Effect of Temperature on Pollen Fertility in Inter-Subspecific Rice Hybrids

Seventeen rice varieties and hybrids of different types (indica, japonica, javanica, indica hybrid, japonica hybrid and inter-subspecific hybrid) were evaluated to determine the effect of temperature on pollen fertility in inter-subspecfic hybrids. The pollen fertility of inter-subspecific hybrids was greatly reduced when average daily temperature dropped to 22.0 - 23.0℃ at meiosis stage, and the extent of pollen fertility reduction varied greatly with respect to different hybrids. However, the pollen fertility reduction of indica and japonica hybrids and conventional varieties was not obvious under the same regime of temperature conditions. When the average daily temperature dropped to 20℃, the pollen development of conventional varieties and hybrids was also affected. Correlation analysis revealed that there existed a positive correlation between pollen fertility and average daily temperature. A significant difference (P<0.01) was also found between the two correlation coefficients i.e. inter-subspecific hybrids and conventional varieties. Temperature at meiosis stage of pollen mother cell was a key factor in pollen developing, and the pollen fertility of inter-subspecific hybrids was more sensitive to low temperature than that of traditional variety.

Effect of day length and temperature on the pollen fertility in photo(thermo)-sensitive genic male-sterile rice

The effect of day length and temperature on the pollen fertility of five photoperiod-sensitive genic male-sterile japonica rice lines (PGMSR) and three temperature-sensitive genic malesterile indica rice lines (TGMSR) were investigated in phytotron. The light source used for illumination was xenon lamp, and the light intensity which plant accepted on the leaf surface was 300—350μmol photons ms. The results indicated that pollens of PGMSR 7001S and E47S aborted completely whereas a little part of 31116S pollens appeared normal under long day photoperiod (LD,25℃,15h) (Table 1). High temperature (HT, 30℃, 12h) and lower temperature (LT,

A Novel C2-Domain Phospholipid-Binding Protein, OsPBP1, Is Required for Pollen Fertility in Rice

Pollen fertility is a crucial factor for successful pollination and essential for seed formation. Recent studies have suggested that a diverse range of internal and external factors, signaling components and their related pathways are likely involved in pollen fertility. Here, we report a single C2-domain containing protein, OsPBP1, initially identified through cDNA microarray analysis. OsPBP1 is a single copy gene and preferentially expressed in pistil and pollen but downregulated by pollination. OsPBP1 had a calcium concentration-dependent phospholipid-binding activity and was localized mainly in cytoplasm and nucleus, but translocated onto the plasma membrane in response to an intracellular Ca^2＋ increase. Pollen grains of antisense OsPBP1 transgenic lines were largely nonviable, germinated poorly in vitro and of low fertility. OsPBP1 protein was localized in a region peripheral to pollen wall and vesicles of elongating pollen tube, and its repressed expression reduced substantially this association and led to alteration of microfilament polymerization during pollen germination. Taken together, these results indicate that OsPBP1 is a novel functional C2-domain phospholipids-binding protein that is required for pollen fertility likely by regulating Ca^2＋ and phospholipid signaling pathways.

Less and shrunken pollen 1(LSP1) encodes a member of the ABC transporter family required for pollen wall development in rice(Oryza sativa L.)

Pollen fertility is an agronomic trait that strongly influences rice yield. Recent studies have revealed that the development of the pollen wall is required for pollen fertility and is regulated by several genes. However, the mechanisms underlying pollen and pollen wall development in rice remain largely unknown. In the present study, a point mutation in a gene on chromosome 1 was identified that resulted in the production of less and shrunken pollen(LSP) and led to defects in pollen wall formation. This gene was named LSP1 and was found to encode a member of the adenosine triphosphate-binding cassette(ABC)transporter G subfamily, OsABCG3. Two other loss-of-function mutants of LSP1/OsABCG3,generated using CRISPR/Cas9 technology, showed the same male sterile phenotype. The LSP1/OsABCG3 gene showed a spatio-temporal expression pattern in the developing anthers, and is an ortholog of the Arabidopsis genes At ABCG1 and At ABCG16, which play an important role in pollen wall development. Mutation of LSP1/OsABCG3 affected the expression of several genes involved in pollen and pollen wall formation. These results suggest that LSP1/OsABCG3 is critical for normal pollen fertility and shed light on the molecular mechanisms underlying rice pollen wall development.

Perennial aneuploidy as a potential material for gene introgression between maize and Zea perennis

Hybridization,which allows for gene flow between crops,is difficult between maize and Zea perennis.In this study,we aim to initiate and study gene flow between maize and Z.perennis via a special aneuploid plant（MDT） derived from an interspecific hybrid of the two species.The chromosome constitution and morphological characters of MDT as well as certain backcross progenies were examined.Results from genomic in situ hybridization（GISH） indicate that aneuploid MDT consisted of nine maize chromosomes and 30 Z.perennis chromosomes.The backcross progenies of MDTxmaize displayed significant diversity of vegetative and ear morphology;several unusual plants with specific chromosome constitution were founded in its progenies.Some special perennial progeny with several maize chromosomes were obtained by backcrossing MDT with Z.perennis,and the first whole chromosome introgression from maize to Z.perennis was detected in this study.With this novel material and method,a number of maize-tetraploid teosinte addition or substitution lines can be generated for further study,which has great significance to maize and Z.perennis genetic research,especially for promoting introgression and transferring desirable traits.

Characterization of a novel DUF1618 gene family in rice

Domain of unknown function （DUF） proteins represent a number of gene families that encode functionally uncharacterized proteins in eukaryotes. For example, DUF1618 family members in plants possess a 56-199-amino acid conserved domain and this family has not been described previously. Here, we report the characterization of 121 DUF1618 genes identified in the rice genome. Based on phylogenetic analysis, the rice DUF1618 family was divided into two major groups, each group consisting of two clades. Most DUF1618 genes with close phylogenetic relationships are located in gene clusters on the chromosomes, indicating that gene duplications increased the number of DUF1618 genes. A search for DUF1618 genes in genomic and/or expressed sequence tag databases for 35 other plant species showed that DUF1618 genes are only present in several monocot plants, suggesting that DUF1618 is a new gene family that originated after the dicot-monocot divergence. Based on public microarray databases, most rice DUF1618 genes are expressed at relatively low levels. Further experimental analysis showed that the transcriptional levels of some DUF1618 genes varied in different cultivars, and some responded to stress and hormone conditions, suggesting their important roles for development and fitness in rice （Oryza sativa L.）.