Disassembly of the fruit cell wall by the ripening-associated polygalacturonase and expansin influences tomato cracking
Disassembly of the fruit cell wall by the ripening-associated polygalacturonase and expansin influences tomato cracking
复制标题
成熟相关的多聚半乳糖醛酸酶和扩展蛋白对果实细胞壁的分解影响番茄开裂
DOI：
10.1038/s41438-018-0105-3
复制
发表时间：
2019-02-01
影响因子：
8.7
通讯作者：
Mitcham, Elizabeth
中科院分区：
文献类型：
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作者：
Jiang, Fangling;Lopez, Alfonso;Mitcham, Elizabeth
裂果是园艺作物生产中的一个重要问题。多聚半乳糖醛酸酶（SlPG）和扩展蛋白（SlEXP 1）蛋白在成熟过程中协同分解番茄果实细胞壁的多糖网络，从而使其软化。作为一种类GLK 2转录因子，SlGLK 2调节未成熟果实叶绿体的发育，并导致成熟果实中可溶性固形物和类胡萝卜素的升高。为了确定SlPG、SlEXP 1或SlGLK 2是否影响番茄果实开裂的速率，在野生型、Ailsa克雷格（WT）和具有抑制的SlPG和SlEXP 1表达（pg/exp）或表达截短的非功能性Slglk 2（glk 2）的果实之间比较果实表皮开裂的发生率。用外源阿坝处理植物增加了木质素流入果实。我们的研究结果表明，阿坝处理番茄植株大大增加了野生型和glk 2突变体的裂果，但没有从pg/exp基因型。pg/exp基因型果实硬度、可溶性固形物含量高，细胞壁致密，角质层较厚。来自阿坝处理的pg/exp果实的果实具有比来自其他品系的果实具有更少水溶性和更多离子和共价结合的果胶的细胞壁，表明果实细胞壁的成熟相关的分解，但不消除SlGLK 2，影响开裂。开裂率与细胞壁厚度、蜡质厚度、细胞壁原果胶和纤维素含量呈显著正相关，而与Ca 2+含量无显著相关性。
Fruit cracking is an important problem in horticultural crop production. Polygalacturonase (SlPG) and expansin (SlEXP1) proteins cooperatively disassemble the polysaccharide network of tomato fruit cell walls during ripening and thereby, enable softening. A Golden 2-like (GLK2) transcription factor, SlGLK2 regulates unripe fruit chloroplast development and results in elevated soluble solids and carotenoids in ripe fruit. To determine whether SlPG, SlEXP1, or SlGLK2 influence the rate of tomato fruit cracking, the incidence of fruit epidermal cracking was compared between wild-type, Ailsa Craig (WT) and fruit with suppressed SlPG and SlEXP1 expression (pg/exp) or expressing a truncated nonfunctional Slglk2 (glk2). Treating plants with exogenous ABA increases xylemic flow into fruit. Our results showed that ABA treatment of tomato plants greatly increased cracking of fruit from WT and glk2 mutant, but not from pg/exp genotypes. The pg/exp fruit were firmer, had higher total soluble solids, denser cell walls and thicker cuticles than fruit of the other genotypes. Fruit from the ABA treated pg/exp fruit had cell walls with less water-soluble and more ionically and covalently-bound pectins than fruit from the other lines, demonstrating that ripening-related disassembly of the fruit cell wall, but not elimination of SlGLK2, influences cracking. Cracking incidence was significantly correlated with cell wall and wax thickness, and the content of cell wall protopectin and cellulose, but not with Ca 2+ content.