Identification of QTLs with additive, epistatic and QTL × development interaction effects for seed dormancy in rice

Abstract

Seed dormancy (SD) is an important agronomic trait affecting crop yield and quality. In this study, one rice population of recombinant inbred lines (RILs) was used to determine the genetic characteristics of SD at the early (4 weeks after heading), middle (5 weeks after heading) and late (6 weeks after heading) development stages. The level of SD decreased with the process of seed development, and the SD was significantly affected by the heading date (HD) and temperature at the early and middle development stages. A total of eight additive quantitative trait loci (QTLs) for SD were identified at three development stages, and more QTLs were expressed at the early and late development stages. Among them, four, one and three additive QTLs were identified at the early, middle and late development stages, respectively. Epistatic QTLs and QTL-by-development interactions were detected by the joint analysis of multi-development phenotypic values, and one additive and two epistatic QTLs were identified. The phenotypic variation of SD explained by each additive, epistatic QTL and QTL × development interaction ranged from 8.0 to 13.5 %, 0.7 to 3.9 % and 1.3 to 2.8 %, respectively. One major QTL qSD7.1 for SD was tightly linked to the major QTL qHD7.4 for HD, which might be applied to reveal the relationship of SD and HD. By comparing chromosomal positions of these additive QTLs with those previously identified, five additive QTLs qSD1.1, qSD2.1, qSD2.2, qSD4.1 and qSD4.2 might represent novel genes. The best three cross combinations for the development of RIL populations were predicted to improve SD. The selected RILs and the identified QTLs might be applicable to improve the rice pre-harvest sprouting tolerance by the marker-assisted selection approach.

Effects of pre-harvest chemical application on rice desiccation and seed quality

“…Seed was germinated in a growth chamber at (30±1) °C for 10 d with a 12-h light/12-h dark photoperiod. They were considered to have germinated when the radical was longer than 2 mm Wang et al, 2014). The number of germinated seed was counted every day.…”

“…Weather conditions at harvest time are frequently unfavorable in subtropical and tropical regions. High temperature and humidity during harvest may cause rice seeds to sprout prematurely Wang et al, 2014). To solve this problem, the seeds should be harvested and dried as soon as possible before storage.…”

Identification of QTLs with Additive, Epistatic, and QTL × Seed Maturity Interaction Effects for Seed Vigor in Rice

“…In order to identify the dynamic characteristics of seed vigor during seed maturity stages, the vigor of seeds collected at 4, 5, and 6 weeks after heading was investigated in this study, because the time from heading to harvest is about 4-6 weeks in Nanjing (Jiangsu Province, China; 118°50′ E, 32°02′ N) Wang et al 2014). In the evaluation of seed vigor, the germination speed might be more important than the final germination rate, since the former usually decreases more quickly than the latter during seed storage (Hayashi et al 2008).…”

“…Filed managements were carried out according to the local standard methods . The main panicles of each line were harvested at the early (4 weeks after heading), middle (5 weeks after heading), and late (6 weeks after heading) maturity stages according to Wang et al (2014). The harvested seeds were dried at 42°C for 7 days to a~13.5 % seed moisture content then stored in room temperature (~25°C) for 3 months to break seed dormancy.…”

“…QTL analysis can be adapted to include the effects of developmental stages (Zhu 1995;Wu and Lin 2006). In rice, the dynamic QTL analysis has been used to dissect the genetic control of several quantitative traits during seed developmental stages such as grain filling (Takai et al 2005) and seed dormancy Wang et al 2014). Epistasis, an additive-by-additive interaction between QTLs, has been recognized as contributing to the genetic control of quantitative traits such as seed reserve utilization, salt tolerance, and seed dormancy (Wang et al 2012Cheng et al 2013Cheng et al , 2014.…”