SUMMARYRecessive resistances to plant viruses in the Potyvirus genus have been found to be based on mutations in the plant eukaryotic translation initiation factors, eIF4E and eIF4G or their isoforms. Here we report that natural, monogenic recessive resistance to the Potyvirus Turnip mosaic virus (TuMV) has been found in a number of mustard (Brassica juncea) accessions. Bulked segregant analysis and sequencing of resistant and susceptible plant lines indicated the resistance is controlled by a single recessive gene, recessive TuMV resistance 03 (retr03), an allele of the eukaryotic translation initiation factor 2B-beta (eIF2Bb). Silencing of eIF2Bb in a TuMV-susceptible mustard plant line and expression of eIF2Bb from a TuMV-susceptible line in a TuMV-resistant mustard plant line confirmed the new resistance mechanism. A functional copy of a specific allele of eIF2Bb is required for efficient TuMV infection. eIF2Bb represents a new class of virus resistance gene conferring resistance to any pathogen. eIF2B acts as a guanine nucleotide exchange factor (GEF) for its GTP-binding protein partner eIF2 via interaction with eIF2ÁGTP at an early step in translation initiation. Further genotyping indicated that a single non-synonymous substitution (A120G) in the N-terminal region of eIF2Bb was responsible for the TuMV resistance. A reproducible marker has been developed, facilitating marker-assisted selection for TuMV resistance in B. juncea. Our findings provide a new target for seeking natural resistance to potyviruses and new opportunities for the control of potyviruses using genome editing techniques targeted on eIF2Bb.

Allopolyploid mustard (Brassica juncea L.) is an important part of the U's triangle model of Brassica comprising vegetable, oilseed, and condiment crops. Vegetable B. juncea varieties are widely distributed in China and have been cultivated for a long period of 6000-7000 years (Yang et al., 2016). Tremendous phenotypic variation can be observed in the vegetable varieties of B. juncea, which include leaf-type, stem-type, root-type, and stalk-type varieties according to their edible organs (Qi et al., 2007). Oilseed B. juncea, as one of three major sources of edible oil in Brassica, is mainly distributed in the Indian subcontinent and Northwest China (

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Cavity flow phenomena are encountered in many kinds of aviation vehicles. The flow-induced noise can easily cause structure resonance and fatigue damages. Therefore, the study on the mechanism and effective control methods of cavity noise are very important to engineering applications. A new active control method was proposed based on the deformable cavity in order to mitigate the cavity noise. Large eddy simulation (LES) and computational aeroacoustics (CAA) are combined to simulate a typical open cavity noise. The results show the first mode sound-pressure level (SPL) of tonal noise decreases gradually while the first mode frequency sharply jumps within a small range of the slant angle of the trailing and bottom wall. In addition, with the increase in the slant angle, the decrease of the first mode SPL of tonal noise at Mach 0.6 is more significant than that at Mach 0.85, but the increase of the first mode frequency at Mach 0.85 is more dramatical than that at Mach 0.6. The proposed method can not only reduce the first mode SPL obviously but also increase the first mode frequency dramatically, which makes it different from the natural frequency of the cavity structure and sequentially helps the cavity avoid fatigue damages from resonance.

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