Defect in BrMS1, a PHD-finger transcription factor, induces male sterility in ethyl methane sulfonate-mutagenized Chinese cabbage (Brassica rapa L. ssp. pekinensis)

Abstract

Male sterility is an ideal character for the female parent in commercial hybrid seed production in Chinese cabbages. We identified three allele male sterile mutants msm2-1/2/3 in progenies of ethyl methane sulfonate mutagenized Chinese cabbage. It was proved that their male sterilities were controlled by a same recessive nuclear gene. Cytological observation showed that the delayed tapetal programmed cell death (PCD) as well as the abnormal pollen exine and intine led to pollen abortion in these mutants. MutMap combined with KASP analyses showed that BraA10g019050.3C, a homologous gene of AtMS1 encoding a PHD-finger transcription factor and regulated pollen development, was the causal gene. A single-nucleotide mutation from G to A occurred at the 2443th base of BrMS1 in msm2-1 which results in premature termination of the PHD-finger protein translation; a single-nucleotide mutation from G to A existed at 1372th base in msm2-2 that makes for frameshift mutation; a single-nucleotide mutation from G to A distributed at 1887th base in msm2-3 which issues in the amino acid changed from Asp to Asn. The three allelic mutations in BrMS1 all led to the male sterile phenotype, which revealed its function in stamen development. Quantitative reverse transcription polymerase chain reaction analysis indicated that BrMS1 specially expressed in the anther at the early stage of pollen development and its expression level was higher in msm2-1/2/3 than that in the wild-type “FT.” BrMS1 was located at the nucleus and a length of 12 amino acid residues at the C-terminus had transcriptional activation activity. RNA-seq indicated that the mutation in BrMS1 affected the transcript level of genes related to the tapetum PCD and pollen wall formation, which brought out the pollen abortion. These male sterile mutants we developed provided a novel gene resource for hybrid breeding in Chinese cabbage.

PHD finger proteins function in plant development and abiotic stress responses: an overview

“…pekinensis ) ( Dong et al., 2022 ). Using MutMap combined with KASP analysis, Dong et al. (2022) screened out a homologous gene of AtMS1 , BrMS1 , which plays a transcriptional regulatory role in tapetal programmed cell death (PCD) and pollen wall development.…”

“…Based on the information from pollen regulatory gene networks in Arabidopsis, several orthologs of AtMS1 have been identified and functionally characterized in various species, such as PERSISTENT TAPETAL CELL1/OsMS1 (OsPTC1/OsMS1) in rice (Li et al, 2011;Yang et al, 2019a), HvMS1 in barley (Hordeum vulgare) (Goḿez and Wilson, 2014), ZmMS7 in maize (Zea mays) (Zhang et al, 2018), and BrMS1 in Chinese cabbage (Brassica rapa L. ssp. pekinensis) (Dong et al, 2022). Using MutMap combined with KASP analysis, Dong et al (2022) screened out a homologous gene of AtMS1, BrMS1, which plays a transcriptional regulatory role in tapetal programmed cell death (PCD) and pollen wall development.…”

“…pekinensis) (Dong et al, 2022). Using MutMap combined with KASP analysis, Dong et al (2022) screened out a homologous gene of AtMS1, BrMS1, which plays a transcriptional regulatory role in tapetal programmed cell death (PCD) and pollen wall development. ZmMS7, encoding a PHD finger transcription factor in maize, shows 80.9% and 40.5% amino acid sequence identities with OsPTC1/OsMS1 and AtMS1, respectively (Zhang et al, 2018).…”

Identification and fine mapping of Brmmd1 gene controlling recessive genic male sterility in Brassica rapa L

“…In another RGMS mutant 7365A, Bnms3 (also known as BnaC.Tic40) was identi ed as the causal gene responsible for abnormal tapetal development in B. napus (Dun et al 2011). Several RGMS systems have been characterized in B. rapa such as Bcajh97-01A/B (Huang et al 2009), AB01-1/2 (Feng et al 2009), WS24-3/WS135 (Li et al 2016), ftms/FT (Tan et al 2019), and msm2/FT (Dong et al 2022). To our knowledge, only two 60 Co γ-rays mutagenesis systems in B. rapa, ftms/FT and msm2/FT have been employed to identify the candidate gene by the forward genetics method.…”

Brems1 mutation induced tapetum deficiency leading to male sterility in Chinese cabbage (Brassica rapa L. ssp. pekinensis)

“…Dysfunction of the tapetum in the Arabidopsis thaliana male-sterile mutant DYT1 resulted in abnormal pollen development (Zhang et al 2006). Several mutants with abnormal tapetum development have been identi ed in Chinese cabbage, including BrMS1 (Dong et al 2022), BrACOS5 (Zou et al 2023), BrGGL7 (Zhao et al 2022), and BrABCG26 (Xu et al 2024).…”