

1. Tropical Crops Genetic Resources Institute
Chinese Academy of Tropical Agricultural Sciences
Sept. 11, 2019  Vientiane, Lao PDR
Email: songbichen@catas.cn
Breeding and Screening Activities
in China
Songbi CHEN

2. Cassava CMD-resistant breeding
Cassava virus-free culture on micro-shoot
tip in vitro and cassava viral detection
technique
CMD-tolerant cassava testing in Cambodia
Contents

3. Cassava CMD-resistant breeding
Cassava virus-free culture on micro-shoot
tip in vitro and cassava viral detection
technique
CMD-tolerant cassava testing in Cambodia
Contents

4. China –Aided the Republic of Congo Agricultural Demonstration Center (CCADC)

5. 17 cassava varieties:
Six varieties, SC5, SC8, SC9, SC10, SC6068 and SC101, from
TCGRI, CATAS, China;
4 varieties, K-265, V-130, VIOLET, NGATSA, Agricultural
Technology extension Station, Congo (Brazzaville);
3 l varieties, I144, I72, I93, from General Administration of
Agricultural Reclamation, Congo (Brazzaville);
4 l varieties, I93-0029, I93-267, I93-277, I93-144, from
Ministry of Agriculture and Animal Husbandry.
Cassava CMD-resistant breeding

6. I144 (A) I144 (B)
I93-144 (A) I93-144 (B)
Varieties with leaf incidence of cassava less than 10% after 8 months of planting
A, Uninfected cassava varieties with CMD，B, infected cassava varieties with CMD

7. Varieties with leaf incidence of cassava less than 50% after 8 months of planting
A, Uninfected cassava varieties with CMD，B, infected cassava varieties with CMD

8. Varieties with leaf incidence of cassava more than 90% after 8 months of planting
A, Uninfected cassava varieties with CMD，B, infected cassava varieties with CMD

9. Yields of different cassava varieties after 12 months of planting in
CCADC, Congo (Brazzaville)

10. Comparison of yield per plant between CMD uninfected (A)
and infected (B) cassava varieties

11. No. Varieties
Root
number/plant
Root diameter
(cm)
Root yield
(T/hr)
1 K-265 8  2.55 5.021.24 42.15  6.14
2 V-130 6  1.23 4.790.36 33.75  4.95
3 VIOLET 5  1.58 2.950.40 16.20  3.55
4 NGATSA 4  0.97 2.580.23 9.75  2.00
5 I93 7  2.23 4.190.55 25.95  1.15
6 I72 6  1.63 4.450.61 23.87  2.10
7 I144 6  1.70 4.330.45 22.32  2.23
8 I93-0029 4  0.97 4.360.37 21.14  3.90
9 I93-267 6  1.42 4.400.36 24.84  2.62
10 I93-277 4  0.82 5.240.80 23.55  3.52
11 I93-144 6  1.32 4.250.35 25.03  0.16
12 SC5 4  0.82 2.950.86 13.26  2.56
13 SC8 6  1.60 2.880.52 10.33  1.30
14 SC9 5  1.52 2.920.54 9.15  2.27
15 SC10 4  0.99 2.670.35 7.90  1.30
16 SC6068 5  1.35 2.910.26 10.90  0.36
17 SC101 6  1.62 3.920.42 22.95  0.94
Cassava root yield in CCADC, Congo (Brazzaville)

12. Training course on virus-free cassava planting Technology in Congo
(Brazzaville)

13. 2018 training course on cassava production and processing Technology
in Congo (Brazzaville)

14. Cassava CMD-resistant breeding
Cassava virus-free culture on micro-shoot
tip in vitro and cassava viral detection
technique
CMD-tolerant cassava testing in Cambodia
Contents

15. Micro-shoot tip virus-free culture in vitro.
A: Virus-free culture of the size 0.4~0.5 mm micro-shoot tip on the medium after 7
days in vitro; B: Virus-free culture of micro-shoot tip on the medium after 30 days
in vitro, 1~ 4 adventitious roots growth (as indicated by the arrows)

16. Effects of survival rate and virus-free seeding rate on the size of
SC8 micro-shoot tips
Material Shoot-tip
size (mm)
Average survival
rate (%)
Average virus-free
seeding rate (%)
SC8 0.40.5 61.7 b 35.1 a
0.61.0 90.0 a 3.3 b

17. Material Ribavirin
concentration (mg/L)
Average survival
rate (%)
Average virus-free
seeding rate (%)
SC8 0 61.7 a 35.1 b
5 61.7 a 34.8 b
10 57.7 ab 42.1 a
15 18.3c 47.2 a b
Effects of survival rate and virus-free seeding rate of SC8
micro-shoot tips on the different ribavirin concentrations

18. RT-PCR for cassava viral detection
Detection of the part of virus-free plantlets on the size 0.4~0.5 mm and
0.6~1.0 mm micro-shoot tip
Viral detection in tip
size 0.4~0.5 mm
Actin as an internal
parameter in tip size
0.4~0.5 mm
Viral detection in tip
size 0.6~1.0 mm
Actin as an internal
parameter in tip size
0.6~1.0 mm

19. Subculture of virus-free plantlet
A: Subculture of virus-free plantlet after 15 days in vitro; B:
Subculture of virus-free plantlet after 35 days in vitro

20. Virus-free I93 cassava

21. Cassava CMD-resistant breeding
Cassava virus-free culture on micro-shoot
tip in vitro and cassava viral detection
technique
CMD-tolerant cassava in Cambodia
Contents

22. Guangken (Cambodia) Agricultural Science and Technology Co LTD in
Kratie, Cambodia

23. I93 as scion to graft with CMD susceptible variety as stock
in the fields in Guangken (Cambodia) Agricultural Science
and Technology Co LTD, in Kratie, Cambodia

24. I93 as scion to graft with CMD susceptible variety as stock in the
fields in Guangken (Cambodia) Agricultural Science and Technology
Co LTD, in Kratie, Cambodia

25. I93 as scion to graft with CMD susceptible variety as stock in the
fields in Guangken (Cambodia) Agricultural Science and Technology
Co LTD, in Kratie, Cambodia