Quantitative trait loci influencing fruit-related characteristics of tomato grown in high-temperature conditions |
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Authors: | Kuan-Hung Lin Wei-Lung Yeh Huei-Mei Chen Hsiao-Feng Lo |
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Institution: | (1) Department of Horticulture, National Taiwan University, Taipei, Taiwan, ROC;(2) Graduate Institute of Biotechnology, Chinese Culture University, Taipei, Taiwan, ROC;(3) Biotechnology/Molecular Breeding Unit, AVRDC-The World Vegetable Center, Tainan, Taiwan, ROC; |
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Abstract: | The objective of this study was to identify molecular markers linked to fruit-related traits in the tomato subjected to high
temperatures. In total, 160 F2 plants derived from a cross between a heat-tolerant breeding line, CL5915-93D4-1-0-3 (Solanum esculentum), and a heat-sensitive wild accession, L4422 (S. pimpinellifolium), were grown in a greenhouse. Six traits including fruit number, fruit weight, brix, seed number, fruit setting, and flower
number were scored. The distributions of fruit number, fruit set, flower number, and seed number were skewed towards heat
susceptibility which is known to be characteristic of L4422. Polymorphic bands were generated by PCR-derived methods of RAPD,
ISSR and AFLP Polymorphism, the segregation ratio, and distribution over the genome of the above 3 markers were compared.
Ten linkage groups, ranging 20.6–151.6 cM in size, were constructed with 62 informative markers spanning a total of 776.3 cM.
Fruit-related quantitative trait loci (QTLs) were non-randomly distributed in the tomato genome. For the 6 traits investigated,
21 QTLs were dispersed on linkage groups 2–5. The genetic effects of the various QTLs were differently exhibited, in our study
we have respectively found from 10.5% to 30.2% of the variation explained by the QTL for flower number (FRN4) and brix (BX2).
Thirteen QTL-mapped markers were unique to 1 trait, and 4 markers were linked to more than 1 trait. Among them, QTLs linked
to the I868-470 marker had effects on fruit weight and brix, and a significant positive correlation between these 2 traits
was noted (r = 0.35, P < 0.05). Thus, the I868-470 marker may have the potential for simultaneous selection of high fruit weight and brix. These
markers also allowed us to align genome linkage maps across distantly related species and to reveal the co-localization between
these QTLs and major genes. |
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