Mapping Of QTLs Underlying Traits Related To The Cooking And Eating Quality Of Rice And Cooked Rice Characteristics & Fine Mapping Of Aroma Gene

The cooking and eating quality of rice has attracted more and more attention recently. In a comprehensive effort to unravel its genetic basis, we conducted a genome-wide analysis of six traits representing the cooking and eating quality of rice grain, namely, amylose content (AC), gel consistency (GC), gelatinization temperature (GT), water absorption (WA), cooked rice elongation (CRE) and volume expansion (VE) using a DH population derived from the anther culture of an F₁ hybrid between WYJ 2 (Japonica) and Zhenshan 97B (indica). For each trait, one to three QTLs were found responsible, which were located on chromosome 1, 2, 3, 6, 11. QTL analysis revealed a major QTL specifying GT, located at the interval RM276-RM121, which should be the same locus as the alkali degeneration gene (alk), while for each of the remaining five traits the QTL explaining the largest proportion of variance was located on the short arm of chromosome 6, centered at RM190 (found in the waxy gene). Our results, combining previous reports, further confirmed that either the waxy gene itself or a genomic region tightly linked to it plays a major role in determining the cooking and eating quality of rice.Aromatic varieties are special germplasms that receive a broad attention worldwide. The second part of my M. Sc. dissertation involved the genetic anaylsis of aroma in rice and the fine mapping of the aroma gene, fgr. Major results obtained in this study are as follows:The leaves of F1 hybrids of Chuanxiang 29A / Basmati 370, Chuanxiang 29A / KDML 105, Jamine / Chuanxiang 29B, Zhongguoxiangdao/ Chuanxiang 29B were identified as aromatic using the KOH method, which proved that the aroma genes in these five varieties are all allelic to each other.763 aromatic recessive lines were identified from over 3200 Minghui 63 / AM 44 F2 individuals. Using this recessive population the aroma gene was delimited to a 170 kb region. A candidate gene, a putative betaine aldehyde dehydrogenase (referred to as OsBAD hereafter) was identified in this region by analyzing the annotations of this region as well as by referring to previous relevant reports. Semi-quantitative RT-PCR analysis...