Global Transcriptional Insights of Pollen-Pistil Interactions Commencing Self-Incompatibility and Fertilization in Tea [Camellia sinensis (L.) O. Kuntze]

Abstract

This study explicates molecular insights commencing Self-Incompatibility (SI) and CC (cross-compatibility/fertilization) in self (SP) and cross (CP) pollinated pistils of tea. The fluorescence microscopy analysis revealed ceased/deviated pollen tubes in SP, while successful fertilization occurred in CP at 48 HAP. Global transcriptome sequencing of SP and CP pistils generated 109.7 million reads with overall 77.9% mapping rate to draft tea genome. Furthermore, concatenated de novo assembly resulted into 48,163 transcripts. Functional annotations and enrichment analysis (KEGG & GO) resulted into 3793 differentially expressed genes (DEGs). Among these, de novo and reference-based expression analysis identified 195 DEGs involved in pollen-pistil interaction. Interestingly, the presence of 182 genes [PT germination & elongation (67), S-locus (11), fertilization (43), disease resistance protein (30) and abscission (31)] in a major hub of the protein-protein interactome network suggests a complex signaling cascade commencing SI/CC. Furthermore, tissue-specific qRT-PCR analysis affirmed the localized expression of 42 DE putative key candidates in stigma-style and ovary, and suggested that LSI initiated in style and was sustained up to ovary with the active involvement of csRNS, SRKs & SKIPs during SP. Nonetheless, COBL10, RALF, FERONIA-rlk, LLG and MAPKs were possibly facilitating fertilization. The current study comprehensively unravels molecular insights of phase-specific pollen-pistil interaction during SI and fertilization, which can be utilized to enhance breeding efficiency and genetic improvement in tea.

Self-(In)compatibility Systems: Target Traits for Crop-Production, Plant Breeding, and Biotechnology

“…However, in a similar study, Ma et al (2018) did not find S-RNase homologs, but instead identified other DEGs (e.g., aGtype LecRLK). More recently, Seth et al (2019) constructed coexpression networks to detect transcripts groups with correlated profiles and also identified DEGs in self/crosspollinated pistils. Tissue-specific qRT-PCRs confirmed DEGs in stigma-style and ovary, and support an LSI system that initiates in the style and extends to the ovary with the putative involvement of S-RNase, SRK and SKP genes in self-pollinations.…”

Genome-wide identification and characterization of functionally relevant microsatellites from putative transcription factor genes of tea for efficient genotyping.

“…3). Likewise, second most represented WRKY and CsNAC TFs harbouring highly polymorphic SSR were reported to have functional role in the regulation of biotic [55][56][57] and abiotic stress tolerance (cold and drought stress responses via ABA signalling) in tea [57][58][59]. Similarly, C3H and Myb-related families regulate dormancy status of vegetative buds [60] and accumulation of anthocyanin pigment in tea respectively [9].…”

Transcriptional Regulation: Molecules, Involved Mechanisms, and Misregulation

“…In this special issue, a total of 19 excellent and interesting papers consisting of 11 original research studies, seven reviews, and one communication are published [5,6,7,8,9,10,11,12,13,14,15,16,17,18,19,20,21,22,23]. They cover all subjects of transcriptional regulation, from cis-regulatory elements to transcription factors, chromatin regulators, and ncRNAs.…”

“…As expected in the NGS era, transcriptome analysis by RNA-Seq has been widely used in many studies to elucidate the most varied mechanisms of pathophysiology as well as other relevant biological processes in diverse organisms [5,9,20,21]. Actually, a small number of studies still utilize microarray as a useful approach.…”

“…Indeed, this platform allows one to identify the common pathway(s) of Major Depressive Disorder and glioblastoma [5]. Otherwise, most of the studies employ RNA-Seq to, for example, understand the regulatory system of stringent response in sphingomonads [9] or to unravel molecular insights of phase-specific pollen-pistil interaction during self-incompatibility and fertilization in tea [21]. Additionally, in silico analyses of available transcriptome databases are often very useful when the biological material is scarce or difficult to isolate, as in the case of a study aimed to identify genes that could have a potential role in the oyster larval adhesion at the pediveliger stage [20].…”