Rao G U, Paran Ilan
Department of Plant Genetics and Breeding, Agricultural Research Organization, The Volcani Center, P.O. Box 6, Bet Dagan, 50250, Israel.
Plant Mol Biol. 2003 Jan;51(1):135-41. doi: 10.1023/a:1020771906524.
The soft flesh and deciduous fruit of pepper (Capsicum spp.) originated from the wild C. frutescens BG 2816 accession is a complete dominant trait controlled by the S gene. We constructed an F2 population from a cross of BG 2816 (SS) and the bell-type C. annuum cultivar Maor (ss) and determined that S cosegregated with the tomato fruit-specific endo-polygalacturonase (PG) gene. The soft flesh and deciduous fruit phenotypes were observed together in all F2 individuals, indicating a pleiotropic effect of PG on the two traits. We mapped S to pepper chromosome 10 in the region corresponding to that in which PG was previously mapped in tomato. Northern, RT-PCR and western analyses and enzyme activity assays, collectively, indicated that PG is not detected in green, breaker or red fruits of Maor, nor in green fruits of BG 2816. Accumulation of PG mRNA and protein was detected in the fruits of BG 2816, and it increased during ripening from breaker to red stages. The sequence analysis of partial PG cDNA isolated from BG 2816 revealed high homology (87% identity) with the tomato PG. The resemblance of the soft flesh and deciduous fruit phenotypes to PG-associated phenotypes in other fruit crops, the complete linkage between S and PG, and the greater expression of PG in the fruits of BG 2816 than in those of Maor, all strongly indicate that PG is a candidate gene for S.
辣椒（辣椒属）起源于野生的C. frutescens BG 2816的软果肉和落叶果实是由S基因控制的完全显性性状。我们以BG 2816（SS）和甜椒型C. annuum品种Maor（ss）杂交构建了一个F2群体，并确定S与番茄果实特异性内切多聚半乳糖醛酸酶（PG）基因共分离。在所有F2个体中都共同观察到软果肉和落叶果实表型，表明PG对这两个性状具有多效性作用。我们将S定位到辣椒10号染色体上与番茄中PG先前定位区域相对应的区域。Northern、RT-PCR和western分析以及酶活性测定共同表明，在Maor的绿色、转色期或红色果实中以及BG 2816的绿色果实中均未检测到PG。在BG 2816的果实中检测到PG mRNA和蛋白质的积累，并且在从转色期到红色阶段的成熟过程中增加。从BG 2816分离的部分PG cDNA的序列分析显示与番茄PG具有高度同源性（87%同一性）。软果肉和落叶果实表型与其他果实作物中与PG相关的表型相似、S和PG之间的完全连锁以及BG 2816果实中PG的表达高于Maor果实中的表达，所有这些都强烈表明PG是S的候选基因。
