背景:荚大小是花生育种的重要产量目标性状。然而,花生荚大小测定的分子机制仍不清楚。
结果:在这项研究中,两个具有不同豆荚大小的花生品种用于比较转录组和内源性激素水平的差异。在钉住(DAP)后10、15、20、25和30天采样发育中的花生荚。结果表明,花生膨化过程可分为三个阶段:渐进生长期,快速增长阶段和缓慢增长阶段。细胞学分析证实,在快速生长阶段细胞数量的较快增加是Lps中形成较大果荚的主要原因。转录组分析表明,与生长素相关的关键基因的表达,在快速生长阶段,细胞分裂素(CK)和赤霉素(GA)大多上调。同时,细胞分裂相关的差异表达基因(DEGs)大多在10DAP上调,这与细胞学观察结果一致.此外,通过液相色谱与串联质谱(LC-MS/MS)进行植物激素的绝对定量,和结果支持比较转录组学研究的发现。
结论:推测TAA1和ARF(生长素相关)的差异表达水平,IPT和B-ARR(CK相关),KAO,GA20ox和GA3ox(GA相关),某些细胞分裂相关基因(基因-LOC112747313和基因-LOC112754661)是花生荚大小确定机制的重要参与因素。这些结果为阐明花生豆荚生长中的潜在调控网络提供了信息,并将有助于进一步鉴定有价值的目标基因。
BACKGROUND: Pod size is an important yield target trait for peanut breeding. However, the molecular mechanism underlying the determination of peanut pod size still remains unclear.
RESULTS: In this study, two peanut varieties with contrasting pod sizes were used for comparison of differences on the transcriptomic and endogenous hormonal levels. Developing peanut pods were sampled at 10, 15, 20, 25 and 30 days after pegging (DAP). Our results showed that the process of peanut pod-expansion could be divided into three stages: the gradual-growth stage, the rapid-growth stage and the slow-growth stage. Cytological analysis confirmed that the faster increase of cell-number during the rapid-growth stage was the main reason for the formation of larger pod size in Lps. Transcriptomic analyses showed that the expression of key genes related to the auxin, the cytokinin (CK) and the gibberellin (GA) were mostly up-regulated during the rapid-growth stage. Meanwhile, the cell division-related differentially expressed genes (DEGs) were mostly up-regulated at 10DAP which was consistent with the cytological-observation. Additionally, the absolute quantification of phytohormones were carried out by liquid-chromatography coupled with the tandem-mass-spectrometry (LC-MS/MS), and results supported the findings from comparative transcriptomic studies.
CONCLUSIONS: It was speculated that the differential expression levels of TAA1 and ARF (auxin-related), IPT and B-ARR (CK-related), KAO, GA20ox and GA3ox (GA-related), and certain cell division-related genes (gene-LOC112747313 and gene-LOC112754661) were important participating factors of the determination-mechanism of peanut pod sizes. These results were informative for the elucidation of the underlying regulatory network in peanut pod-growth and would facilitate further identification of valuable target genes.