Tzortzakakis E A, Anastasiadis A I, Simoglou K B, Cantalapiedra-Navarrete C, Palomares-Rius J E, Castillo P
Plant Protection Institute, N.AG.RE.F., Hellenic Agricultural Organization-DEMETER, P.O. box 2228, 71003 Heraklion, Crete, Greece.
Center 'Demeter,' Hellenic Agricultural Organization - DEMETER, 5th km Drama-Thessaloniki, 66100 Drama, Greece.
Plant Dis. 2014 May;98(5):703. doi: 10.1094/PDIS-08-13-0833-PDN.
Severe plant stunting, chlorosis, and extensive root galling were observed on sunflower (Helianthus annus Pioneer Hi-bred PR64LE19, Dupont) in a commercial field at Agios Athanasios, Drama Province, northeastern Greece at the end of May 2013. Disease symptoms were observed about 1.5 months after planting, and were distributed in patches that covered approximately 2% of the whole cultivated area. Examination of the soil and root samples from selected infected plants revealed the presence of abundant root-knot nematodes. Juveniles, males, and females were extracted by sieving, decanting, and root dissection for identification using morphological traits. Nematode population densities ranging from 100 to 150 J2s per 100 cm of soil, and 150 to 3,000 eggs per g of fresh sunflower roots were observed. Identification was confirmed by perineal patterns of females and by sequencing of the D2-D3 expansion segments of 28S ribosomal RNA gene (1,3,4). All identification methods were consistent with typical Meloidogyne hispanica. Morphology of perineal patterns of females and measurements of the second-stage juveniles (J2s) matched those of the original description of M. hispanica (3). Alignment indicated that the D2-D3 sequence (GenBank Accession No. KF501128) was 99% homologous to other sequences of M. hispanica deposited in GenBank from Brazil, Portugal, and Spain (EU443606, EU443608, and GQ375158, respectively), differing in only one nucleotide. Phylogenetic analyses using maximum likelihood of this sequence placed the Meloidogyne sp. in a highly supported (100%) clade that included all M. hispanica sequences available from the GenBank database (4). Root-knot nematodes in general have been reported to cause economic losses in sunflower in Europe (2), but there are no reports of M. hispanica. M. hispanica was first found in Seville Province, southern Spain, infecting rootstocks of Prunus spp. (3). Its distribution has been confirmed worldwide on different agricultural crops. However, to our knowledge, this is the first report of M. hispanica infecting sunflower in Europe and the first report of this species on any crop for Greece. The identification of M. hispanica in sunflower is relevant because it may represent a threat for sunflower production in Greece. Research to develop sunflower varieties resistant to root-knot nematodes should now also consider M. hispanica along with other species of Meloidogyne. References: (1) K. R. Barker. Page 19 in: An Advanced Treatise on Meloidogyne. Vol. II, Methodology. K. R. Barker et al., eds. North Carolina State University Graphics, Raleigh, NC, 1985. (2) M. Di Vito et al. Nematol. Mediterr. 24:109, 1996. (3) H. Hirschmann. J. Nematol. 18:520, 1986. (4) B. B. Landa et al. Plant Dis. 92:1104, 2008.
2013年5月底，在希腊东北部德拉马省阿吉奥斯·阿萨纳西奥斯的一块商业向日葵田（先锋杂交种PR64LE19，杜邦公司）中，观察到向日葵严重矮化、黄化以及大量根部瘿瘤。病害症状在种植后约1.5个月出现，呈斑块状分布，覆盖了约2%的整个种植区域。对选定感染植株的土壤和根系样本进行检查，发现存在大量根结线虫。通过筛分、倾析和根系解剖提取幼虫、雄虫和雌虫，利用形态特征进行鉴定。观察到线虫种群密度为每100厘米土壤中有100至150条二龄幼虫，每克新鲜向日葵根中有150至3000个卵。通过雌虫会阴花纹以及28S核糖体RNA基因D2 - D3扩增片段测序（1,3,4）进行了鉴定确认。所有鉴定方法均与典型的西班牙根结线虫一致。雌虫会阴花纹形态以及二龄幼虫（J2）测量结果与西班牙根结线虫的原始描述相符（3）。序列比对表明，D2 - D3序列（GenBank登录号KF501128）与来自巴西、葡萄牙和西班牙的西班牙根结线虫在GenBank中已存序列（分别为EU443606、EU443608和GQ375158）的同源性为99%，仅相差一个核苷酸。使用最大似然法对该序列进行系统发育分析，将该根结线虫置于一个得到高度支持（100%）的分支中，该分支包含GenBank数据库中所有可用的西班牙根结线虫序列（4）。一般报道称根结线虫会在欧洲给向日葵造成经济损失（2），但尚无西班牙根结线虫的相关报道。西班牙根结线虫首次发现于西班牙南部的塞维利亚省，感染李属植物的砧木（3）。其分布已在全球不同农作物上得到确认。然而，据我们所知，这是西班牙根结线虫在欧洲感染向日葵的首次报道，也是该物种在希腊任何作物上的首次报道。在向日葵中鉴定出西班牙根结线虫具有重要意义因为它可能对希腊的向日葵生产构成威胁。现在开展培育抗根结线虫向日葵品种的研究时，除其他根结线虫物种外，也应考虑西班牙根结线虫。参考文献：(1) K. R. Barker。载于《根结线虫高级论文集》第二卷，方法学。K. R. Barker等编。北卡罗来纳州立大学图形部，罗利，北卡罗来纳州，1985年。(2) M. Di Vito等。《地中海线虫学》24:109，1996年。(3) H. Hirschmann。《线虫学杂志》18:520，1986年。(4) B. B. Landa等。《植物病害》9:1104，2008年。
