Selection of biofortified mini lettuce progenies resistant to Pectobacterium carotovorum subsp. carotovorum

ABSTRACT. Brazilian consumers are increasingly seeking unique vegetable products, such as mini lettuces. However, their production is hampered by a wide variety of pathogens, including Pectobacterium carotovorum subsp. carotovorum, which causes soft rot in lettuce. In this study, we aimed to select biofortified mini lettuce genotypes with good agronomic traits and resistance to P. carotovorum. A randomized block design consisting of 12 treatments, conducted in a field and greenhouse (Federal University of Uberlândia [UFU]), was used to select biofortified mini lettuce with good agronomic traits: SPAD index, stem and plant diameter, stem length, plant height, number of leaves, fresh weight, and bolt resistance. A completely randomized design consisting of 13 treatments was used for resistance or susceptibility testing. The bacterial suspension was inoculated and the following were assessed: disease severity, 16 days after inoculation; area under the disease progress curve, calculated separately at 4, 8, 12, and 16 days after inoculation as well as the sum of data calculated on all the assessment days; and the disease resistance class. The genotypes UFU 215#1 and UFU 215#2 had significantly high carotenoid concentrations. The genotypes UFU 66#4, UFU 215#1, and UFU 215#7 showed high bolt resistance. All genotypes were classified as resistant or moderately resistant to the P. carotovorum isolate, UFU A7.

摘要：巴西消费者对迷你生菜等特色蔬菜产品的需求日益增长。然而其生产受到多种病原菌的制约，其中包括引发生菜软腐病的胡萝卜软腐果胶杆菌胡萝卜亚种（Pectobacterium carotovorum subsp. carotovorum）。本研究旨在筛选兼具优良农艺性状与抗胡萝卜软腐果胶杆菌胡萝卜亚种能力的生物强化迷你生菜基因型。试验采用随机区组设计，设置12个处理，于乌贝兰迪亚联邦大学（Federal University of Uberlândia，以下简称UFU）的田间与温室中开展，用于筛选具备优良农艺性状的生物强化迷你生菜，测定指标涵盖SPAD指数（SPAD index）、茎粗与植株直径、茎长、株高、叶片数、鲜重及抽薹抗性。此外设置13个处理的完全随机设计开展抗病性鉴定：接种细菌悬浮液后，分别于接种后4、8、12、16天评估病情严重度，计算各时间点的病情进展曲线下面积（area under the disease progress curve）以及全部调查天数的病情进展曲线下面积总和，并划分抗病等级。结果表明，基因型UFU 215#1与UFU 215#2的类胡萝卜素浓度显著更高；基因型UFU 66#4、UFU 215#1与UFU 215#7表现出较强的抽薹抗性；所有供试基因型对胡萝卜软腐果胶杆菌胡萝卜亚种菌株UFU A7均表现为抗病或中抗。