Expression of PIN Genes in Rice （Oryza sativa L.）： Tissue Specificity and Regulation by Hormones

Twelve genes of the PIN family in rice were analyzed for gene and protein structures and an evolutionary relationship with reported AtPINs in Arabidopsis. Four members of PIN1 （designated as OsPINla-d）, one gene paired with AtPIN2 （OsPIN2）, three members of PIN5 （OsPIN5a-c）, one gene paired with AtPIN8 （OsPIN8）, and three monocot-specific PINs （OsPIN9, OsPINIOa, and b） were identified from the phylogenetic analysis. Tissue-specific expression patterns of nine PIN genes among them were investigated using RT-PCR and GUS reporter. The wide variations in the expression domain in different tissues of the PIN genes were observed. In general, PIN genes are up-regulated by exogenous auxin, while different responses of different PIN genes to other hormones were found.     

Introgression of qPE9-1 allele, conferring the panicle erectness, leads to the decrease of grain yield per plant in japonica rice （Oryza sativa L.）

Panicle architecture is closely related to yield formation. The qPE9-1 gene has been proved to be widely used in high-yield rice cultivar developments, conferring erect panicle character in japonica rice. Recently, qPE9-1 has been successfully cloned; however, the genetic effect on grain yield per plant of the erect panicle allele qPE9-1 is controversial yet. In the present study, a drooping panicle parent Nongken 57, carrying qpe9-1 allele, was used as recurrent parent to successively backcross to a typical erect panicle line from the double haploid (DH) population (Wuyunjing 8/Nongken 57), which was previously shown to carry qPE9-1 allele. Thus a pair of near-isogenic lines (NILs) was developed. The comparison of agronomic traits between the NILs showed that, when qpe9-1 was replaced by qPE9-1, the panicle architecture was changed from drooping to erect; moreover, the panicle length, plant height, 1000-grain weight and the tillers were significantly decreased, consequently resulting in the dramatic decrease of grain yield per plant by 30%. Therefore, we concluded that the qPE9-1 was a major factor controlling panicle architecture, and qPE9-1 had pleiotropic nature, with negative effects on grain yield per plant. This result strongly suggests that the erect panicle allele qPE9-1 should be used together with other favorable genes in the high-yield breeding practice. In addition, the effect of qPE9-1 on eating and cooking quality was also discussed in the present study.