Amino acid substitutions in homologs of the STAY-GREEN protein are responsible for the green-flesh and chlorophyll retainer mutations of tomato and pepper
Amino acid substitutions in homologs of the STAY-GREEN protein are responsible for the green-flesh and chlorophyll retainer mutations of tomato and pepper
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DOI：
10.1104/pp.108.118430
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发表时间：
2008-05-01
期刊：
影响因子：
7.4
通讯作者：
Giovannoni, James J.
中科院分区：
文献类型：
--
作者：
Barry, Cornelius S.;McQuinn, Ryan P.;Giovannoni, James J.
颜色的变化往往伴随着成熟的开始，导致色彩鲜艳的果实，作为引诱剂，以种子传播的有机体。在许多水果中，包括番茄(Solanum Lycopsicum)和辣椒(Capsicum Annuum)，由于叶绿体转化为有色体，叶绿素含量急剧下降，类胡萝卜素的合成增加。番茄和辣椒的绿肉(Gf)和叶绿素保持器(Cl1)突变在成熟过程中降解叶绿素的能力受到抑制，导致成熟果实的产生，其特征是叶绿素和类胡萝卜素的积累，因此颜色是棕色的。利用定位克隆的方法，我们已经在gf基因座上发现了一个点突变，该突变导致了水稻(Oryza Sativa)保持绿(SGR)蛋白的番茄同源物的不变残基中的氨基酸替换。同样，c1突变也携带了SGR辣椒同源物中不变残基上的氨基酸替换。在果实成熟开始时，GF和CL的表达都被高度诱导，这与成熟相关的叶绿素的下降是一致的。系统发育分析表明，植物中存在两类不同的SGR蛋白。SGR亚家族是叶绿素降解所必需的，并通过一种未知的机制起作用。第二个亚家族，我们称之为SGR-like，有一个尚未定义的功能。
Color changes often accompany the onset of ripening, leading to brightly colored fruits that serve as attractants to seed-dispersing organisms. In many fruits, including tomato (Solanum lycopersicum) and pepper (Capsicum annuum), there is a sharp decrease in chlorophyll content and a concomitant increase in the synthesis of carotenoids as a result of the conversion of chloroplasts into chromoplasts. The green-flesh (gf) and chlorophyll retainer (cl) mutations of tomato and pepper, respectively, are inhibited in their ability to degrade chlorophyll during ripening, leading to the production of ripe fruits characterized by both chlorophyll and carotenoid accumulation and are thus brown in color. Using a positional cloning approach, we have identified a point mutation at the gf locus that causes an amino acid substitution in an invariant residue of a tomato homolog of the STAY-GREEN (SGR) protein of rice (Oryza sativa). Similarly, the cl mutation also carries an amino acid substitution at an invariant residue in a pepper homolog of SGR. Both GF and CL expression are highly induced at the onset of fruit ripening, coincident with the ripening-associated decline in chlorophyll. Phylogenetic analysis indicates that there are two distinct groups of SGR proteins in plants. The SGR subfamily is required for chlorophyll degradation and operates through an unknown mechanism. A second subfamily, which we have termed SGR-like, has an as-yet undefined function.