Docstoc

Genetic diversity of Mycosphaerella spp Genetic diversity of

Document Sample
Genetic diversity of Mycosphaerella spp Genetic diversity of Powered By Docstoc
					                                                                                                                     spp.
                                                                                 Genetic diversity of Mycosphaerella spp
                                                                                                    on bananas in Nigeria
                                                                                 M. Zandjanakou-Tachin1,5, I. Vroh-Bi2, P.S. Ojiambo3, A. Tenkouano4, M. Gumedzoe5, and R. Bandyopadhyay1

Introduction                                                                                                                                         Results
Bananas (Musa spp.) commonly referred to as banana and plantain,                                                                                           All the 95 Mycosphaerella isolates analyzed in this study merged into
are i      t t           ith   ld  d ti
     important crops with world production of 106 million tons per
                                            f       illi t                                                                                                    l     haplotypes (Fi 2 3A)
                                                                                                                                                           only 21 h l t       (Fig. 2, 3A).
year.                                                 diseases
year The crop is susceptible to several devastating diseases,
                                                                                                                                                           84 (88.4%) isolates grouping into 14 SNP haplotypes were identified
                             (Fig.
including Mycosphaerella (Fig 1) leaf spot diseases caused by M  M.
fijiensis, M. musicola, and M. eumusae. The disease causes severe
  j      ,             ,                                                                                                                                   as M. fijiensis (Fig. 3C), while 11 (11.6%) represented by 7 SNP
leaf necrosis and can reduce yields up to 75%. Relative prevalence                                                                                         haplotypes (Fig. 3D) were characterized as M. eumusae. M.
of Mycosphaerella species on bananas is not known in West Africa.                                                                                              i l            tf   d (Fi 3B)
                                                                                                                                                           musicola was not found (Fig. 3B).
Good diagnostic t l and understanding of the distribution and the
G d di         ti tools d d t di            f th di t ib ti     d th                                                                                       The 21 SNP haplotypes were mapped geographically (Fig. 4).
genetic diversity of the pathogen are needed to help optimize                                                                                              Several haplotypes were found in multiple sites.
                                                      cultivars
disease diagnosis and management using resistant cultivars.
                                                                                                                                                                                      g                        y
                                                                                                                                                           The two species were distinguished from each other by molecular
                                                                                                                                                           markers. Some Nigerian isolates possess unique sequence variation
                                                                                                                                                           compared to the GenBank reference checks.
Objectives
                                                                                                                                                                        g         g                                p p
                                                                                                                                                           There were significant genetic differences between most populations
         Identify d d t      i th
         Id tif and determine the
                                                                                                                                                           (P < 0.001) with an average FST of 0.126.
         distribution of Mycosphaerella
                                Musa.
         species pathogenic on Musa                                                                                                                        M eumusae displayed a higher (4.6%) intraspecific dissimilarity
                                                                                                                                                           M.                             (4 6%)
                                                                                                                                                           compared to M. fijiensis (2%).
         Investigate th genetic
         I     ti t the       ti
         structure Mycosphaerella                                                                                                                                         21 haplotypes                                            21 haplotypes
                                                                                                                                                             M                                                       M
         population isolated from                                                                                                                       bp                                                      bp
                                                                                                                                                                                                                b
                    g
         Musa in Nigeria.                                               g        y   p               p
                                                                      Figure 1. Mycosphaerella leaf spot of banana.
                                                                                                                                                                                                             500
                                                                                                                                                     500

                                                                                                                                                                                 AA                                                     B
 Materials d   th d
 M t i l and methods                                                                                                                                                           p yp
                                                                                                                                                                          21 haplotypes                                             21 haplotypes
                                                                                                                                                             M                                                       M
                                 q
         Ribosomal DNA was sequenced                                                                                                                   bp
                                                                                                                                                        p                                                       p
                                                                                                                                                                                                               bp
         and compared in 95 isolates of M.
         C
         species collected in Nigeria and                                                                                                            500
                                                                                                                                                                                                             500

           f         h k (G B k
         reference checks (GenBank
         accessions with intercontinental                                                                                                                                        C
                                                                                                                                                                                 C                                                      DD
         distribution)
         distribution).
                                                                                                                                                     Figure 3. Identification of Nigerian Mycosphaerella isolates using general PCR probe on actin and β-tubulin
                                                                                                                                                     (A),                           M.         (B), M.         (C),     M.
                                                                                                                                                     (A) and specific primers for M musicola (B) M fijiensis (C) and M eumusae (D) (D).
         Si l nucleotide polymorphism
         Single     l tid      l     hi
         (SNP) was used to identify the
         species and to determine the
         g                            p
         genetic structure of the sampled
         populations.
         Species identity was further
                        g p        p
         confirmed using species-specific
         probes for actin and β-tubulin
         gene sequences.
            p
         Populations were differentiated
         using AMOVA and FST indices
         calculated using Arlequin program
              3 11
         ver. 3.11.
         To determine the genetic                                                                                                                    Figure 4. Geographical distribution of Nigerian M. fijiensis (F) and M. eumusae (E) based on SNP haplotypes in
                                                                                                                                                      ib       l DNA. Numbers on th map are Ni i states; collection sites are indicated by black dots. Numbers
                                                                                                                                                     ribosomal DNA N b             the          Nigerian t t         ll ti    it    i di t d b bl k d t N b
         relationships and clustering                                                                                                                assigned to F and E are haplotypes and collection numbers are indicated in parentheses.
                 th Mycosphaerella
         among the M         h     ll
         isolates a distance matrix was
         isolates,                                                                                                                                   Conclusion
         generated and subsequently
         grouped by UPGMA method
         g p        y                                                                                                                                Our results suggest that M. musicola has been replaced by more frequently
         using the NTSYS program ver.                                                                                                                occurring M. fijiensis and M. eumusae against which disease management
         2.02j.                                                                                                                                         d     i t     breeding ff t h ld be directed in Ni i
                                                                                                                                                     and resistance b di efforts should b di t d i Nigeria; more
                                                                                                                                                                                       M. eumusae
                                                                                                                                                     attention should also be given to M eumusae. The work is being expanded
                                                                                                                                                     to Ivory Coast to capture a greater amount of genetic diversity of the fungi
                                                                                                                                                          est     ca
                                                                                                                                                     in West Africa.

                                                                                                                                                     R f
                                                                                                                                                     Reference
                                                                                                                                                     M. Zandjanakou-Tachin, I. Vroh-Bi, P.S. Ojiambo, A. Tenkouano, Y. M. Gumedzoe, and R. Bandyopadhyay. 2008.
                                                                                                                                                     Identification and genetic diversity of Mycosphaerella species of banana and plantain in Nigeria. Plant Pathology
                                                                                                                                                     ( press).
                                                                                                                                                     (In p     )


                                                                                                                                                     Acknowledgments
                                                                                                                                                     A k   l d    t
Figure 2 Dendogram from unweighted paired group method with arithmetic means (UPGMA)
       2.                                                                                                                                                                                                                            (TWOWS),
                                                                                                                                                     This project was supported by the Third World Organisation for Women in Science (TWOWS)
based on SNPs and Indels analysis in the ribosomal DNA.                                                                                              the Directorate General for Development Cooperation (DGDC, Belgium), and the IITA opportunity grant.


1Plant Pathology Laboratory, International Institute of Tropical Agriculture (IITA), Oyo Road, Ibadan, Nigeria; 2Central Biotechnology Laboratory,
IITA, Oyo Road, Ibadan, Nigeria; 3Department of Plant Pathology, North Carolina State University, Raleigh, NC, USA; 4Regional Center for Africa,
       y                  g          p                            gy                               y      g                  g
AVRDC-The World Vegetable Center, Duluti, Arusha, Tanzania; 5Laboratoire de Virologie et de Biotechnologie des Plantes, Université de Lomé
(Togo), Ecole Supérieure d'Agronomie, Lomé (Togo).
                                                                                                                                                                                                                                                   iit
                                                                                                                                                                                                                                               www.iita.org

				
DOCUMENT INFO
Shared By:
Categories:
Tags:
Stats:
views:40
posted:4/4/2011
language:English
pages:1