Identification and expression profiling of microRNAs involved in the stigma exsertion under high-temperature stress in tomato

Abstract

BackgroundAutogamy in cultivated tomato varieties is a derived trait from wild type tomato plants, which are mostly allogamous. However, environmental stresses can cause morphological defects in tomato flowers and hinder autogamy. Under elevated temperatures, tomato plants usually exhibit the phenotype of stigma exsertion, with severely hindered self-pollination and fruit setting, whereas the inherent mechanism of stigma exsertion have been hitherto unknown. Numerous small RNAs (sRNAs) have been shown to play significant roles in plant development and stress responses, however, none of them have been studied with respect to stamen and pistil development under high-temperature conditions. We investigated the associations between stigma exsertion and small RNAs using high-throughput sequencing technology and molecular biology approaches.ResultsSixteen sRNA libraries of Micro-Tom were constructed from plants stamen and pistil samples and sequenced after 2 d and 12 d of exposure to heat stress, respectively, from which a total of 110 known and 84 novel miRNAs were identified. Under heat stress conditions, 34 known and 35 novel miRNAs were differentially expressed in stamens, and 20 known and 10 novel miRNAs were differentially expressed in pistils. GO and KEGG pathway analysis showed that the predicted target genes of differentially expressed miRNAs were significantly enriched in metabolic pathways in both stamen and pistil libraries. Potential miRNA-target cleavage cascades that correlated with the regulation of stigma exsertion under heat stress conditions were found and validated through qRT-PCR and RLM-5′ RACE.ConclusionOverall, a global spectrum of known and novel miRNAs involved in tomato stigma exsertion and induced by high temperatures were identified using high-throughput sequencing and molecular biology approaches, laying a foundation for revealing the miRNA-mediated regulatory network involved in the development of tomato stamens and pistils under high-temperature conditions.Electronic supplementary materialThe online version of this article (10.1186/s12864-017-4238-9) contains supplementary material, which is available to authorized users.

Floral Biology Studies in Habanero pepper (Capsicum chinense Jacq.) to Implement in a Cross-Breeding Program

“…Larrinaga et al [24], studying the floral morphology of Narcissus cyclamineus (Amaryllidaceae), observed that the relative position of the stigmas and anthers has a significant effect on the success of female reproduction. Similarly, information has been reported for tomato by Pan et al [25], indicating that autogamy is usually associated with the position of the anther in relation to the stigma. In cross-pollination, the stigmatic surface receives the pollen of the neighboring flowers, while the self-pollinated flowers are typically characterized by a stigmatic surface that is imbedded inside their own anther.…”

Potato Virus Y Infection Alters Small RNA Metabolism and Immune Response in Tomato

“…Searches in the Tomato Functional Genomics Database for small RNAs [65] identified a homologous miRNA named M00093 ( Figure S6a). Although this miRNA family was neither retrieved in the miRBase nor identified as a novel miRNA by our own analysis, it was found in the literature, described as sly-miR00093 [66] or as tomato novel miRNA pc-27 [67]. Sly-miR00093 was predicted to target at least other seven RLPs which were closely related to Cf-9 ( Figure S6b).…”

Tomato stigma exsertion induced by high temperature is associated with the jasmonate signalling pathway

“…First‐strand cDNA was generated using the PrimeScript™ RT Reagent Kit according to the manufacturer's protocol (TaKaRa, Japan). Quantitative RT‐PCR reactions were performed in a Bio‐Rad CFX96 (Bio‐Rad, USA) using SYBR® Green Realtime PCR Master Mix (TaKaRa, Japan) following the method described in our previous study (C. Pan et al, ). Gene‐specific primers were designed according to the reference gene sequences (Table S1).…”

“…The control plants (CK) were kept under normal conditions. As previously described, flower buds with lengths of 6.0-6.5 mm represent the binucleate pollen stage in tomato cultivar "Micro-Tom" (C. Pan et al, 2017). In order to exclude the impact of different developmental stages, stamens and pistils stripped from flower buds of 6.0-6.5 mm in length were simultaneously sampled at 2 and 12 days under HT and control conditions, respectively.…”