ABSTRACT
Enset (Ensete ventricosum), is a perennial herbaceous plant belonging to the family Musaceae, along with banana and plantain. Despite wild populations occurring in eastern, central and southern Africa, it is only in Ethiopia that the crop has been domesticated, where it is culturally and agriculturally symbolic as a food security crop. Although an under-researched orphan crop, enset serves as a staple food for about 20% of the Ethiopian population, comprising more than 20 million people, demonstrating its value in the country. Similar to banana and plantain, enset is heavily affected by plant-parasitic nematodes, with recent studies indicating record levels of infection by the root lesion nematode Pratylenchus goodeyi. Enset is propagated vegetatively using suckers that are purposely initiated from the mother corm. However, while banana and plantain suckers have proven to be a key source of nematode infection and spread, knowledge on the infection levels and role of enset suckers in nematode dissemination is lacking. Given the high levels of plant-parasitic nematodes reported in previous surveys, it is therefore speculated that planting material may act as a key source of nematode dissemination. To address this lack of information, we assessed enset planting material in four key enset growing zones in Ethiopia. A total of 340 enset sucker samples were collected from farmers and markets and analyzed for the presence of nematodes. Nematodes were extracted using a modified Baermann method over a period of 48 h. The root lesion nematode P. goodeyi was present in 100% of the samples, at various levels of infection. These conclusive results show that planting material is indeed a key source of nematode infection in enset, hence measures taken to ensure clean suckers for planting will certainly mitigate nematode infection and spread. The effect of nematode infection on yield and quality on enset remains to be investigated and would be a way forward to complement the nematode/disease studies conducted so far and add valuable knowledge to the current poorly known impact of pests and diseases.
ABSTRACT
Meloidogyne hapla is one of the most damaging plant-parasitic nematodes in temperate regions. This nematode has a wide host range with more than 500 plant taxa including roses. In Ethiopia, rose production has developed over the past 10 years to the second most important export market after coffee. Considering the high damage potential of M. hapla, infestation of roses in Ethiopia with this nematode could result in major economic losses. Therefore, awareness of this nematode species is extremely important. During two surveys conducted in August 2011 and April 2012, M. hapla was detected in soil samples from six out of nine rose producing farms located in the districts of Ziway, Holleta, Sebeta, and Menagesha. At infested farms, rose plants appeared stunted and less productive and often showed symptoms of chlorosis and wilting. Identification was based on morphological and morphometrical characters of females, males, and second-stage juveniles, which were all within the range of variability known for this species (4). Shape of juvenile stylet knobs, shape of male head, and perennial pattern of the females with characteristic punctuations between the anus and tail terminus were also typical for M. hapla. The morphological identification was confirmed by sequence analysis of the D2-D3 expansion segment of the 28S rDNA gene following amplification with the primers D2A (5'-ACAAGTACCGTGAGGGAAAGTT-3') and D3B (5'-TCGGAAGGAACCAGCTACTA-3') (1). PCR products were purified and sequenced at the Macrogene sequencing facility service (Amsterdam, The Netherlands). Sequences were deposited in GenBank (KJ645427 to 33). The sequences were compared with previously published sequences in NCBI database and showed 96 to 100% sequence similarity with M. hapla accession nos. GQ130139, DQ328685, KF430798, and DQ145641. Unfortunately, comparison of sequences did not provide further information about the origin of this Ethiopian population, if it is native to Ethiopia or was imported with infected plant material. To the best of our knowledge, this is the first record of M. hapla occurring in Ethiopia. M. hapla is known as a serious pest of roses in colder climate regions. In Africa, it was previously reported from Tanzania (3) and South Africa (2). Thus, it appears that this species has now become also established in Ethiopia at higher altitudes (1,400 to 2,100 m above sea level) within the urban hinterland of Addis Ababa. References: (1) Baldwin et al. Mol. Phy. Evol. 8:248, 1887. (2) J. H. O'Bannon. Institute Agri. Res. 29, 1975. (3) E. Onkendi and L. N. Moleleki. Eur. J. Pl. Pathol. 136:1, 2013. (4) A. G. Whitehead. Trans. Zool. Soc. Lon.31:263, 1968.
