Phytophthora root and stem rot caused by P. sojae is a destructive soybean soil-borne disease found worldwide. Discovery of genes conferring broad-spectrum resistance to the pathogen is a need to prevent the outbreak of the disease. Here, we show that soybean Rps11 is a 27.7-kb nucleotide-binding site-leucine-rich repeat (NBS-LRR or NLR) gene conferring broad-spectrum resistance to the pathogen. Rps11 is located in a genomic region harboring a cluster of large NLR genes of a single origin in soybean, and is derived from rounds of unequal recombination. Such events result in promoter fusion and LRR expansion that may contribute to the broad resistance spectrum. The NLR gene cluster exhibits drastic structural diversification among phylogenetically representative varieties, including gene copy number variation ranging from five to 23 copies, and absence of allelic copies of Rps11 in any of the non-Rps11-donor varieties examined, exemplifying innovative evolution of NLR genes and NLR gene clusters.

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Phytophthora root and stem rot is a devastating disease of soybean [Glycine max (L.) [Merr.] that occurs annually in North America. Plant death and severe yield loss can This article is protected by copyright. All rights reserved. transpire when conditions are favorable for pathogen development. The first objective was to determine the efficacy of oxathiapiprolin as a soybean seed treatment using laboratory inoculum layer assays with different races of Phytophthora sojae. The second objective was to evaluate oxathiapiprolin seed treatments in wide area agronomic field testing using unmanned aerial vehicle (UAV) image-to-data analysis to quantify emergence, vigor, and greenness traits. The final objective was to examine the yield potential of seed treatments with oxathiapiprolin. Using inoculum layer efficacy testing in a growth chamber with P. sojae races 4, 7, or 31, seed treated with oxathiapiprolin had significantly higher visual root growth scores compared to non-treated seed. Across 115 field locations from 2018-2020, UAV remote sensing image analysis at the V2 growth stage indicated oxathiapiprolin in combination with other fungicides had significantly better emergence, more vigor, and more intense greenness compared to non-treated controls. Entries treated with oxathiapiprolin in combination with other fungicides had an average +161 kg/ha yield difference compared to non-treated entries from 2018 to 2020. Oxathiapiprolin as a seed treatment is an effective management tool for soybean producers, providing efficacy against P. sojae, and improving emergence, vigor, greenness, and final yield.

Symptoms observed in maize seedlings growing in the field in the Taree district were reproduced in glasshouse trials. The condition was prevented by applying sodium molybdate to the soil. Grain from certain growers of certified hybrid maize seed produced seedlings susceptible to the deficiency whereas grain from other growers produced seedlings which showed no symptoms. The differences in susceptibility were found to be related to the molybdenum content of the grain which varied from more than 0.40 p.p.m. to less than 0.01 p.p.m. No case of symptoms was observed in seedlings where grain contained more than 0.08 p.p.m. Severe symptoms occurred where grain molybdenum was less than 0.02 p.p.m. Molybdenum applications to female parent rows in seed crops raised the molybdenum content of grain, and prevented or reduced the incidence of symptoms in seedlings grown from this grain.

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