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In the present study, a polygalacturonase (PG) gene was isolated from Brassica campestris L. ssp. chinensis Makino (syn. Brassica rapa ssp. chinensis). Sequence analysis indicated that it contained three classical conserved domains (I, II, and IV) of PG proteins. Phylogenetic analysis demonstrated that it was clustered into the clade E of PG family with several other PGs from different plant species. The results obtained from quantitative reverse transcription-polymerase chain reaction (qRT-PCR) and in situ hybridization showed that the gene, B. campestris Male Fertility 24 (BcMF24), was specifically expressed in the microspores, in the partly degraded tapetum at binucleate stage and in the pollen grains at mature pollen stage. Bioinformatics analysis of a 1,489-bp sequence in the BcMF24 5′-upstream region illustrated that the said gene contained several typical cis-acting elements and pollen-specific elements. Transient expression analysis revealed that BcMF24 can drive the green fluorescent protein (GFP) expression in onion epidermal cells. β-glucuronidase (GUS) assay of the BcMF24 promoter–GUS constructs in transgenic Arabidopsis thaliana showed that it could specifically drive gene expression in the anther of flower buds at binucleate and mature pollen stages. To the best of our knowledge, the current study is the first demonstration of a PG gene, which belongs to clade E that is involved in pollen development.

Plant β-galactosidases (EC 3.2.1.23; BGAL) are associated with cell wall biogenesis and modification. β-Galactosidase isozymes are encoded by the BGAL multigene family in plants. In this study, 16 BcBGAL genes from the Brassica campestris ssp. chinensis (syn. Brassica rapa ssp. chinensis) genome were investigated and compared with those from Arabidopsis thaliana. A comprehensive genome-wide analysis of BcBGAL genes in B. campestris is presented, including their phylogeny, genome localization, gene structure, and expression patterns. Phylogenetic analysis of 16 BcBGAL and 17 AtBGAL proteins from Arabidopsis indicate that the BcBGALs clustered into four major groups, such that genes within the same group had similar exon–intron structures. The 5′-upstream region of BcBGAL genes contained a group of putative cis-acting elements related to stress and plant hormone response. Expression analysis of BcBGAL genes using quantitative reverse transcription–polymerase chain reaction demonstrates that all BcBGAL transcripts could be detected in at least one type of tissue. Some of these transcripts exhibited tissue-specific expression patterns. Our data provided insights on the evolution of the BGAL gene family and a useful reference for further functional analysis in B. campestris.