BrCWM Mutation Disrupted Leaf Flattening in Chinese Cabbage (Brassica rapa L. ssp. pekinensis).

Leaf flattening plays a vital role in the establishment of plant architecture, which is closely related to plant photosynthesis and, thus, influences the product yield and quality of Chinese cabbage. In this study, we used the doubled haploid line 'FT' of Chinese cabbage as the wild type for ethyl methanesulfonate (EMS) mutagenesis and obtained a mutant cwm with stably inherited compact and wrinkled leaves. Genetic analysis revealed that the mutated trait was controlled by a single recessive nuclear gene, Brcwm. Brcwm was preliminarily mapped to chromosome A07 based on bulked segregant RNA sequencing (BSR-seq) and fine-mapped to a 205.66 kb region containing 39 genes between Indel12 and Indel21 using SSR and Indel analysis. According to the whole-genome re-sequencing results, we found that there was only one nonsynonymous single nucleotide polymorphism (SNP) (C to T) within the target interval on exon 4 of BraA07g021970.3C, which resulted in a proline to serine amino acid substitution. The mutated trait co-segregated with the SNP. Quantitative reverse transcriptase polymerase chain reaction (qRT-PCR) revealed that BraA07g021970.3C expression was dramatically higher in 'FT' leaves than that in cwm leaves. BraA07g021970.3C is homologous to AT3G55000 encoding a protein related to cortical microtubule organization. A similar phenotype of dwarfism and wrinkled leaves was observed in the recessive homozygous mutant cwm-f1 of AT3G55000, and its T3 transgenic lines were restored to the Arabidopsis wild-type phenotype through ectopic overexpression of BraA07g021970.3C. These results verified that BraA07g021970.3C was the target gene essential for leaf flattening in Chinese cabbage.

BrAN contributes to leafy head formation by regulating leaf width in Chinese cabbage (Brassica rapa L. ssp. pekinensis).

Leafy head is an important agronomic trait that determines the yield and quality of Chinese cabbage. The molecular mechanism underlying heading in Chinese cabbage has been the focus of research, and wide leaves are a prerequisite for leafy head formation. In our study, two allelic leafy heading-deficient mutants (lhd1 and lhd2) with narrow leaf phenotypes were screened in an ethyl methanesulfonate mutagenized population from a heading Chinese cabbage double haploid line 'FT'. Genetic analysis revealed that the mutant trait was controlled by a recessive nuclear gene, which was found to be BraA10g000480.3C by MutMap and Kompetitive allele-specific PCR analyses. As BraA10g000480.3C was the ortholog of ANGUSTIFOLIA in Arabidopsis, which has been found to regulate leaf width by controlling cortical microtubule arrangement and pavement cell shape, we named it BrAN. BrAN in mutant lhd1 carried an SNP (G to A) on intron 2 that co-segregated with the mutant phenotype, and disrupted the exon-intron splice junction generating intron retention and a putative truncated protein. BrAN in mutant lhd2 carried an SNP (G to A) on exon 4 leading to a premature stop codon. The ectopic overexpression of BrAN restored normal leaf phenotype due to abnormal cortical microtubule arrangement and pavement cell shape in the Arabidopsis an-t1 mutant. However, transformation of Bran did not rescue the an-t1 phenotype. These results indicate that BrAN contributes to leafy head formation of Chinese cabbage.

Frequency tracking out-of-lock control in a resonator fiber-optic gyro.

A resonator fiber-optic gyro (RFOG) is being pursued because of its theoretical potential to meet navigation-grade performance with small size, high precision, and lower cost. The stability of the RFOG operation is based on the synchronization of laser frequency to the fiber ring resonator (FRR) resonance frequency. Frequency tracking out-of-lock will lead to peak pulse and zero-bias change at the output of the RFOG, which seriously degrades the performance. First, the influence mechanism of frequency tracking out-of-lock is analyzed. The change of current and temperature in frequency tracking and the symmetry change caused by backscatter and polarization are the main reasons for the peak pulse and zero-bias error. Second, a scheme of out-of-lock control of the RFOG based on temperature closed-loop operation using digital signal processing is proposed. The improved scheme, signal processing, and implementation method are investigated in detail. Finally, a RFOG prototype is assembled and tested, and 10 min tracking of the laser frequency to the FRR's single-resonance frequency is realized by temperature closed-loop operation. The static performance of the RFOG over 1 h shows that the RFOG output errors caused by frequency tracking out-of-lock are successfully eliminated. The output peak pulse is reduced from 3000 to 200 deg/h, the zero bias is eliminated from 50 to 600 deg/h to 0, and the bias stability of the RFOG is improved from 15.2 to 1.85 deg/h, which indicates a remarkable advance in the performance of the RFOG to satisfy civil navigation application requirements.