The introduction of genetically modified (GM) soybean into farming systems raises great concern that transgenes from GM soybean may flow to endemic wild soybean via pollen.  This may increase the weediness of transgenic soybean by increasing the fitness of hybrids under certain conditions and threaten the genetic diversity of wild soybean populations.  Although pollen-mediated gene flow between GM crops and wild relatives is dependent on many factors, the sexual compatibility (SC) determined by their genetic backgrounds is the conclusive factor.  The considerable genetic variation among wild soybean populations may cause compatibility differences between different wild and cultivated soybeans.  Thus, an evaluation of the SC between transgenic soybean and different wild soybeans is essential for assessing the environmental consequences of cultivated soybean–wild soybean transgene flow.  The podding and seed sets were assessed after artificial hybridization using transgenic glyphosate-resistant soybean as the paternal parent and 18 wild soybean populations as the maternal parents.  Then, the average number of filled seeds produced in 200 flowers (AFS) was calculated for each wild soybean under natural self-pollination as well as under artificial crossing with transgenic soybean.  Finally, the index of cross-SC was calculated (ICSC) as the ratio of the AFS of wild soybean artificially crossed with transgenic soybean and the AFS of naturally self-pollinated wild soybean.  The results demonstrated that after self-pollination and crossing with transgenic soybean, the average podding rates of 18 wild soybean populations ranged within 96.50–99.50% and 4.92–18.03%, and the average filled seed numbers per pod varied from 1.70 to 2.69 and 0.20 to 0.48, respectively.  The results showed that approximately 89% of wild soybeans displayed either medium or higher than medium SC with transgenic soybean (ICSC>1.0%).  This implied the high possibility of gene flow via pollen from transgenic soybean to wild soybean.

The panicle architecture and grain size of rice affect not only grain yield but also grain quality, especially grain appearance. The erect-panicle (EP) trait controlled by the qpe9-1/dep1 allele has been widely used in high-yielding japonica rice breeding, but usually accompanied with moderate appearance of milled rice. The null gs9 allele shows a good potential for improving grain shape and appearance. However, GS9 and qPE9-1/DEP1 loci are tightly linked, and their interaction is unclear, which obviously restricts their utilization in modern rice breeding. In the present study, comparative analyses of protein and mRNA levels revealed that GS9 and qPE9-1 function independently. Three near-isogenic lines (NILs) carrying various allelic combinations of these two loci, NIL (gs9/qpe9-1), NIL (GS9/qPE9-1) and NIL (gs9/qPE9-1), in the EP japonica cultivar 2661 (GS9/qpe9-1) background were developed for genetic interaction analysis. GS9 and qPE9-1 had additive effects on determining grain size, and the null gs9 allele could decrease grain chalkiness and improve grain appearance without affecting plant and panicle architecture in EP japonica cultivars. Additionally, introgression lines (ILs) developed in another released EP japonica cultivar Wuyujing 27 (WYJ27) background showed the same additive effect and the feasibility of utilizing the gs9 allele to improve grain appearance quality in high-yielding EP cultivars. This study provides an effective strategy for rice breeders to improve rice grain appearance in EP japonica and related cultivars.