AGRIS - 

2024

Axel Poulet | Min Zhao | Yongyan Peng | Yongyan Peng | FangFei Tham | Mauren Jaudal | Mauren Jaudal | Lulu Zhang | Josien C. van Wolfswinkel | Joanna Putterill

Optimized flowering time is an important trait that ensures successful plant adaptation and crop productivity. SOC1-like genes encode MADS transcription factors, which are known to play important roles in flowering control in many plants. This includes the best-characterized eudicot model Arabidopsis thaliana (Arabidopsis), where SOC1 promotes flowering and functions as a floral integrator gene integrating signals from different flowering-time regulatory pathways. Medicago truncatula (Medicago) is a temperate reference legume with strong genomic and genetic resources used to study flowering pathways in legumes. Interestingly, despite responding to similar floral-inductive cues of extended cold (vernalization) followed by warm long days (VLD), such as in winter annual Arabidopsis, Medicago lacks FLC and CO which are key regulators of flowering in Arabidopsis. Unlike Arabidopsis with one SOC1 gene, multiple gene duplication events have given rise to three MtSOC1 paralogs within the Medicago genus in legumes: one Fabaceae group A SOC1 gene, MtSOC1a, and two tandemly repeated Fabaceae group B SOC1 genes, MtSOC1b and MtSOC1c. Previously, we showed that MtSOC1a has unique functions in floral promotion in Medicago. The Mtsoc1a Tnt1 retroelement insertion single mutant showed moderately delayed flowering in long- and short-day photoperiods, with and without prior vernalization, compared to the wild-type. In contrast, Mtsoc1b Tnt1 single mutants did not have altered flowering time or flower development, indicating that it was redundant in an otherwise wild-type background. Here, we describe the generation of Mtsoc1a Mtsoc1b Mtsoc1c triple mutant lines using CRISPR-Cas9 gene editing. We studied two independent triple mutant lines that segregated plants that did not flower and were bushy under floral inductive VLD. Genotyping indicated that these non-flowering plants were homozygous for the predicted strong mutant alleles of the three MtSOC1 genes. Gene expression analyses using RNA-seq and RT-qPCR indicated that these plants remained vegetative. Overall, the non-flowering triple mutants were dramatically different from the single Mtsoc1a mutant and the Arabidopsis soc1 mutant; implicating multiple MtSOC1 genes in critical overlapping roles in the transition to flowering in Medicago.

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Directory of Open Access Journals - Sweden

2023

Mingxing Tang | Haoyu Wang | Xin Qi | Teng He | Bin Zhang | Entao Wang | Miao Yu | Beinan Wang | Fang Wang | Zhongkuan Liu | Xiaoyun Liu

The double selection of environment adaptation and host specificity forced the diversification of rhizobia in nature. In the tropical region of China, Medicago polymorpha and Medicago lupulina are widely distributed, particularly in purple soil. However, the local distribution and diversity of rhizobia associated with these legumes has not been systematically investigated. To this end, root nodules of M. polymorpha and M. lupulina grown in purple soil at seven locations in Yunnan Province of China were collected for rhizobial isolation. The obtained rhizobia were characterized by RFLP of 16S–23S rRNA intergenic spacer, BOXAIR fingerprinting, and phylogeny of housekeeping and symbiosis genes. As result, a total of 91 rhizobial strains were classified into species Sinorhizobium medicae and S. meliloti, while three nodC gene types were identified among them. S. medicae containing nodC of type I was dominant in farmlands associated with M. polymorpha; while S. meliloti harboring nodC of type III was dominant in wild land nodulated by M. lupulina. For both rhizobial species, greater genetic diversity was detected in the populations isolated from their preferred host plant. A high level of genetic differentiation was observed between the two Sinorhizobium species, and gene flow was evident within the populations of the same species derived from different soil types, indicating that rhizobial evolution is likely associated with the soil features. To examine the effects of environmental features on rhizobial distribution, soil physicochemical traits and rhizobial genotypes were applied for constrained analysis of principle coordinates, which demonstrated that soil features like pH, nitrogen and sodium were the principle factors governing the rhizobial geographical distribution. Altogether, both S. medicae and S. meliloti strains could naturally nodulate with M. polymorpha and M. lupulina, but the rhizobium-legume symbiosis compatibility determined by both the host species and soil factors was also highlighted.

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Directory of Open Access Journals - Sweden

2023

Kojevnikova, A.

The article presents materials on the study of herbivorous pests of Medicago in Fergana Valley from the order Homoptera, their species composition, the most harmful species of the EuscelisBrullé genus, their food relations, biological characteristics, harmfulness, features of development phases, their natural enemies were noted. It has been determined that the Cicadellidae family occupies a special place among the Homoptera; it is ecologically associated with various biotopes and plays an important role in agrobiocenosis. As a result of the research, it was revealed that the species of Homoptera, in particular cicadas, are characterized by complex bioecological features, highly specialized and well adapted for living in Fergana Valley. The studies are of practical importance, since some species of cicadas: Euscelis lineolata Brullé, Euscelis plebeius (Fallén)are pests of Medicago. The author revealed the harmfulness of cicada species found on Medicago, which is as follows: Insects suck juices from the vascular bundles of roots, stems, leaf veins and from leaf cells. They inflict wounds on the vegetative parts of the plant with their ovipositor during oviposition. Some species transmit viral plant diseases. | В статье представлены материалы по изучению вредителей люцерны из отряда равнокрылых (Homoptera) в Ферганской долине, их видовой состав, отмечены наиболее вредоносные виды из рода Euscelis Brullé, их пищевые связи, биологические особенности, вредоносность, особенности фаз развития, их естественные враги. Определено, что среди равнокрылых, семейство Cicadellidae занимает особое место, оно экологически связано с различными биотопами и играет важную роль в агробиоценозах. В результате проведенных исследований выявлено, что виды равнокрылых насекомых, в частности цикад, в Ферганской долине характеризуется сложными биоэкологическими особенностями, высоко специализированы и хорошо приспособлены для обитания. Исследования имеют практическое значение, поскольку некоторые виды цикад: Euscelis lineolata Brullé, Euscelis plebeius (Fallén) являются вредителями люцерны.

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Publishing center Science and Practice - Russian Federation

2023

Stepanov, A.F. | Khramov, S.Yu.

The fundamental role in the feed production of the West Siberian region belongs to perennial grasses, which occupy about 40% in the structure of forage crops on arable land. In the future, in order to satisfy animal husbandry in energy-rich cheap feed, it is planned to expand the species composition of legumes and increase their share in the structure of single-species and mixed crops with cereals of up to 70%. The experimental work was carried out in 2015–2019 in the subtaiga zone of the Omsk region on the experimental field of the Omsk Agrarian Scientific Center. The experiments were laid in 2015 and again in 2016 on gray forest soil. The purpose of the work is to give a comparative assessment of perennial leguminous grasses in terms of productivity, nitrogen–fixing ability and adaptability in the conditions of the non-chernozem zone of the West Siberian region. The 'Local Tar' red clover was cultivated (the norm is 3 million germinating seeds/ha), the 'Omsk early ripeniong' yellow melilot and the 'Gornoaltaisky 87' Eastern galega (both – 4 million germinating seeds/ha), alfalfa variegated hybrid Flora 7 (6 million germinating seeds/ha). The crops were mown from the 2nd year of life once during the growing season in the flowering phase. Studies have revealed that in these conditions, the use of Eastern galega and variegated alfalfa is promising. These types of herb legumes differ from the conventionally cultivated clover in a longer period of economic use of the herbage and the timing of the onset of mowing ripeness, increased symbiotic activity (Cf = 0.72–0.76), environmental adaptability to local conditions and high productivity. The yield of the herbage of variegated alfalfa on average (for 2 experimental series) was 24.4 t/ha, Eastern galega – 25.9 t/ha, which is more than red clover by 21 and 28%, respectively. The collection of dry matter from a hectare of these herb species is at the level of 4.93–5.23 t, fodder units – 3.30–3.86 t, crude protein – 0.98–1.22 t; but the same indicators of red clover crops are only 4.08, 2.61 and 0.73 t respectively. | Основополагающая роль в кормопроизводстве Западно-Сибирского региона принадлежит многолетним травам, занимающим в структуре посева кормовых на пашне около 40%. В перспективе для удовлетворения животноводства в энергонасыщенных дешевых кормах планируется расширить видовой состав бобовых культур и довести долю их участия в структуре одновидовых и смешанных посевах со злаками до 70%. Экспериментальная работа выполнена в 2015–2019 гг. в подтаежной зоне Омской области на опытном поле Омского Аграрного научного центра. Опыты закладывали в 2015 и повторно в 2016 гг. на серой лесной почве. Цель работы – дать сравнительную оценку многолетним бобовым травам по продуктивности, азотфиксирующей способности и адаптивности в условиях нечерноземной зоны Западно-Сибирского региона. Возделывали клевер красный Тарский местный (норма 3 млн всхожих семян/га), донник желтый Омский скороспелый и козлятник восточный Горноалтайский 87(оба – 4 млн всхожих семян/га), люцерну пестрогибридную Флора 7(6 млн всхожих семян/га). Травы скашивали со 2-го года жизни один раз за вегетацию в фазе цветения. Исследованиями выявлено, что в данных условиях перспективно использование козлятника восточного и люцерны пестрогибридной. Эти виды бобовых трав отличаются от традиционно возделываемого клевера более продолжительным периодом хозяйственного использования травостоя, сроками наступления укосной спелости, повышенной симбиотической активностью (Кф = 0,72–0,76), экологической адаптивностью к местным условиям и высокой продуктивностью. Урожайность зеленой массы люцерны пестрогибридной в среднем (за 2 закладки опыта) составила 24,4 т/га, козлятника восточного – 25,9 т/га, что больше, чем у клевера лугового, на 21 и 28% соответственно. Сбор сухого вещества с гектара этих видов трав находится на уровне 4,93–5,23 т, кормовых единиц – 3,30–3,86 т, сырого протеина – 0,98–1,22 т, те же показатели посевов клевера лугового составляют лишь 4,08; 2,61 и 0,73 т.

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Central Scientific Agricultural Library - Russian Federation

2023

Bakshaev, D.Yu.

The results of yield analysis and biological efficiency of festulolium and alfalfa intercropping in the forest-steppe zone of Western Siberia are presented. Different sowing methods and nitrogen fertilizers norms were applied. The festulolium and alfalfa intercropping at different alternation of rows reduces the yield of green matter by 8.9-15.1% compared to the sole festulolium cropping. Nitrogen application at a norm of 30 kg/ha significantly increased the yield of festulolium and alfalfa mix in the variants of inter-row sowing by 21.2% and in the variant of sowing by seed mixture by 20.2% due to the increase of shoot number per one festulolium plant by 11.1%, and the shoot weight - by 12.5-17.8%. An increase in nitrogen norm to 60 kg/ha significantly increased the of festulolium yield 16.13 t/ha green matter (74.1%) compared with unfertilized background due to an increase in the number of shoots on the plant by 26.6% and an increase in weight per a shoot by 30.1%. There was a 21.0-30.2% decrease in the number of shoots of the cereal component in the mixtures and a 76.7-82.1% decrease in the number of shoots of the legume component. At the same time, the shoot weight of festulolium increased by 8.3-42.5%, while that of alfalfa decreased by 54.3-81.5%, indicating its depression. Land equivalent ratio (LER) is higher in the variants with the application of fertilizers. With no nitrogen use, the major share of the factor belongs to festulolium. With the nitrogen application in small norms, the impact of the legume component increases through increased competitive ratio (CR). At the same time, a positive value of the coefficient of aggressivity (CA) was noted in the cereal component, which characterizes it as the dominant species. | Представлены результаты анализа урожайности и биологической эффективности совместного возделывания фестулолиума и люцерны при различных способах посева и внесения азотных удобрений в условиях лесостепной зоны Западной Сибири. Совместный посев фестулолиума с люцерной при различном чередовании рядов снижает урожайность зеленой массы на 8,9–15,1% по сравнению с одновидовым посевом фестулолиума. Внесение азота в дозе 30 кг/га достоверно увеличило урожайность смесей фестулолиума с люцерной в вариантах черезрядного посева на 21,2% и в варианте посева смесью семян на 20,2% за счет увеличения количества побегов на растении фестулолиума на 11,1%, массы побега – на 12,5–17,8%. Увеличение дозы азота до 60 кг/га достоверно повысило урожайность фестулолиума на 16,13 т зеленой массы/га (74,1%) по сравнению с неудобренным фоном за счет увеличения количества побегов на растении на 26,6% и увеличения массы одного побега на 30,1%. В смесях отмечено уменьшение на 21,0–30,2% численности побегов злакового компонента и на 76,7–82,1% – бобового. У фестулолиума масса побега увеличилась на 8,3–42,5%, у люцерны – снизилась на 54,3–81,5%, что свидетельствует об ее угнетении. Показатель эффективности использования пашни (LER) отмечен выше в вариантах с внесением удобрений. Без использования азота основная доля фактора принадлежит фестулолиуму. С внесением небольших доз азота возрастает влияние бобового компонента за счет повышения конкурентоспособности (CR). При этом положительное значение коэффициента агрессивности (CA) отмечено у злакового компонента, что характеризует его как доминирующий вид.

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Central Scientific Agricultural Library - Russian Federation

2023

Timoshkin, O.A.

The issue of the formation of highly productive agrophytocenoses based on perennial grasses adapted to the conditions of the forest-steppe to provide the animal husbandry with high-quality feeds is relevant. The purpose of the research is to study the influence of seeding rates, the level of of mineral fertilizers application and the timing of harvesting alfalfa and brome in mixed crops on the collection of dry matter and the competitive ability of the components. The research was carried out at the Penza Research Institute of Agriculture in 2017-2022. The new varieties were used as the research objects, Medicago varia 'Darya' (included in the State Register for 4, 5, 7 regions of the Russian Federation), Bromus inermis 'Udalets' (included in the State Register for 5, 7 regions of the Russian Federation). The seeding rate of crops in pure cropping is 6 million germinating seeds per 1 ha, in mixed cropping – according to the experimental scheme. The sowing method is ordinary (skip-row). Sowing was carried out in the summer (in June), uncovered. Establishment of field experiments, records and analyzes were carried out in accordance with generally accepted guidelines. As a result of the research, significant differences in the collection of dry matter between the variants as to seeding rates, the levels of fertilizer application and the timing of mowing by years of use have been identified. Alfalfa at a seeding rate of 70% (of the total) was highly competitive in mixtures with brome. Reducing the seeding rate of alfalfa from 70 to 40% reduces its competitiveness while increasing the competitiveness of brome. The brome competitiveness in the years of use decreases from 0.3-6.3 in the 1st year of use to 0.2-2.2 in the 3rd year of use. The application of fertilizers contributed to the growth of the competitiveness in brome, while it decreased in alfalfa. | Актуальна проблема формирования высокопродуктивных агрофитоценозов на основе адаптированных к условиям лесостепи многолетних трав с целью обеспечения отрасли животноводства качественными кормами. Цель исследований - изучение влияния норм высева, уровня применения минеральных удобрений и сроков уборки люцерны и костреца в смешанных посевах на сбор сухого вещества и конкурентную способность компонентов травосмеси. Исследования в Пензенском НИИ сельского хозяйства в 2017-2022 гг. В качестве объектов исследований использовали новые сорта люцерны изменчивой – сорт Дарья (внесен в Госреестр по 4, 5, 7 регионам РФ) и костреца безостого – сорт Удалец (внесен в Госреестр по 5, 7 регионам РФ). Норма высева культур в чистом виде – 6 млн всхожих семян/га, в смешанных посевах – согласно схеме опыта. Способ посева – рядовой (черезрядный). Посев проводили летом (в июне), беспокровно. Закладку полевых опытов, учеты и анализы проводили в соответствии с общепринятыми методическими указаниями. В результате исследований установлены существенные различия в сборе сухого вещества между вариантами по годам пользования, по нормам высева, уровням применения удобрений и срокам скашивания. Люцерна при норме высева 70% от полной отличалась высокой конкурентоспособностью в смесях с кострецом. Снижение нормы высева люцерны с 70 до 40% снижает ее конкурентоспособность при одновременном увеличении конкурентоспособности костреца. Конкурентоспособность костреца по годам пользования снижается с 0,3-6,3 в 1-й год пользования до 0,2-2,2 в 3-й год пользования. Внесение удобрений способствовало росту конкурентоспособности костреца при ее снижении у люцерны.

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Central Scientific Agricultural Library - Russian Federation

2023

Skamarokhova, A.S. | Vlasov, A.B. | Yurin, D.A. | Svistunov, A.A. | Griguletskij, V.G.

The research aim is to study the use effect of the organic growth substance on the yield formula in alfalfa 'Bazhena' after pre-sowing seed treatment. Field experiments were carried out in the Central Chernozem Zone of the Krasnodar Territory. The new organic growth substance under testing consists of sodium salts of naphthenic (fatty) acids, rapeseed oil and water. Alfalfa hybrid 'Bazhena' (Medicago varia Martin) was sown at the seeding rate of 2 g/m2. The experimental seeds were treated with an aqueous solution of the Grivlag growth substance (GVG) at a concentration of 0.02 mL/L 24 h before sowing. Spraying seeds with a solution was carried out from a hand-hold device (spray bottle) for spraying liquids into small drops. Then the seeds were distributed as thinly as possible over the paper, covered with a dense linen cloth, and remained in this state at room temperature (19-20 deg.С) for 24 h. The seeds in the control variant were treated with pure water of the same volume using a spray bottle. Seeds were sown manually, by continuous sowing, the seeding depth was 1.5-2 cm. Experiments have shown a change in the alfalfa yield formula depending on pre-sowing seed treatment consequences: alfalfa leaf weight is increased an average by 5.02% for three mowings; the total weight of plant stems is increased by 14.12%; on the experimental plot, the flowering phase began earlier, the number of inflorescences (flowers) per a plant was more compared with the control plot. | Цель исследований - изучение влияния применения органического ростового вещества на структуру урожая после предпосевной обработки семян люцерны сорта Бажена в условиях Центральной черноземной зоны Краснодарского края. Проведены полевые опыты по исследованию влияния нового органического ростового вещества, состоящего из натриевых солей нафтеновых (жирных) кислот, рапсового масла и воды, при предпосевной обработке семян люцерны сорта Бажена. Высевалась люцерна синегибридная сорта Бажена (Medicago varia Martin). Норма высева люцерны в опыте составляла 2 г/м2, опытные семена за 24 ч до посева обрабатывали водным раствором ростового вещества Гривлаг (GVG) в концентрации 0,02 мл Гривлага на 1 л воды. Опрыскивание семян раствором проводилось из ручного прибора для распыления жидкостей на мелкие капли (пульверизатором), затем эти семена, распределенные максимально тонко по бумаге, укрывались плотной льняной тканью и оставались в таком состоянии при комнатной температуре (19-20 град. С) 24 часа. Семена в контрольном варианте обрабатывались чистой водой из пульверизатора в таком же объеме. Высевались семена вручную, сплошным севом, глубина заделки семян составляла 1,5-2 см. Опытами установлено изменение структуры урожая люцерны в зависимости от результатов предпосевной обработки семян: в среднем по трем укосам получено увеличение массы листьев люцерны на 5,02% и увеличение общей массы стеблей растений на 14,12%; на опытном участке раньше наступила фаза цветения, причем и число соцветий (цветков) у растений здесь было больше, чем на контрольном участке.

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Central Scientific Agricultural Library - Russian Federation

2023

Ostrovskij, V.A. | Kokonov, S.I. | Ryabova, T.N.

Alfalfa is important for forage production since it is nearly the only crop that increases soil fertility and can be successfully cultivated both on rain-fed and irrigated lands. The research determined the varietal features of the formation of seed productivity of variegated alfalfa varieties under the arid conditions of Northern Kazakhstan. The research was carried out in 2016-2019 in the stationary field experiments undertaken in the A.I. Barayev Research and Production Centre for Grain Farming in the Republic of Kazakhstan. The soil of the experimental site was a low-humus southern calcareous chernozem with a high content of carbonates. There were studied 32 varieties of variegated alfalfa of different ecological and geographical origin, including 10 varieties of Kazakhstan breeding, 18 varieties of Russian breeding, 3 varieties of Canadian breeding and 1 variety of Ukrainian breeding. It has been found that the varieties 'Shortandinskaya 2', 'Karagandinskaya 1', 'Karabalykskaya 18', 'Karabalykskaya raduga', 'Karabalykskaya zhemchuzhina', 'Lutsia 14', 'Kokshe', 'Lazurnaya' of Kazakhstan breeding, the varieties 'Uralochka', 'Nakhodka', 'Sarga' of Russian breeding were distinguished by the highest seed productivity of 2.31-2.48 dt/ha. Harvesting of alfalfa varieties for seeds can be started already in the first year of use, this does not reduce the density and productivity of grass stands in the subsequent years of use. The varietal reaction of variegated alfalfa used for cultivation was revealed. The seed productivity in the fourth use year relative the third one reduced in the varieties 'Muslima', 'Tatarskaya pastbishchnaya', 'Flora 7', 'Flora 4', and 'Ferax' by 20-29%, in 'Zarya', 'Guzel', 'Voronezhskaya 6', and 'Rhizoma' by 34-37%, in 'Blagodat' and 'Nadezhda' by 40-44%, 'Rangelander' by 50%. These data indicate the inexpediency of using 4th use grass stands for seeds. | Люцерна важна для кормопроизводства, так как это едва ли не единственная культура, повышающая плодородие почвы и успешно выращиваемая как на богарных, так и на орошаемых землях. В ходе исследования - определяли сортовые особенности формирования семенной продуктивности сортов люцерны изменчивой в аридных условиях Северного Казахстана. Исследования проводили в 2016-2019 гг. на базе стационарных полевых опытов, заложенных в Научно-производственном центре зернового хозяйства им. А. И. Бараева Республики Казахстан. Почва опытного участка – малогумусный южный карбонатный чернозем с высоким содержанием карбонатов. Изучали 32 сорта люцерны изменчивой разного эколого-географического происхождения, в том числе 10 сортов казахстанской селекции, 18 сортов российской селекции, 3 сорта канадской селекции и 1 сорт – украинской. Установлено, что сорта Шортандинская 2, Карагандинская 1, Карабалыкская 18, Карабалыкская радуга, Карабалыкская жемчужина, Люция 14, Кокше, Лазурная казахстанской селекции, сорта Уралочка, Находка, Сарга российской селекции выделились формированием наибольшей семенной продуктивности 2,31-2,48 ц/га. Уборку сортов люцерны на семена можно начинать уже в первый год пользования, это не снижает густоту и продуктивность травостоев в последующие годы пользования. Выявлена сортовая реакция люцерны изменчивой при возделывании на семенные цели. Семенная продуктивность на четвертый год пользования по сравнению с третьим у сортов Муслима, Татарская пастбищная, Флора 7, Флора 4 и Ferax снизилась на 20-29%, у сортов Заря, Гюзель, Воронежская 6 и Rhizoma – на 34-37%, у сортов Благодать и Надежда – на 40-44%, у сорта Rangelander – на 50%. Это свидетельствует о нецелесообразности использования травостоев четвертого года пользования на семена.

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Central Scientific Agricultural Library - Russian Federation

2022

Aḥmadī, Amīr | Shahidi, Seyed-Ahmad | Safari, Reza | Motamedzadegan, Ali | Ghorbani-HasanSaraei, Azade

This study aims to the evaluation of stability and antibacterial properties of the extracted chlorophyll from alfalfa. For this purpose, chlorophylls a and b from alfalfa were extracted by enzymatic and ultrasound methods. The results show that the content of chlorophyll a in alfalfa is higher than chlorophyll b and also the enzymatic method demonstrates higher yield in chlorophyll extraction. In the present study, the chlorophyll stability was evaluated in different conditions including temperature (−18, 4 and 25 °C), time (15, 30 and 45 days), pH (4.5 and 5.5) and NaCl concentration (50, 100 and 150 mM). Also, antibacterial effects were investigated at different concentrations of chlorophyll (20, 40, 60 and 100 μM) against some bactriaes by agar disk diffusion and microdilution (MIC and MBC) methods. The results demonstrate that 50 mM of NaCl, temperature −18 °C, pH = 4.5 and time 15 days are associated with the highest chlorophyll a and b contents. Furthermore, the resistance of bacterias in agar disk diffusion and microdilution methods observe Listeria < Staphylococcus < Salmonella < Escherichia < Pseudomonas and Listeria<(Staphylococcus = Escherichia = Salmonella)<Pseudomonas, respectively. Also, there are significant differences between different chlorophyll concentrations against Listeria and Staphylococcus in evaluation of inhibition effects of total extracted chlorophyll (p < 0.05).

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National Agricultural Library - United States of America

2022

Sauviac, Laurent | Rémy, Antoine | Huault, Emeline | Dalmasso, Mélanie | Kazmierczak, Théophile | Jardinaud, Marie‐Françoise | Legrand, Ludovic | Moreau, Corentin | Ruiz, Bryan | Cazalé, Anne‐Claire | Valière, Sophie | Gourion, Benjamin | Dupont, Laurence | Gruber, Véronique | Boncompagni, Eric | Meilhoc, Eliane | Frendo, Pierre | Frugier, Florian | Bruand, Claude

Senescence determines plant organ lifespan depending on aging and environmental cues. During the endosymbiotic interaction with rhizobia, legume plants develop a specific organ, the root nodule, which houses nitrogen (N)‐fixing bacteria. Unlike earlier processes of the legume–rhizobium interaction (nodule formation, N fixation), mechanisms controlling nodule senescence remain poorly understood. To identify nodule senescence‐associated genes, we performed a dual plant‐bacteria RNA sequencing approach on Medicago truncatula–Sinorhizobium meliloti nodules having initiated senescence either naturally (aging) or following an environmental trigger (nitrate treatment or salt stress). The resulting data allowed the identification of hundreds of plant and bacterial genes differentially regulated during nodule senescence, thus providing an unprecedented comprehensive resource of new candidate genes associated with this process. Remarkably, several plant and bacterial genes related to the cell cycle and stress responses were regulated in senescent nodules, including the rhizobial RpoE2‐dependent general stress response. Analysis of selected core nodule senescence plant genes allowed showing that MtNAC969 and MtS40, both homologous to leaf senescence‐associated genes, negatively regulate the transition between N fixation and senescence. In contrast, overexpression of a gene involved in the biosynthesis of cytokinins, well‐known negative regulators of leaf senescence, may promote the transition from N fixation to senescence in nodules.

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National Agricultural Library - United States of America