Two novel potential pathogens for soybean

Nematode diseases have a worldwide importance for several economic agricultural crops, such as soybean. Frequently, new or secondary pathogens arise as emergent diseases due to the intensified use of agricultural lands, causing extensive yield losses. Helicotylenchus dihystera (Hd) and Scutellonema brachyurus (Sb) appear as potential pathogens for soybean in Brazil, since their spread and population densities have been increased on soybean growing areas. Aiming to evaluate the quantitative distribution of Hd and Sb in soybean fields in South Brazil, a survey was conducted during the growing seasons of 2014–2015 and 2015–2016 in which 1,088 soil samples and 1,043 root samples were analyzed. Besides, two greenhouse experiments were conducted to evaluate the pathogenicity of both nematodes to soybean plants, in comparison with P. brachyurus (Pb), a known pathogen of the crop. The survey demonstrated that Pb, Hd and Sb are widely distributed in the States of Paraná, Santa Catarina and Mato Grosso do Sul. Besides, we proved that Hd and Sb multiply and cause root lesions in soybean cv. Potência, since they were found inside roots, and can be considered as potential pathogens for soybean plants.

线虫病害对大豆等多种经济农作物均具有全球性的重要经济影响。随着农用地开发强度不断提升，新发病原或次生病原常作为新兴病害出现，引发大面积产量损失。短体螺旋线虫（Helicotylenchus dihystera，简称Hd）与短盾线虫（Scutellonema brachyurus，简称Sb）在巴西被认定为大豆潜在病原，因其在大豆种植区的分布范围与种群密度均呈上升趋势。为明确巴西南部大豆田内Hd与Sb的定量分布情况，本研究于2014-2015及2015-2016两个大豆生育季开展调查，共分析1088份土壤样本与1043份根系样本。此外，本研究还设置2组温室盆栽试验，以该作物已知病原短颈短体线虫（Pratylenchus brachyurus，简称Pb）为对照，评估Hd与Sb对大豆植株的致病力。调查结果显示，Pb、Hd与Sb在巴拉那州、圣卡塔琳娜州及南马托格罗索州均广泛分布。此外，本研究证实Hd与Sb可在大豆品种‘Potência’的根系内繁殖并引发根斑症状，且二者可定殖于根系内部，因此可认定为大豆潜在致病病原。