Differentially Expressed Genes between Carrot Petaloid Cytoplasmic Male Sterile and Maintainer during Floral Development

Abstract

Petaloid cytoplasmic male sterility (CMS) is a maternally inherited loss of male fertility due to the complete conversion of stamens into petal-like organs, and CMS lines have been widely utilized in carrot breeding. Petaloid CMS is an ideal model not only for studying the mitochondrial–nuclear interaction but also for discovering genes that are essential for floral organ development. To investigate the comprehensive mechanism of CMS and homeotic organ alternation during carrot flower development, we conducted transcriptome analysis between the petaloid CMS line (P2S) and its maintainer line (P2M) at four flower developmental stages (T1–T4). A total of 2838 genes were found to be differentially expressed, among which 1495 genes were significantly downregulated and 1343 genes were significantly upregulated in the CMS line. Functional analysis showed that most of the differentially expressed genes (DEGs) were involved in protein processing in the endoplasmic reticulum, plant hormone signal transduction, and biosynthesis. A total of 16 MADS-box genes were grouped into class A, B, C, and E, but not class D, genes. Several key genes associated with oxidative phosphorylation showed continuously low expression from stage T2 in P2S, and the expression of DcPI and DcAG-like genes also greatly decreased at stage T2 in P2S. This indicated that energy deficiency might inhibit the expression of B- and C-class MADS-box genes resulting in the conversion of stamens into petals. Stamen petaloidy may act as an intrinsic stress, upregulating the expression of heat shock protein (HSP) genes and MADS-box genes at stages T3 and T4 in P2S, which results in some fertile revertants. This study will provide a better understanding of carrot petaloid CMS and floral development as a basis for further research.

Differentially Expressed Genes Shared by Two Distinct Cytoplasmic Male Sterility (CMS) Types of Silene vulgaris Suggest the Importance of Oxidative Stress in Pollen Abortion

“…The mitochondrial transcriptomes exhibited only very few differences in coverage or editing between F and H [ 12 , 24 ], the plastid transcriptomes were completely identical between F and H [ 25 ]. Our observations contradict some studies, e.g., [ 19 ], which described numerous mitochondrial DE genes between male sterile and male fertile individuals. This discrepancy may be sometimes explained by experimental artifacts.…”

“…We observed the inhibition of several genes related to fatty acid synthesis, wax and cutin formation in S. vulgaris females (two transcripts coding for pectinesterases (DN44106_c0_g1, DN69711_c0_g1), the transcript for UDP-arabinopyranose mutase (DN59301_c0_g4) involved in cell wall modifications [ 52 ]). Genes with similar functions were also inhibited in male sterile individuals e.g., in radish and other crops [ 14 , 15 , 16 , 17 , 18 , 19 , 53 ]. In contrast, the transcripts coding for catabolic enzymes lipases and esterase (DN57332_c1_g2, DN61032_c0_g1), or caleosin (DN54044_c1_g1), functioning in degradation of storage lipids, were upregulated in females ( Table 4 ).…”

“…This discrepancy may be sometimes explained by experimental artifacts. Liu et al [ 19 ] used polyA enrichment for the construction of cDNA library, but this method cannot detect organellar transcripts that lack poly A [ 41 ] and may lead to the underestimation of gene coverage.…”

“…It reveals the transcripts expressed differentially between the genders, which may be involved in the metabolic processes responsible for pollen abortion. Transcriptomic studies have been conducted mainly in crops, where CMS ensures the production of hybrid seed increasing yield [ 14 , 15 , 16 , 17 , 18 , 19 ]. Agricultural species have passed through population bottlenecks during domestication, which reduced their genetic diversity [ 20 , 21 ].…”

Comparative Transcriptome Reveals the Genes’ Adaption to Herkogamy of Lumnitzera littorea (Jack) Voigt

“…KEGG pathway analysis showed that many DEGs were involved in secondary metabolite biosynthesis, including carbon metabolism, ribosome, protein processing in the endoplasmic reticulum and amino acid biosynthesis. Furthermore, plant oxidative phosphorylation that plays an important role in plant floral development ( Liu et al, 2019 ) is also activated.…”