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OsMADS1 plays crucial roles in the specification of floral organ identity and the determinacy of floral meristem in rice (Oryza sativa). Here we isolated a rice mutant cy15 with defective spikelets. Map-based cloning identified cy15 as a novel mutation in the C terminus of OsMADS1. Severe cy15 spikelets contained normal inner whorl organs but defective paleas, opposite to four abnormal whorls of Osmads1 flowers reported previously. In the cy15 spikelets, the size of the body was remarkably reduced in paleas, indicating a critical role of OsMADS1 in its differentiation. Moreover, the development of palea was impaired in the early stage of the cy15 spikelets. The sub-subcellular location of the mutant OsMADS1 was also affected in cy15. On the other hand, the truncated C terminus of the mutant OsMADS1 from cy15 still showed a significant transcriptional activator function. Meanwhile, though the mutant OsMADS1 retained intact M, I and K domains, its interactions with two highly homologous A-class proteins, OsMADS15 or OsMADS14, were weakened or abolished. Our data suggested that the C-terminal sequence of OsMADS1 might be required for maintaining normal morphology of spikelets in rice.

Verticillium wilt disease caused by soil-borne fungus Verticillium dahliae (V. dahliae), is a serious threats to cotton growth worldwide. Endogenous phytohormones, such as salicylic acid (SA), jasmonic acid (JA), ethylene (ET), and brassinosteroid (BR) have been reported to play important roles in defense response in plants. Based on highthroughput RNA sequencing analysis of resistant Gossypium hirsutum (G. hirsutum) variety Zhongzhimian KV-3, comparing the transcriptome with V. dahliae infection and non-infection, eight differentially expressed candidate genes functions indicated in SA (GhPUB17, GhTGA7 and GhPR1), JA (GhJAZ10 and GhbHLH18), ET (GhEBF1), cytokinine (GhE13L13) and BR (GhBZR1) signal pathways were investigated via virus-induced gene silencing (VIGS) using cotton leaf crumple virus (CLCrV) vector. The expression of eight genes was further validated through quantitative realtime PCR. The result showed that the expression level of GhPUB17, GhJAZ10, GhbHLH18, GhEBF1 and GhE13L13 increased faster in resistant variety Zhongzhimian KV-3 than in susceptible variety 86-1 upon V. dahliae infection. Silencing up-regulated genes GhPUB17, GhJAZ10, GhbHLH18 and GhEBF1 significantly enhanced resistant variety susceptibility to V. dahliae and silencing down-regulated genes GhTGA7 and GhBZR1 significantly increased susceptible variety resistance to V. dahliae. Taken together, these genes are important components in response to V. dahliae infection.

Lipoxygenases (LOXs) are enzymes involved in lipid peroxidation. Here we reported the identification, molecular and functional characterization of the gene encoding rice (Oryza sativa L.) seed LOX3 (sLOX3). Via a map-based cloning strategy we identified Os03g0700400 as the candidate gene encoding sLOX3. Further functional complementary test and biochemical characterization of the recombinant Os03g0700400 protein verified the identification. The sLOX3 gene was highly expressed in roots, moderately in embryos and very weakly in leaves, leaf sheaths and stems. Transient expression experiment (in rice protoplasts) and subsequent laser confocal microscopic analysis demonstrated that the sLOX3 protein was localized into the cytosol. We next showed that overexpression of sLOX3 in a japonica sLOX3-normal rice cultivar, Wuyunjing 7 accelerated the decrease of seed germination ability when the seeds were routinely stored, which demonstrated that sLOX3 had a negative effect on seed longevity (storability). Meanwhile, an increased occurrence of embryo decay was observed in the same transgenic seeds, suggesting that sLOX3 might negatively affect seed longevity by facilitating colonization of particular seed pathogens. Our result forwarded the understanding of the effects of 9-LOX on rice seed longevity.

Protein content (PC) and protein index (PI) play important roles in determining nutritional quality in rice (Oryza sativa L.). We used 71 lines derived from “Asominori/IR24” to analyze the developmental behavior of PC and PI through unconditional and conditional QTL mapping methods. In all, 10 unconditional QTLs and 6 conditional QTLs for PC, and 11 unconditional QTLs and 9 conditional QTLs for PI, were identified at four stages of grain filling. More were identified in the first three stages than at the final stage. Temporal patterns of gene expression for PC and PI differed over time, with several QTLs being expressed across two or three stages but many being expressed at only one stage. Some of these QTLs were closely linked with maturity QTLs reported previously. Many QTLs for PC and PI were co-localized, supporting the significant correlation found between PC and PI. Our results suggest that dynamic QTL mapping might be a valid means for revealing more genetic information about protein accumulations during seed development.