Linkage Mapping and Comparative Transcriptome Analysis of Firmness in Watermelon (Citrullus lanatus)
Linkage Mapping and Comparative Transcriptome Analysis of Firmness in Watermelon (Citrullus lanatus)
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西瓜 (Citrullus lanatus) 硬度的连锁图谱和比较转录组分析
DOI：
10.3389/fpls.2020.00831
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发表时间：
2020-06-16
影响因子：
5.6
通讯作者：
Wang, Xuezheng
中科院分区：
文献类型：
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作者：
Sun, Lei;Zhang, Yushu;Wang, Xuezheng
西瓜果实的质地和品质是由果肉的紧致度决定的。果肉紧致度作为一种品质性状，受多基因控制。明确西瓜果肉硬度的关键调控因子对西瓜遗传育种具有重要意义。本研究以硬肉瓜籽西瓜PI186490为父本，软肉栽培西瓜W1-1为母本，自交F1获得175个F2代。利用散装分离分析(BSA)-Seq分析和分子标记技术初步定位了控制中心果肉硬度的主要基因。最后，主要基因在2号染色体上的6,210,787 ~ 7,742,559 bp之间和8号染色体上的207,553 ~ 403,137 bp之间的物理区间被划分。测定了西瓜果实发育过程中各细胞壁成分和激素的含量，并进行了比较转录组分析。测定了三个果实发育阶段的原胶素、纤维素、半纤维素、吲哚-3-乙酸（IAA）和脱落酸（ABA）含量，并制作了石蜡切片。结果表明，原蛋白、纤维素和半纤维素对果肉硬度的影响趋势相似，而IAA和ABA浓度随着果实的成熟而持续降低。石蜡切片显示，在各个发育阶段，PI186490细胞比W1-1细胞数量更多，排列更紧密，细胞壁边缘更清晰，细胞壁更厚。对W1-1和PI186490果实发育和成熟过程中果肉的RNA样本进行了比较转录组分析。定位间隔转录组分析结果显示，DUF579家族成员cl016033在W1-1和PI186490中存在差异，该基因可能影响细胞壁成分含量，调节西瓜果实果肉硬度，而MADS-box转录因子cl012507可能参与果实成熟调控，影响西瓜果实硬度。
Watermelon fruit texture and quality are determined by flesh firmness. As a quality trait, flesh firmness is controlled by multigenes. Defining the key regulatory factors of watermelon flesh firmness is of great significance for watermelon genetic breeding. In this study, the hard-flesh egusi seed watermelon PI186490 was used as the male parent, the soft-flesh cultivated watermelon W1-1 was used as the female parent, and 175 F2 generations were obtained from selfing F1. Primary mapping of the major genes controlling center flesh firmness was achieved by bulked-segregant analysis (BSA)-Seq analysis and molecular marker technology. Finally, major genes were delimited in the physical interval between 6,210,787 and 7,742,559 bp on chromosome 2 and between 207,553 and 403,137 bp on chromosome 8. The content of each cell wall component and hormone was measured, and comparative transcriptome analysis was performed during fruit development in watermelon. The protopectin, cellulose, hemicellulose, indole-3-acetic acid (IAA) and abscisic acid (ABA) contents were measured, and paraffin sections were made during the three fruit developmental stages. The results revealed that protopectin, celluloses, and hemicelluloses exhibited similar trends for flesh firmness, while the IAA and ABA concentrations continued to decrease with fruit ripening. Paraffin sections showed that PI186490 cells were more numerous, were more tightly packed, had clearer cell wall edges and had thicker cell walls than W1-1 cells at every developmental stage. Comparative transcriptome analysis was conducted on RNA samples of flesh during fruit development and ripening in W1-1 and PI186490. The results from the localization interval transcriptome analysis showed that Cla016033 (DUF579 family member), which may influence the cell wall component contents to adjust the flesh firmness in watermelon fruit, was different in W1-1 and PI186490 and that Cla012507 (MADS-box transcription factor) may be involved in the regulation of fruit ripening and affect the hardness of watermelon fruit.