A study of the heterochronic sense/antisense RNA representation in florets of sexual and apomictic Paspalum notatum

PODIO M; COLONO CM; SIENA LA; ORTIZ JPA; PESSINO SC

BMC GENOMICS

BIOMED CENTRAL LTD

Lugar: Londres; Año: 2021 vol. 22

1471-2164

Apomixis, an asexual mode of plant reproduction, is a genetically heritable traitevolutionarily related to sexuality, which enables the fixation of heterozygous geneticcombinations through the development of maternal seeds. Recently, reference floraltranscriptomes were generated from sexual and apomictic biotypes of Paspalumnotatum, one of the most well-known plant models for the study of apomixis. However,the transcriptome dynamics, the occurrence of apomixis vs. sexual expressionheterochronicity across consecutive developmental steps and the orientation oftranscription (sense/antisense) remain unexplored.ResultsWe produced 24 Illumina TruSeq®/ Hiseq 1500 sense/antisense floral transcriptomelibraries covering four developmental stages (premeiosis, meiosis, postmeiosis, andanthesis) in biological triplicates, from an obligate apomictic and a full sexual genotype.De novo assemblies with Trinity yielded 103,699 and 100,114 transcripts for theapomictic and sexual samples respectively. A global comparative analysis involvingreads from all developmental stages revealed 19,352 differentially expressed sensetranscripts, of which 13,205 (68%) and 6,147 (32%) were up- and down-regulated inapomictic samples with respect to the sexual ones. Interestingly, 100 differentiallyexpressed antisense transcripts were detected, 55 (55%) of them up- and 45 (45%)down-regulated in apomictic libraries. A stage-by-stage comparative analysis showed ahigher number of differentially expressed candidates due to heterochronicitydiscrimination: the highest number of differential sense transcripts was detected atpremeiosis (23,651), followed by meiosis (22,830), postmeiosis (19,100), and anthesis(17,962), while the highest number of differential antisense transcripts were detected atanthesis (495), followed by postmeiosis (164), meiosis (120) and premeiosis (115).Members of the AP2, ARF, MYB and WRKY transcription factor families, as well as theauxin, jasmonate and cytokinin plant hormone families appeared broadly deregulated.Moreover, the chronological expression profile of several well-characterized apomixiscontrollers was examined in detail.ConclusionsThis work provides a quantitative sense/antisense gene expression catalogue coveringseveral subsequent reproductive developmental stages from premeiosis to anthesis forapomictic and sexual P. notatum, with potential to reveal heterochronic expressionbetween reproductive types and discover sense/antisense mediated regulation. Wedetected a contrasting transcriptional and hormonal control in apomixis and sexualityas well as specific sense/antisense modulation occurring at the onset ofparthenogenesis.