SD-RLK28 positively regulates pollen hydration on stigmas as a PCP-Bß receptor in Arabidopsis thaliana.

Pollen hydration on dry stigmas is strictly regulated by pollen-stigma interactions in Brassicaceae. Although several related molecular events have been described, the molecular mechanism underlying pollen hydration remains elusive. Multiple B-class pollen coat proteins (PCP-Bs) are involved in pollen hydration. Here, by analyzing the interactions of two PCP-Bs with three Arabidopsis thaliana stigmas strongly expressing S-domain receptor kinase (SD-RLK), we determined that SD-RLK28 directly interacts with PCP-Bß. We investigated pollen hydration, pollen germination, pollen tube growth, and stigma receptivity in the sd-rlk28 and pcp-bß mutants. PCP-Bß acts in the pollen to regulate pollen hydration on stigmas. Loss of SD-RLK28 had no effect on pollen viability, and sd-rlk28 plants had normal life cycles without obvious defects. However, pollen hydration on sd-rlk28 stigmas was impaired and pollen tube growth in sd-rlk28 pistils was delayed. The defect in pollen hydration on sd-rlk28 stigmas was independent of changes in reactive oxygen species levels in stigmas. These results indicate that SD-RLK28 functions in the stigma as a PCP-Bß receptor to positively regulate pollen hydration on dry stigmas.

Genome-wide identification of the valine-glutamine motif containing gene family and the role of VQ25-1 in pollen germination in Brassica oleracea.

BACKGROUND: The plant-specific valine-glutamine (VQ) motif containing proteins tightly regulate plant growth, development, and stress responses. However, the genome-wide identification and functional analysis of Brassica oleracea (B. oleracea) VQ genes have not been reported. OBJECTIVE: To identify the VQ gene family in B. oleracea and analyze the function of Bo25-1 in pollen germination. METHODS: The Hidden Markov Model (HMM) of VQ family was used to query the BoVQ genes in the B. oleracea genome. The BoVQ genes preferentially expressed in anthers were screened by qRT-PCR. Subcellular localization of VQ25-1 was observed in Nicotiana benthamiana (N. benthamiana) leaves. To analysis the role of BoVQ25-1 in pollen germination, the expression of BoVQ25-1 was suppressed using antisense-oligonucleotides (AS-ODN). RESULTS: A total of 64 BoVQ genes were identified in the B. oleracea genome. BoVQ25-1 was found to be preferentially expressed in the B. oleracea anthers. BoVQ25-1 was cloned from the anthers of the B. oleracea cultivar 'Fast Cycle'. BoVQ25-1 is localized to the nucleus. The pollen germination rate significantly decreased after AS-ODN treatment. CONCLUSION: Sixty-four BoVQ genes were identified in the B. oleracea genome, of which BoVQ25-1 plays an important role in pollen germination.

[High quality standard of Scutellariae Radix based on plant metabolomics and index components].

Scutellariae Radix(SR), derived from the dried root of Scutellaria baicalensis in the family Lamiaceae, commonly serves as Chinese medicinal material. Affected by producing areas, growing years, and harvesting periods, the quality of SR fluctuates in the market. However, baicalin≥9% in SR required in the Chinese Pharmacopoeia(2020 edition) can only determine the qualified SR but cannot identify high-quality SR. To improve the quality control methods of SR, the present study analyzed the accumulation of metabolites in SR of different growth years by plant metabolomics, and identified 28 metabolites increasing with growth years(1-3 years). Subsequently, 14 main metabolites were quantitatively analyzed by ultra-high performance liquid chromatography-tandem triple quadrupole mass spectrometry(UPLC-QQQ-MS). Among them, baicalin, wogonoside, baicalein, and wogonin with high content and good activity were selected as the index components of SR for quality evaluation. A high-performance liquid chromatography(HPLC) method was established to determine the content of four index components in 32 batches of SR from different producing areas, harvesting perio-ds, and growth years. The results showed that the growth years could greatly affect the content of index components. The total content of four index components in 2-year SR was the highest, followed by the 3-/4-year SR and 1-year SR. Based on HPLC data and verification results by enterprises, baicalin ≥12.0%, wogonoside ≥2.3%, baicalein ≥0.1%, and wogonin ≥0.03% were proposed as the evaluation criteria for the high-quality SR. The findings of this study are expected to provide a basis for improving the quality of SR.

Dissecting Pistil Responses to Incompatible and Compatible Pollen in Self-Incompatibility Brassica oleracea Using Comparative Proteomics.

Angiosperms have developed self-incompatibility (SI) systems to reject self-pollen, thereby promoting outcrossing. The Brassicaceae belongs to typical sporophytic system, having a single S-locus controlled SI response, and was chosen as a model system to study SI-related intercellular signal transduction. In this regard, the downstream factor of EXO70A1 was unknown. Here, protein two-dimensional electrophoresis (2-DE) method and coupled with matrix-assisted laser desorption ionization/time of flight of flight mass spectrometry (MALDI-TOF -MS) and peptide mass fingerprinting (PMF) was used to further explore the mechanism of SI responses in Brassica oleracea L. var. capitata L. at protein level. To further confirm the time point of protein profile change, total proteins were collected from B. oleracea pistils at 0 min, 1 h, and 2 h after self-pollination. In total 902, 1088 and 1023 protein spots were separated in 0 min, 1 h and 2 h 2-DE maps, respectively. Our analyses of self-pollination profiles indicated that proteins mainly changed at 1 h post-pollination in B. oleracea. Moreover, 1077 protein spots were separated in cross-pollinated 1 h (CP) pistil 2-DE map. MALDI-TOF-MS and PMF successfully identified 34 differentially-expressed proteins (DEPs) in SP and CP 1 h 2-DE maps. Gene ontology and KEGG analysis revealed an array of proteins grouped in the following categories: stress and defense response (35%), protein metabolism (18%), carbohydrate and energy metabolism (12%), regulation of translation (9%), pollen tube development (12%), transport (9%) and cytoskeletal (6%). Sets of DEPs identified specifically in SP or only up-regulated expressed in CP pistils were chosen for funther investigating in floral organs and during the process of self- and cross-pollination. The function of these DEPs in terms of their potential involvement in SI in B. oleracea is discussed.