Comparative Transcript Profiling of a Male Sterile Cybrid Pummelo and Its Fertile Type Revealed Altered Gene Expression Related to Flower Development

Abstract

Male sterile and seedless characters are highly desired for citrus cultivar improvement. In our breeding program, a male sterile cybrid pummelo, which could be considered as a variant of male fertile pummelo, was produced by protoplast fusion. Herein, ecotopic stamen primordia initiation and development were detected in this male sterile cybrid pummelo. Histological studies revealed that the cybrid showed reduced petal development in size and width, and retarded stamen primordia development. Additionally, disorganized cell proliferation was also detected in stamen-like structures (fused to petals and/or carpel). To gain new insight into the underlying mechanism, we compared, by RNA-Seq analysis, the nuclear gene expression profiles of floral buds of the cybrid with that of fertile pummelo. Gene expression profiles which identified a large number of differentially expressed genes (DEGs) between the two lines were captured at both petal primordia and stamen primordia distinguishable stages. For example, nuclear genes involved in nucleic acid binding and response to hormone synthesis and metabolism, genes required for floral bud identification and expressed in particular floral whorls. Furthermore, in accordance with flower morphology of the cybrid, expression of PISTILLATA (PI) was reduced in stamen-like structures, even though it was restricted to correct floral whorls. Down-regulated expression of APETALA3 (AP3) coincided with that of PI. These finding indicated that, due to their whorl specific effects in flower development, citrus class-B MADS-box genes likely constituted ‘perfect targets’ for CMS retrograde signaling, and that dysfunctional mitochondria seemed to cause male sterile phenotype in the cybrid pummelo.

Induction of parthenogenetic haploid plants using gamma irradiated pollens in ‘Hirado Buntan’ pummelo (Citrus grandis [L.] Osbeck)

“…Guoqing No. 1) (Guo et al, 2004;Zheng et al, 2012). The production of HB haploid plants may also be significant for the breeding of seedless triploid by somatic fusion.…”

Anatomy and transcript profiling of gynoecium development in female sterile Brassica napus mediated by one alien chromosome from Orychophragmus violaceus

“…The mRNA enrichment, RNA fragmentation, the first and second strand cDNA synthesis and purifying, sequencing adaptors ligation and PCR amplification were performed as previously described [60]. After sequencing, the preliminary data processing was also carried out by BGI-Shenzhen, according to the procedure.…”

Transcriptome and metabolome analyses of sugar and organic acid metabolism in Ponkan (Citrus reticulata) fruit during fruit maturation

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