Li W.-X.,Zhejiang University |
Li W.-X.,Wuxi Qiushi Agri Biological Research Center |
Zhao H.-J.,Zhejiang University |
Zhao H.-J.,Wuxi Qiushi Agri Biological Research Center |
And 4 more authors.
Transgenic Research | Year: 2014
Phytic acid (PA) is poorly digested by humans and monogastric animals and negatively affects human/animal nutrition and the environment. Rice mutants with reduced PA content have been developed but are often associated with reduced seed weight and viability, lacking breeding value. In the present study, a new approach was explored to reduce seed PA while attaining competitive yield. The OsMRP5 gene, of which mutations are known to reduce seed PA as well as seed yield and viability, was down-regulated specifically in rice seeds by using an artificial microRNA driven by the rice seed specific promoter Ole18. Seed PA contents were reduced by 35.8-71.9 % in brown rice grains of transgenic plants compared to their respective null plants (non-transgenic plants derived from the same event). No consistent significant differences of plant height or number of tillers per plant were observed, but significantly lower seed weights (up to 17.8 % reduction) were detected in all transgenic lines compared to null plants, accompanied by reductions of seed germination and seedling emergence. It was observed that the silencing of the OsMRP5 gene increased the inorganic P (Pi) levels (up to 7.5 times) in amounts more than the reduction of PA-P in brown rice. This indicates a reduction in P content in other cellular compounds, such as lipids and nucleic acids, which may affect overall seed development. Put together, the present study demonstrated that seed specific silencing of OsMRP5 could significantly reduce the PA content and increase Pi levels in seeds; however, it also significantly lowers seed weight in rice. Discussions were made regarding future directions towards producing agronomically competitive and nutritionally valuable low PA rice. © 2014 Springer International Publishing Switzerland.
Zhang H.-L.,Zhejiang University |
Zhang H.-L.,Wuxi Qiushi Agri Biological Research Center |
Huang J.-Z.,Zhejiang University |
Liu Q.-L.,Zhejiang Academy of Agricultural Sciences |
And 8 more authors.
Molecular Breeding | Year: 2014
The two-line hybrid system in rice is becoming more important and employs environment-conditioned genic male sterile (EGMS) lines sensitive to photoperiod (photoperiod-sensitive genic male sterile), temperature [temperature genic male sterile (TGMS)], or a combination of the two (photoperiod temperature genic male sterile). At least 18 EGMS genes have been mapped, and two cloned, but controversies exist. For example, three different genes were reported to underlie the TGMS trait in three independently identified progenitors, Annong S-1, Zhu 1S, and Guangzhan 63S, while another study demonstrated that the TGMS genes in Annong S-1 and Zhu 1S are allelic. In the present study, we confirmed the allelism of the three TGMS genes, which means there is a common TGMS gene(s) in these lines. Knowing there is an association between the mutant allele (RNZm) of a ribonuclease gene (RNZ) with the TGMS trait in Guangzhuan 63S, we then sequenced RNZ for 14 commercial EGMS and 21 non-EGMS lines, and we developed two derived cleaved amplified polymorphic sequence (dCAPS) markers to detect RNZm alleles in 32 EGMS and 310 non-EGMS lines. The analyses showed that the RNZm allele existed exclusively in EGMS lines; all non-EGMS lines contained the functional RNZgc or RNZtc allele. Furthermore, two segregating populations that included 2,429 individuals were developed by crossing Zhu 1S (RNZm) to two non-EGMS lines (both with RNZtc); examination of the segregation of male sterile and fertile plants indicated that the TGMS trait was under the control of a single gene; analysis of the markers revealed the RNZm allele exclusively in TGMS plants and the RNZtc allele only in non-TGMS plants in both populations. The dCAPS markers could therefore help select TGMS progeny in breeding programs, which will save time and labor, and improve breeding efficiency and accuracy. © 2014 Springer Science+Business Media Dordrecht.