First report of peanut root rot caused by Fusarium acuminatum in Shandong Province, China.

Peanut (Arachis hypogaea L.) is one of the most economically important crops as a major source of edible oil and protein. In July 2021, a root rot disease was observed on peanut in Laiwu (36º22' N, 117º67' E), Shandong Province, China. Disease incidence was approximately 35%. Disease symptoms included root rot, vessels with a brown to dark brown discoloration, plus progressive yellowing and wilting of leaves from the base leading to whole plant death. To determine the causal agent, symptomatic roots with typical lesions were cut into small pieces, surface sterilized in 75% ethanol for 30 s, and 2% NaClO for 5 min, rinsed three times in sterile water and placed on potato dextrose agar (PDA) at 25℃ (Leslie and Summerell 2006). After 3 days of incubation, whitish-pink to red colonies growing from the roots were observed. Eight single-spore isolates had identical morphological traits that were similar to those of Fusarium spp. A representative isolate (LW-5) was used for morphological characterization, molecular analysis, and pathogenicity test. On PDA, the isolate formed dense aerial mycelia, which were initially white, then became deep pink with age and formed red pigments in the medium. On carnation leaf agar (CLA), macroconidia with 3 to 5 septa were abundant, relatively slender, curved to lunate, that measured 23.7 to 52.2 × 3.6 to 5.4 µm (n=50). Microconidia were oval, 0 to 1 septa. Chlamydospores were globose with a smooth outer wall in chains or single. Following DNA extraction of isolate LW-5, primers EF1-728F/EF1-986R (Carbone et al., 1999), RPB1U/RPB1R, and RPB2U/RPB2R (Ponts et al., 2020) were used to amplify the partial translation elongation factor 1 alpha (TEF1-α), RNA polymerase II largest subunit (RPB1), and RNA polymerase II second largest subunit (RPB2) regions for DNA sequencing, respectively. BLASTn analysis of TEF1-α (GenBank accession No. OP838084), RPB1 (OP838085), and RPB2 (OP838086) sequences, revealed 99.66, 99.87, and 99.09% identity with those of F. acuminatum (OL772800, OL772952 and OL773104), respectively. Isolate LW-5 was identified as F. acuminatum based on morphology and molecular analysis. Twenty Huayu36 peanut seeds were each planted in a 500-ml sterile pot containing 300 g of autoclaved potting medium (nutritive soil: vermiculite=2:1 in volume). Two weeks after seedling emergence, 1 cm depth of the potting medium was dug around the plants to expose the taproot. Two 5-mm wounds per taproot were scratched with a sterile syringe needle. Potting medium in each pot of 10 inoculated plants was mixed with 5 ml of conidial suspension (106 conidia per ml). The other 10 plants were used as non-inoculated controls and treated with sterile water in the same manner. The seedlings were placed in a plant growth chamber maintained at 25°C, RH >70%, 16-h light per day, and irrigated with sterile water. After 4 weeks, inoculated plants exhibited yellowing and wilting symptoms that were similar to those observed in the field, while non-inoculated control plants had no symptoms. F. acuminatum was re-isolated from diseased roots and confirmed using morphological features and DNA sequence analysis of TEF1-α, RPB1 and RPB2. F. acuminatum was reported to cause root rot on Ophiopogon japonicus (Linn. f.) (Tang et al., 2020), Polygonatum odoratum (Li et al., 2021), and Schisandra chinensis (Shen et al., 2022) in China. To our knowledge, this is the first report of root rot on peanut caused by F. acuminatum in Shandong Province, China. Our report will provide crucial information for studying the epidemiology and management of this disease.

Integrated analyses of transcriptome and metabolome provides new insights into the primary and secondary metabolism in response to nitrogen deficiency and soil compaction stress in peanut roots.

Peanut (Arachis hypogaea L.) is an important oil crop globally because of its high edible and economic value. However, its yield and quality are often restricted by certain soil factors, especially nitrogen (N) deficiency, and soil compaction. To explore the molecular mechanisms and metabolic basis behind the peanut response to N deficiency and soil compaction stresses, transcriptome and metabolome analyses of peanut root were carried out. The results showed that N deficiency and soil compaction stresses clearly impaired the growth and development of peanut's aboveground and underground parts, as well as its root nodulation. A total of 18645 differentially expressed genes (DEGs) and 875 known differentially accumulated metabolites (DAMs) were identified in peanut root under differing soil compaction and N conditions. The transcriptome analysis revealed that DEGs related to N deficiency were mainly enriched in "amino acid metabolism", "starch and sucrose metabolism", and "TCA cycle" pathways, while DEGs related to soil compaction were mainly enriched in "oxidoreductase activity", "lipids metabolism", and "isoflavonoid biosynthesis" pathways. The metabolome analysis also showed significant differences in the accumulation of metabolisms in these pathways under different stress conditions. Then the involvement of genes and metabolites in pathways of "amino acid metabolism", "TCA cycle", "lipids metabolism", and "isoflavonoid biosynthesis" under different soil compaction and N deficiency stresses were well discussed. This integrated transcriptome and metabolome analysis study enhances our mechanistic knowledge of how peanut plants respond to N deficiency and soil compaction stresses. Moreover, it provides new leads to further investigate candidate functional genes and metabolic pathways for use in improving the adaptability of peanut to abiotic stress and accelerating its breeding process of new stress-resistant varieties.

Report of the Texas peanut root-knot nematode, Meloidogyne haplanaria (Tylenchida: Meloidogynidae) from American pitcher plants (Sarracenia sp.) in California.

During the winter and spring of 2021, the root-knot nematodes were extracted from samples of galled roots of potted American pitcher plants (Sarracenia sp.). Samples were collected from a botanical garden nursery in Los Angeles County, California. The root-knot nematode was identified by molecular methods as Meloidogyne haplanaria. In the USA, M. haplanaria was initially found in Texas, and subsequently reported from Arkansas and Florida. Molecular characterization of the Californian M. haplanaria isolate was done using the analysis of the D2-D3 of 28S rRNA, ITS rRNA, mitochondrial l-rRNA, COI, and nad5 gene sequences. Some rRNA gene clusters of M. haplanaria were similar with those of M. arenaria. Possible hybridization events within mitotic parthenogenetic root-knot nematodes are discussed. This study confirmed that reliable diagnostics of M. haplanaria should be based on mtDNA sequence analysis. This is a first report of M. haplanaria from Sarracenia sp. and California. Consequently, this nematode was considered to be eradicated from this botanical garden nursery and the State of California.

Effects of P limitation and molecules from peanut root exudates on pqqE gene expression and pqq promoter activity in the phosphate-solubilizing strain Serratia sp. S119.

The mineral phosphate-solubilizing phenotype in bacteria is attributed predominantly to secretion of gluconic acid produced by oxidation of glucose by the glucose dehydrogenase enzyme and its cofactor, pyrroloquinoline quinone. This study analyzes pqqE gene expression and pqq promoter activity in the native phosphate-solubilizing bacterium Serratia sp S119 growing under P-limitation, and in the presence of root exudates obtained from peanut plants, also growing under P-limitation. Results indicated that Serratia sp. S119 contains a pqq operon composed of six genes (pqqA,B,C,D,E,F) and two promoters, one upstream of pqqA and other between pqqA and pqqB. PqqE gene expression and pqq promoter activity increased under P-limiting growth conditions and not under N-deficient conditions. In the plant-bacteria interaction assay, the activity of the bacterial pqq promoter region varied depending on the concentration and type of root exudates and on the bacterial growth phase. Root exudates from peanut plants growing under P-available and P-limiting conditions showed differences in their composition. It is concluded from this study that the response of Serratia sp. S119 to phosphorus limitation involves an increase in expression of pqq genes, and that molecules exuded by peanut roots modify expression of these phosphate-solubilizing bacterial genes during plant-bacteria interactions.

Inhibiting effect of ethanol extract from peanut root on rat prostate hyperplasia and its influence on Bcl-2 and Bax protein / 重庆医学

Objective To explore the inhibitory effect of the ethanol extract from peanut root on the non-castration adult rat prostate hyperplasia induced by testosterone propionate and its mechanism .Methods 60 SD rats were randomly divided into the control ,model and high ,middle and low dose of peanut root ethanol extract treatment groups ,among them ,the control group was normally fed without medication ;the model group was subcutaneously injected by testosterone propionate (TP ,5 mL/kg/d) and simultaneously gavaged subcutaneous injection with peanut root ethanol extract (10 mL/kg/d ,5 mLg/kg/d or 1 mL/kg/d) for suc-cessive 14 d .The rats in various groups were killed on 15 d and their prostate ,spermatophore and testicle tissues were separated and weighed .The ratio of gland/body-weight(mg/g) was calculated .The expressions of Bcl-2 and Bax proteins in the prostate tissues were detected by immunohistochemistry .Results There was statistical difference in the indexes of prostate between the treatment groups(high and middle dose) and the model group(P0 .05) .This result showed that there was a dose-effect relationship between the inhibition effect on rat prostate hyperplasia and the ethanol extracts from peanut root .There was no statistical differences between the model group and the treatment groups in the indexes of testicle ,spermatophore or the change of weight (P>0 .05) .There was statistical difference be-tween the control group or model group and the treatment group in the expression of Bcl-2 or Bax protein(P0 .05) .Conclusion Ethanol extract from peanut root has good inhibiting effect on prostate hyperplasia and its mechanism could reach the curative effect by regulating the balance relation be-tween apoptosis gene Bcl-2 and Bax protein proportion and promoting apopitosis of benign prostatic hyperplasia .

Resistance in Selected Corn Hybrids to Meloidogyne arenaria and M. incognita.

A total of 33 corn hybrids were evaluated in a series of greenhouse and field trials to determine if they differed in resistance to either Meloidogyne incognita race 3 or M. arenaria race 1. Reproduction of M. incognita race 3 and M. arenaria race 1 on the hybrids was also compared. Reproduction of M. arenaria differed among corn hybrids after 58 to 65 days in greenhouse experiments; however, reproduction was similar among hybrids in the field experiment. No hybrids were consistently resistant to M. incognita. Two isolates of M. arenaria and two of M. incognita were evaluated in the greenhouse trials, and no evidence of isolate-dependent resistance was observed. Meloidogyne incognita reproduced better than M. arenaria on the hybrids in this study. A survey of 102 corn fields from 11 counties throughout southern Georgia was conducted to determine the relative frequency of M. incognita and M. arenaria. Meloidogyne species were found in 34 of the fields surveyed, and 93.9% of these were identified as M. incognita. The frequency of occurrence of M. incognita was 99.6% if the previous crop was cotton and 84.6% if the previous crop was peanut. Pratylenchus spp. were extracted from all intact corn root systems examined.

Genetic Analysis of Meloidogyne arenaria Race 1 Resistance in Tobacco.

Inheritance of resistance to the peanut root-knot nematode (Meloidogyne arenaria (Neal) Chitwood race 1) was investigated in the flue-cured tobacco cv. Speight G 28 and the breeding lines 81-RL-2K and SA 1214. The genetic relationship of this resistance in Speight G 28 to the resistance of the same cultivar to races 1 and 3 of M. incognita was also studied. Crosses were made between the root-knot nematode-susceptible flue-cured tobacco cv. NC 2326 and the three resistant genotypes. Parental, F1, F2 and backcross generations (BC1P1, BC1P2) were grown for each cross in randomized complete block designs with five replications in the greenhouse. Data indicated that resistance to M. arenaria race 1 in the three resistance sources is conditioned by a single dominant gene, but this resistance is partial compared to that for M. incognita races 1 and 3. Further, resistance to races 1 and 3 of M. incognita and resistance to M. arenaria race 1 in cv. Speight G 28 appear to be controlled by the same gene. These results, combined with the absence of segregation in the F2 populations of the crosses between resistant parents 81-RL-2K × SA 1214, 81-RL-2K × Speight G 28, and SA 1214 × Speight G 28, suggest allelism of resistance among these genotypes.

Survey of crop losses in response to phytoparasitic nematodes in the United States for 1994.

Previous reports of crop losses to plant-parasitic nematodes have relied on published results of survey data based on certain commodities, including tobacco, peanuts, cotton, and soybean. Reports on crop-loss assessment by land-grant universities and many commodity groups generally are no longer available, with the exception of the University of Georgia, the Beltwide Cotton Conference, and selected groups concerned with soybean. The Society of Nematologists Extension Committee contacted extension personnel in 49 U.S. states for information on estimated crop losses caused by plant-parasitic nematodes in major crops for the year 1994. Included in this paper are survey results from 35 states on various crops including corn, cotton, soybean, peanut, wheat, rice, sugarcane, sorghum, tobacco, numerous vegetable crops, fruit and nut crops, and golf greens. The data are reported systematically by state and include the estimated loss, hectarage of production, source of information, nematode species or taxon when available, and crop value. The major genera of phytoparasitic nematodes reported to cause crop losses were Heterodera, Hoplolaimus, Meloidogyne, Pratylenchus, Rotylenchulus, and Xiphinema.

Reproduction of Meloidogyne incognito and M. arenaria on Tropical Corn Hybrids.

Reproduction ofMeloidogyne incognita and M. arenaria was determined on 25 commercial tropical corn hybrids in greenhouse studies. Soil around corn seedlings was infested with 3,000 eggs/plant. Reproduction was quantified from counts of egg masses on roots stained with phloxine B 60 days after soil infestation. All of the tropical hybrids were susceptible to M. incognita and M. arenaria. Egg mass indices (0-5 scale) ranged from 3.4 to 4.2 and from 3.4 to 4.1 for M. incognita and M. arenaria, respectively.

Effect of Temperature on Attachment, Development, and Interactions of Pasteuria penetrans on Meloidogyne incognita.

The effect of temperature (10, 20, 25, 30, and 35 C) on attachment and development of Pasteuria penetrans on Meloidogyne arenaria race 1 was elevated in growth chambers. The greatest attachment rate of endospores of P. penetrans occurred on second-stage juveniles at 30 C. The bacterium developed more quickly within its host at 30 and 35 C than at 25 C or below. The development of the bacterium within the nematode female was divided into nine recognizable life stages, which ranged from early vegetative thalli to mature sporangia. Mature sporangium was the predominant life stage observed after 35, 40, 81, and 116 days at 35, 30, 25, and 20 C, respectively. The body width and length of M. arenaria females infected with P. penetrans were smaller initially than the same dimensions in uninfected females, but became considerably larger over time at 25, 30, and 35 C. This isolate of P. penetrans also parasitized and completed its life cycle in males of M. arenaria.

Population Development of Pasteuria penetrans on Meloidogyne arenaria.

A microplot study on the influence of cropping sequences with peanut in summer and bare fallowed or cover crops of rye or vetch in winter on the population development of Pasteuria penetrans was initiated in the spring of 1987. The number of spores of P. penetrans attached per second-stage juvenile of Meloidogyne arenaria race 1 increased from 0.11 in the fall of 1987 to 7.6, 8.6, and 3.6 in the fall of 1989 in the rye, vetch, and fallowed plots, respectively. Higher (P

Aggressiveness and Reproduction of Four Meloidogyne arenaria Populations on Soybean.

Aggressiveness and reproduction differed among four geographical populations of M. arenaria on six soybean cultivars in field microplots. These differences were consistent over 3 years. The populations did not differ in virulence; i.e., population by cultivar interactions were not significant. Perineal pattern morphology, the North Carolina differential host test, chromosome counts of immature oocytes, and esterase phenotypes confirmed that the four populations were M. arenaria. Three populations were host race 2 and one population was host race 1.

Meloidogyne arenaria Populations on Soybean.

The distribution of Meloidogyne spp. was determined in the Piedmont and Coastal Plains soybean production areas of South Carolina. Meloidogyne arenaria, M. incognita, and M. javanica were found in six of seven counties surveyed, with some populations consisting of two or more species. Because M. arenaria populations did not reproduce on peanut (Arachis hypogaea cv. Florunner), they were designated as Host Race 2. Severity of root galling, shoot and root growth, seed yield, and nematode reproduction were examined in fields infested with M. arenaria at Govan and Pelion, South Carolina, using soybean cultivars differing in host suitability to M. arenaria. When different responses in shoot and root growth, seed yield, and nematode reproduction in the two locations were found, soil influences were examined in duplicate field microplot experiments. Soybean growth was affected more by soil influences than by nematode populations; however, the two M. arenaria populations differed in amount of galling and rate of reproduction.

Host Suitability of Commercial Corn Hybrids to Meloidogyne arenaria and M. incognita.

The host suitability of 64 commercial corn hybrids for a Meloidogyne arenaria race 2 population and a M. incognita race 4 population was determined in greenhouse experiments. 'Northrup King 508' and 'Pioneer Brand 3147' maintained M. arenaria below and at the initial population level, respectively, indicating that these hybrids are relatively poor hosts for this species. RF values (final egg number/initial egg number) of the hybrids for M. arenaria ranged from 0.8 for Northrup King 508 to 42.3 for 'Pioneer Brand XC941'. All hybrids were excellent hosts for M. incognita with RF values ranging from 20.7 for 'Sunbelt 1860' to 49.5 for Pioneer Brand XC941.