Transcription factors NF-YB involved in embryogenesis and hormones responses in Dimocarpus Longan Lour

Abstract

IntroductionNF-YB transcription factor is an important regulatory factor in plant embryonic development.ResultsIn this study, 15 longan NF-YB (DlNF-YB) family genes were systematically identified in the whole genome of longan, and a comprehensive bioinformatics analysis of DlNF-YB family was performed. Comparative transcriptome analysis of DlNF-YBs expression in different tissues, early somatic embryogenesis (SE), and under different light and temperature treatments revealed its specific expression profiles and potential biological functions in longan SE. The qRT-PCR results implied that the expression patterns of DlNF-YBs were different during SE and the zygotic embryo development of longan. Supplementary 2,4-D, NPA, and PP333 in longan EC notably inhibited the expression of DlNF-YBs; ABA, IAA, and GA3 suppressed the expressions of DlNF-YB6 and DlNF-YB9, but IAA and GA3 induced the other DlNF-YBs. Subcellular localization indicated that DlNF-YB6 and DlNF-YB9 were located in the nucleus. Furthermore, verification by the modified 5'RNA Ligase Mediated Rapid Amplification of cDNA Ends (5' RLM-RACE) method demonstrated that DlNF-YB6 was targeted by dlo-miR2118e, and dlo-miR2118e regulated longan somatic embryogenesis (SE) by targeting DlNF-YB6. Compared with CaMV35S- actuated GUS expression, DlNF-YB6 and DlNF-YB9 promoters significantly drove GUS expression. Meanwhile, promoter activities were induced to the highest by GA3 but suppressed by IAA. ABA induced the activities of the promoter of DlNF-YB9, whereas it inhibited the promoter of DlNF-YB6.DiscussionHence, DlNF-YB might play a prominent role in longan somatic and zygotic embryo development, and it is involved in complex plant hormones signaling pathways.

Genome-Wide Identification and Expression Analysis Reveals the B3 Superfamily Involved in Embryogenesis and Hormone Responses in Dimocarpus longan Lour.

“…Previous studies have shown that ABA, GA 3 , and auxin play a key role in plants under abiotic stress [ 65 ]. GA 3 regulates the expression of transcription factors related to SE and participates in the process of SE [ 66 ]. It was found that LEC2 reduced ABA levels and promoted somatic embryogenesis by controlling ABA8′-hydroxylase ( CYP707A1/2/3 ) that catabolizes ABA [ 67 , 68 ].…”

“…For exogenous hormone treatment, 2 g 18-day longan ECs were transferred to MS (Coolaber, Beijing, China) liquid medium (2% sucrose (Sinopharm, Beijing, China)) with 2,4-D (1.0 mg/L) (Yeasen, Shanghai, China) at 25 • C with 110 r•min −1 shaking in the dark for five days [80]. And then, the pre-cultured longan ECs were transferred to MS liquid basal medium (2% sucrose), supplemented with GA 3 (3,6,9, and 12 mg/L) (Macklin, Shanghai, China), ABA (3, 6, 9, and 12 mg/L) (Yeasen, Shanghai, China), 2,4-D (0.5, 1.0, 1.5, and 2.0 mg/L), IAA (0.5, 1.0, 1.5, and 2.0 mg/L) (Coolaber, Beijing, China), N-1-Naphthylphthalamic acid (NPA: 5, 10, 20,30, 40, and 50 mg/L) (Coolaber, Beijing, China), and Paclobutrazol (PP333: 0.05, 0.1, 0.3, 1, 2, and 3 mg/L) (Solarbio, Beijing, China) with agitation at 120 rpm at 25 • C under dark conditions for 24 h, with three replicates [66]. Collection began in June when young fruits emerged from their cotyledon; the zygotic embryos of different developmental stages were collected from the cotyledon embryo stage of young fruit, and the zygotic embryos were collected every five days, which were labeled as S1, S2, S3, S4, S5, S6, S7, and S8 in turn [66,80].…”