DEVELOPMENT AND IMPLEMENTATION OF METHODOLOGIES FOR THE
PRODUCTION OF CLEAN, ROOT ROT TOLERANT AVOCADO PLANTS
CLEAN
A. Mejía Jiménez1, J.P. Villamizar1, M.L. Orozco1,2, A. Arenas1, E. Alvarez1, M. Rodríguez2,
B. J. Orozco2, J.A. Carmona3, D. Rios3, J. Jaramillo2 and A. González1
(1)Centro Internacional de Agricultura Tropical CIAT, A.A 6713, Cali, Colombia; (2)Corporación Colombiana de
CIAT A A 6713 Cali
Investigación Agropecuaria (CORPOICA), Palmira, Colombia; (3) Profrutales LTDA, Candelaria-Valle, Colombia
Introduction
I t d ti Outputs of this project: A FIG. 1 Collection of
avocado accessions.
Phytophthora cinnamomi, the agent
cinnamomi, Fig. 1A. Identification of
• The nurse seed-etiolation-double-grafting
seed-etiolation-double- “escape trees” growing
responsible for root rot, is the most
rot, methodology (Frohlich and Platt 1971; Brokaw
(Frohlich vigorously on plantations
limiting disease in avocado (Persea 1976) was adapted and implemented in local
devastated by root rot,
as a source of tolerant
americana)
americana) around the world.
world. nurseries.
i avocado clones; Figs.
Colombia’s avocado industry is • 254 accessions of local avocado germplasm
1B, C, E, F, G, H, J, K,
and L variability of fruit
developing, but faces the challenge of were collected and sub-set tested against local
sub- B C D forms and shapes of
dealing with under-developed
under- strains of P. cinnamomi.
cinnamomi. some of the 254
avocado accessions
technologies and practices that • Collected germplasm represents a wide range of collected in 16
resulted in thousands of hectares altitudinal conditions (5 to 2183 m.a.s.l)
m.a.s.l
m a s l)
l) E F
Colombian departments
between, 5 and 2183
affected by the disease. • 30 accessions were collected as escapes from P. H I m.a.s.l.; Figs. 1D tree
cinnamomi infested soils. G trunk circumference (3.4
Tolerant Rootstocks must be used to • 21 nurseries trained on methodologies for clonal
m) of one of the
J collected trees.
protect large investments in avocado and pathogen free propagation of rootstocks. L
K
farms. • A new methodological approach t t t avocado
th d l i l h to test d
Some facts: germplasm produced reliable information.
• Collected material was incorporated into the
• P. cinnamomi cause losses of 30-50% (Tamayo
30- Colombian Avocado Germplasm Bank in Fig. 2 Isolation and characterization of the pathogen causing root
2007) in commercial nurseries. Corpoica-
Corpoica-Palmira rot of avocado in Colombia. Fig. 2A, root samples were taken from
dying root rot suspected trees in 9 Colombian departments; isolation
• The most eco-efficient strategy to alleviate
eco- • Basic and inexpensive tissue culture techniques and characterization of the pathogen morphologically (Fig. 2B) and
the problem is the use of tolerant rootstocks were used to produce clean avocado mother molecularly through ITS amplification and restriction (Drehnt et al. 2006;
(Drehnt
• Root rot tolerant rootstocks have been plants for clonal propagation FIG 2C); Fig. 2D, study of the pathogenicity of the P. cinnamomi
isolates through innoculation of Hass; Fig. 2E, places from where P.
developed for temperate but not for tropical • PCR analysis with Phytophthora specific primers cinnamomi isolates were obtained
climates (Drenth et al. 2006) showed that disinfested Bolívar Cesar
• Root rot to e a t rootstocks must be p opagated
oot ot tolerant ootstoc s ust propagated microshoots recovered from escapes growing in
Text
Carmen de
Bolívar
Manaur
e
A Antioquia
E
vegetatively P. cinnamomi infested soils are Phytophthora free La Ceja
Carmen de Santander
(Fig. 3J) Viboral
Nariño
Landazuri
San Vicente
Fig. 3 Development of methodologies for producing
• Inoculation of P. cinnamomi confirmed the
El Retiro
Caldas
pathogen free avocado clones. Figs. 3A, B and C, method for Anserma
disinfection of buds (microshoots) recovered from “escape
(microshoots) susceptible nature of cultivar Hass (Fig. 2D) and Quindío
Pijao Palestina
Pensilvania
trees” in root rot infested plots, with ethanol and sodium to e a t atu e of G755 and u e
tolerant nature o G 55 a d Duke 7. B Pueblo
Valle
V ll
hypochlorite under vacuum ; Fig. 3D, innitial in vitro culture Argelia Nuevo
surrounded by an antibiotic and antimycotic solution; Fig. 3E • Out of 55 Phytophthora isolates, 49 were of P. Candelaria
El Cerrito
Tolima
dentification of still contaminated microshoots; Fig. 3G,
microshoots; C Alvarado
production of new buds 4 weeks after starting in vitro culture;
cinnamomi,
cinnamomi, and 6 of two unidentified QuickTime™ and a
decompressor
are needed to see this picture. Palmira
Mariquita
Figs. 3H and I, plant recovery after grafting of disinfested Phytophthora species (see poster by Alvarez et D
Cauca
Cajibio
microshoots onto seedling rootstocks in the greenhouse; Fig. al.). Isolates were obtained from root samples of Popayán
Cauca
3J, PCR analysis with Phytophthora specific primers (Drenth et
(Drenth
al.
al 2006) showing that disinfested microshoots recovered from
dying avocado p
y g plants Control ANR-017 CAA-103 CAT-049
Popayán
Tambo
T b
“escapes trees” are Phytophthora free.
Fig. 4 Adaptation of the nurse seed-etiolation-double-grafting
seed-etiolation-double-
A B C methodology (Frohlich and Platt 1971; Brokaw 1976). Fig. 4A,
buds of the potential clonal rootstocks grafted onto “nurse seeds” Conclusions:
(Figs. 4B and C); Fig. 4D “etiolation” culture of the grafted shoots in
the darkness for improving rooting capability (Fig. 4J); Fig. I and J • Phytophthora cinnamomi is widely dispersed and
plant of a commercial cultivars (Hass) grafted on a cloned root rot represents a serious threat to plantations in Colombia
tolerant rootstock (G755) produced and planted at CIAT.
• Methodologies developed for disinfection and in vitro
A B C culture are useful for establishing clean clonal stocks
D E G
• Use of clonally propagated, root rot tolerant
rootstocks is recommended
• G755 and Duke 7, or cloned “escapes” are good
candidate rootstocks for Colombia
H I
D E F G
• The adapted methodology for production of clonal
rootstocks can be applied in a cost effective way to
produce root rot tolerant plants
Acknowledgments
This project was supported by the Colombian Ministry of Agriculture and
Rural Development (MADR) and the Fondo Nacional de Fomento
H I J Hortofrutícola (FNFH).
P. cinnamomi Negative
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