硬度是番茄仅次于风味的品质决定因子。利用来自番茄野生资源S.pennellii LA0716的渐渗系(IL,introgression line)群体,采用穿刺法测定完全红熟期番茄的果实硬度。结果表明,番茄果实果肩、中部和果蒂3个部位的硬度极显著正相关。根据渐渗系遗传图谱,对影响果实硬度的位点进行了初步定位,共检测到5个可明显提高番茄果实硬度的QTL(q F-p-1、q F-p-2、q F-p-3、q F-p-4与q F-p-11),分别位于第1、2、3、4和11号染色体上,其中q F-p-4贡献率最大;2个可显著降低果实硬度的QTL(q S-p-4和q S-p-10),分别位于第4和10号染色体上,其中q S-p-10效应最大。通过比较分析发现,本研究定位的多数QTL与前人在番茄野生种定位的影响硬度的QTL同位,说明番茄硬度在遗传和进化上可能具有一定的保守性。研究结果为番茄硬度QTL的精细定位、克隆及遗传改良奠定了一定基础。
Fruit firmness is considered as essential trait for tomato fruit quality and ranks as second importance of the tomato evaluation index after fruits flavor. In this study,by using the introgression line( IL) population derived from S. pennellii LA0716,the firmness of tomato were measured in three part of the red mature fruits including fruit shoulder,mid-part and pedicel through puncture test. Our results indicated that there was a significant correlation among different parts of the fruits for the firmness. Based on the genetic map of the introgression line,five QTLs named q F-p-1,q F-p-2,q F-p-3,q F-p-4 and q F-p-11 for increasing the fruit firmness were located on chromosome1,2,3,4 and 11 respectively. In addition,two QTLs named q S-p-4 and q S-p-10 for reducing the firmness of tomato fruit were located on chromosome 4 and 12. Among these QTLs,q F-p-4 accounted for the highest firm variation and q S-p-10 accounted for the highest soft variation. Compared with the firm QTLs that previously identified from other wild tomato species,we found that most of the QTLs were co-localized on the tomato chromosomes. It indicated that the tomato fruit texture might be a trait which was been selected during the domestication. Results obtained in this study would be of great benefit for fine mapping and cloning of the major QTLs which controlled the tomato fruit firmness,and a foundation for the firmness improvement in tomato breeding.