Genetic Map Of Diploid Potato(Solanum Tuberosum L.) And The Qtls Underlying Resistance To Phytophthora Infestans

Potato(Solarium tuberosum L.), an Andean-originated tuber crop, is the fourth most important food crop after rice, wheat, and maize, and is central to global food security. China ranks the first with its potato production. This tuber crop plays an irreplaceable and important role in Chinese food security. Late blight (Phytophthora infestans) is the most devastating disease of potato worldwide. Late blight management is currently based on the application of fungicides, but it imposes high input costs and results in environment pollution. So, potato varieties with durable resistance against late blight are needed urgently. To achieve such varieties, acquiring and deploying genetic resistance resources and comprehensive understanding of molecular mechanisms of the durable resistance are prerequisite.In order to find new late blight resistance resources, genetic maps were constructed and consequently QTL mapping was conducted with a diploid potato population B3C1HP. The main results are as follows:1. With STS, SSR and AFLP markers, we constructed a primary maternal map of population B3C1HP, the total length of which was810cM. Basing on the primary map, we reported the first conditional mapping of QTL in potato. Six conditional QTLs (dPI02, dPI07, dPI09a, dPI09b, dPI09c and dPI12) were detected. All conditional QTLs had temporal expression patterns along with the time courses in each environment. When the conventional mapping was conducted, only one QTL (PI09) was detected, which was the same as dPI09c detected by the conditional mapping method. By comparison with conventional mapping, the conditional method detected more QTLs, especially those with relative small effects and the dynamics of conditional QTLs can be related to the infection process during late blight epidemic.2. Aiming at the late blight resistance, we screened88positional and161functional candidate gene (CG) marker primer pairs, which resulted in88polymorphic CG markers. These88CG markers, together with other28CG markers provided by CIP, were used to construct the combined, paternal and maternal map of population B3C1HP. The combined (total length898cM), paternal (622cM) and maternal (821cM) map of population B3C1HP consist of78,24and47CG markers, respectively.3. IM based on combined map detected three conventional QTLs (PI07, PI09and PI12) and14conditional QTLs (dPI01, dPI02, dPI03, dPI06a, dPI06b, dPI07a, dPI07b, dPI07c, dPI09a, dPI09c, dPH0a, dPI10b, dPI12a and dPI12b). IM and MQM based on paternal map detected two QTLs (dPI06m and dPI07m), with average support interval19.1(IM) and7.0cM (MQM), respectively.4. MQM based on maternal map detected one conventional QTL (PI09) and seven conditional QTLs (dPI02, dPI07, dPI09a, dPI09b, dPI09c, dPI09d and dPI12), with average support interval5.9cM. The QTLs and their dynamics detected by MQM can be validated by results of MCIM and CIM. The QTL regions of MQM are more precise than that of IM, MCIM and CIM. The average support interval,5.9cM, is shorter than the reported24cM.5. According to the results of MQM and MCIM, nine CG markers fell into the QTL support intervals, including six positional CG markers (GP94₁085, GP1291829, DMC42152bf, DMC42144af, Rpi_svntl₃67and STM0003f) and three functional CG markers (STMIU06m, STI0014and STMCL13₂). STI0014and DMC42152bf hit the LOD peak of corresponding QTLs. The CG markers falling into the QTL regions could be used for MAS aiming at the potato resistance against late blight.6. Five segments on potato (DM) genome matched the QTL support intervals of dPI07, dPI09a, dPI09b, dPI09c(PI09)and dPI12. The five segments harbor409,129,206,128and246genes, respectively. The segment of dPI09c (PI09) harbors nine Rpi-vntl.1-like genes and other five NBS-LRR type genes.We consider dPI09c (PI09) as a new and valuable resistance resource against late blight. The results of our research could contribute to the understanding of the molecular mechanism of late blight resistance and these QTLs could be used to target genes for MAS or manipulation to improve the resistance.