Бактерии в гифосфере Phytophthora infestans и Alternaria alternata на картофеле

Фитофтороз и альтернариоз, вызываемые фитопатогенами Phytophthora infestans (Mont.) de Bary и Alternaria alternata (Fr.) Keissl., опаснейшие болезни картофеля и томата. Бактериозы картофеля другая опасная проблема как картофеля и томата, так и других с.-х. культур. Нередко возбудители бактериозов, особенно пектолитические бактерии, присутствуют на пораженных растениях вместе с фитопатогенными псевдогрибами и грибами, в том числе с Ph. infestans и A. alternata. Цель исследования оценить присутствие бактерий в гифосфере Phytophthora infestans и Alternaria alternata, а также влияние бактерий на характеристики Ph. infestans и A. alternata. Лабораторные исследования проводили в лаборатории сектора фитопатологии кафедры защиты растений в 2016-2019 годах. Использовали изоляты Ph. infestans T-9, IO-37, 161, A. alternatа Д12 из коллекций МГУ имени М. В. Ломоносова и РГАУ-МСХА имени К. А. Тимирязева. Заражение дисков клубней картофеля сортов Жуковский ранний, Ред Скарлетт, Сарпо Мира, Луговской, Удача проводили в марте 2016 года на фоне потепления погодных условий, температура в лаборатории достигала 25 С. Наличие бактерий в мицелиях исследуемых штаммов Ph. infestans, выращиваемых на овсяном агаре, проверялили посредством световой и электронной микроскопии, а также путем смывов с мицелиев и высевом на специальные питательные среды King B и YDS. В результате исследований доказано наличие пектолитических бактерий в гифосфере Ph. infestans и A. alternatа. При наличии бактерий доказаны лизис и изменения морфологии Ph. infestans и конкурентная экспрессия по локусам глюкозо-6 фосфат изомеразы (Gpi-1) и малатдегидрогеназы (Mdh-2). Инокуляция клубневых дисков четырех сортов картофеля Жуковский ранний, Ред Скарлетт, Сарпо Мира и Удача суспензиями патогенов на фоне повышенной температуры выявили значительное развитие бактериозов уже на первые сутки инкубации. Только на сорте Луговской развитие данные симптомов было в значительной степени подавлено. Мицелии Ph. infestans, A. alternata и пектолитические бактерии их гифосферы образуют на картофеле единый и достаточно стабильный патокомплекс с достаточно сложными взаимосвязями, которые предстоит изучать. Этот патокомплекс способен создать напряженный комбинированный инфекционный фон на картофеле, который в ряде случаев способен представлять для него существенную опасность.Late blight and early blight caused with phytopathogens Phytophthora infestans (Mont.) de Bary and Alternaria alternata (Fr.) Keissl. are the dangerous diseases of potato and tomato. Bacteria are connected to the other dangerous problems of both potato and tomato, and other crops. Often bacteria especially pectolytic bacteria occur on affected plants with phytopathogeneous pseudofungi and fungi with Ph. infestans и A. alternata as well. Objective of our investigation is an estimation of bacterial occurrence in Ph. infestans and A. alternata hyphosphaere as well as influence of bacteria on the Ph. infestans and A. alternate properties. Laboratory investigations were conducted at phytopathology branch of department of plant protection of RSAUMTAA in 2016-2019. Ph. infestans isolates T-9, IO-37, 161, A. alternatа isolate D12 of MSU and RSAUMTAA were investigated. Tuber disc inoculation of potato cultivars Zhukovskiy ranniy, Red Scarlett, Sarpo Mira, Lugovskoy and Udacha was done in 2016 at the temperature about 25 C. Checking bacterial occurrence was done in Ph. infestans mycelia grown at oatmeal agar by means of light and electronic microscopy as well as with transferring on special selective media King B and YDS. As a result, occurrence of pectolytic bacteria was proved to be in Ph. infestans and A. alternatа hyphosphaere. At bacterial occurrence Ph. infestans lysis and morphological deviations as well as competitive expression at the loci of Glucose 6 Phosphate Isomerase (Gpi-1) and Malate Dehydrogenase (Mdh-2) are proved to be developed. Inoculation of potato tuber discs of five cultivars Zhukovskiy ranniy, Red Scarlett, Sarpo Mira and Udacha with suspensions of pathogens at increased temperature revealed essential bacterial development at increased temperature during already first day of incubation. Manifestation of these symptoms was significantly suppressed only on cultivar Lugovskoy. Ph. infestans and A. alternata mycelia as well as pectolytic bacteria of their hyphosphaere form on potato unique and stable pathocomplex with complicated interconnections which should be studied as quickly as possible. This pathocomplex provides strong combined infective phone on potato which is able to be essentially dangerous for this crop.

Quantitative Proteomics of Potato Leaves Infected with Phytophthora infestans Provides Insights into Coordinated and Altered Protein Expression during Early and Late Disease Stages

In order to get a better understanding of protein association during Solanum tuberosum (cv. Sarpo Mira)–Phytophthora infestans incompatible interaction, we investigated the proteome dynamics of cv. Sarpo Mira, after foliar application of zoospore suspension from P. infestans isolate, at three key time-points: zero hours post inoculation (hpi) (Control), 48 hpi (EI), and 120 hpi (LI); divided into early and late disease stages by the tandem mass tagging (TMT) method. A total of 1229 differentially-expressed proteins (DEPs) were identified in cv. Sarpo Mira in a pairwise comparison of the two disease stages, including commonly shared DEPs, specific DEPs in early and late disease stages, respectively. Over 80% of the changes in protein abundance were up-regulated in the early stages of infection, whereas more DEPs (61%) were down-regulated in the later disease stage. Expression patterns, functional category, and enrichment tests highlighted significant coordination and enrichment of cell wall-associated defense response proteins during the early stage of infection. The late stage was characterized by a cellular protein modification process, membrane protein complex formation, and cell death induction. These results, together with phenotypic observations, provide further insight into the molecular mechanism of P. infestans resistance in potatos.

Virulence and Mating Type of Phytophthora infestans Isolates in the Czech Republic

To evaluate the frequency and stability of the occurrence of P. infestans races and mating types in the Czech Republic, 338 monosporic isolates were collected from 31 sites in different potato-growing areas from 2012 to 2014 and in 2016. In total, 142 isolates were evaluated for virulence and race structure using the detached leaflet assay on Black’s differential set, supplemented with cultivar Sarpo Mira and somatic hybrid REG 46F. With the exception of virulence for resistance genes R9 and Rpi-blb-1, all virulence genes were detected among isolates, with a predominance of genes R1, R3, R7, R10, and R11. Most isolates were virulent to five or more R-genes, with a mean virulence complexity of 7.1. Among the 38 races detected, the most commonly occurring races were 1.2.3.4.6.7.10.11 and 1.2.3.4.7.10.11. Of the 338 isolates tested by the pairing test and the cleaved amplified polymorphism sequence (CAPS) marker, 40% were of the A1 mating type and 60% were of the A2 mating type, with an A1 : A2 isolate ratio demonstrating the predominance of the A2 mating type each year of the survey.

Qualitative and Quantitative Late Blight Resistance in the Potato Cultivar Sarpo Mira Is Determined by the Perception of Five Distinct RXLR Effectors

Potato defends against Phytophthora infestans infection by resistance (R)-gene-based qualitative resistance as well as a quantitative field resistance. R genes are renowned to be rapidly overcome by this oomycete, and potato cultivars with a decent and durable resistance to current P. infestans populations are hardly available. However, potato cultivar Sarpo Mira has retained resistance in the field over several years. We dissected the resistance of ‘Sarpo Mira’ in a segregating population by matching the responses to P. infestans RXLR effectors with race-specific resistance to differential strains. The resistance is based on the combination of four pyramided qualitative R genes and a quantitative R gene that was associated with field resistance. The qualitative R genes include R3a, R3b, R4, and the newly identified Rpi-Smira1. The qualitative resistances matched responses to avirulence (AVR)3a, AVR3b, AVR4, and AVRSmira1 RXLR effectors and were overcome by particular P. infestans strains. The quantitative resistance was determined to be conferred by a novel gene, Rpi-Smira2. It was only detected under field conditions and was associated with responses to the RXLR effector AvrSmira2. We foresee that effector-based resistance breeding will facilitate selecting and combining qualitative and quantitative resistances that may lead to a more durable resistance to late blight.