College of Horticulture, Nanjing Agricultural University, Weigang NO 1, Nanjing, 210095, Xuanwu District, China.
Key Laboratory of Horticultural Plant Biology and Germplasm Innovation in East China, Ministry of Agriculture, Nanjing, 210095, China.
BMC Plant Biol. 2020 Apr 15;20(1):162. doi: 10.1186/s12870-020-02373-9.
Fruit cracking occurs easily under unsuitable environmental conditions and is one of the main types of damage that occurs in fruit production. It is widely accepted that plants have developed defence mechanisms and regulatory networks that respond to abiotic stress, which involves perceiving, integrating and responding to stress signals by modulating the expression of related genes. Fruit cracking is also a physiological disease caused by abiotic stress. It has been reported that a single or several genes may regulate fruit cracking. However, almost none of these reports have involved cracking regulatory networks.
Here, RNA expression in 0 h, 8 h and 30 h saturated irrigation-treated fruits from two contrasting tomato genotypes, 'LA1698' (cracking-resistant, CR) and 'LA2683' (cracking-susceptible, CS), was analysed by mRNA and lncRNA sequencing. The GO pathways of the differentially expressed mRNAs were mainly enriched in the 'hormone metabolic process', 'cell wall organization', 'oxidoreductase activity' and 'catalytic activity' categories. According to the gene expression analysis, significantly differentially expressed genes included Solyc02g080530.3 (Peroxide, POD), Solyc01g008710.3 (Mannan endo-1,4-beta-mannosidase, MAN), Solyc08g077910.3 (Expanded, EXP), Solyc09g075330.3 (Pectinesterase, PE), Solyc07g055990.3 (Xyloglucan endotransglucosylase-hydrolase 7, XTH7), Solyc12g011030.2 (Xyloglucan endotransglucosylase-hydrolase 9, XTH9), Solyc10g080210.2 (Polygalacturonase-2, PG2), Solyc08g081010.2 (Gamma-glutamylcysteine synthetase, gamma-GCS), Solyc09g008720.2 (Ethylene receptor, ER), Solyc11g042560.2 (Ethylene-responsive transcription factor 4, ERF4) etc. In addition, the lncRNAs (XLOC_16662 and XLOC_033910, etc) regulated the expression of their neighbouring genes, and genes related to tomato cracking were selected to construct a lncRNA-mRNA network influencing tomato cracking.
This study provides insight into the responsive network for water-induced cracking in tomato fruit. Specifically, lncRNAs regulate the hormone-redox-cell wall network, including plant hormone (auxin, ethylene) and ROS (HO) signal transduction and many cell wall-related mRNAs (EXP, PG, XTH), as well as some lncRNAs (XLOC_16662 and XLOC_033910, etc.).
果实容易在不适宜的环境条件下开裂，是果实生产中主要的损伤类型之一。人们普遍认为，植物已经形成了应对非生物胁迫的防御机制和调控网络，这涉及到通过调节相关基因的表达来感知、整合和响应胁迫信号。果实开裂也是一种由非生物胁迫引起的生理病害。据报道，一个或几个基因可能调节果实开裂。然而，几乎没有这些报告涉及到开裂的调控网络。
在这里，我们通过 mRNA 和 lncRNA 测序分析了两个具有不同番茄基因型的果实（LA1698（抗裂，CR）和 LA2683（易裂，CS））在饱和灌溉处理 0h、8h 和 30h 时的 RNA 表达。差异表达的 mRNAs 的 GO 途径主要富集在“激素代谢过程”、“细胞壁组织”、“氧化还原酶活性”和“催化活性”类别中。根据基因表达分析，差异显著表达的基因包括 Solyc02g080530.3（过氧化物酶，POD）、Solyc01g008710.3（甘露聚糖内切-1,4-β-甘露糖苷酶，MAN）、Solyc08g077910.3（扩展蛋白，EXP）、Solyc07g055990.3（果胶酯酶，PE）、Solyc09g075330.3（木葡聚糖内转葡糖苷酶-水解酶 7，XTH7）、Solyc12g011030.2（木葡聚糖内转葡糖苷酶-水解酶 9，XTH9）、Solyc10g080210.2（多聚半乳糖醛酸酶-2，PG2）、Solyc08g081010.2（γ-谷氨酰半胱氨酸合成酶，gamma-GCS）、Solyc09g008720.2（乙烯受体，ER）、Solyc11g042560.2（乙烯响应转录因子 4，ERF4）等。此外，lncRNAs（XLOC_16662 和 XLOC_033910 等）调节其邻近基因的表达，选择与番茄开裂相关的基因构建影响番茄开裂的 lncRNA-mRNA 网络。
本研究为番茄果实水诱导开裂的响应网络提供了新的认识。具体来说，lncRNAs 调节激素-氧化还原-细胞壁网络，包括植物激素（生长素、乙烯）和 ROS（HO）信号转导以及许多细胞壁相关的 mRNAs（EXP、PG、XTH），以及一些 lncRNAs（XLOC_16662 和 XLOC_033910 等）。
