GROWTH-REGULATING FACTOR (GRF) genes encode plant-specific transcription factors and play critical roles in regulating the growth and development of lateral organs. In order to explore the agricultural potential of Brassica rapa GRF genes (BrGRFs), we constructed two BrGRF-overexpressing B. napus plants (BrGRF3-1OX and -9OX). BrGRF3-1OX and -9OX developed larger cotyledons, leaves, and seeds than the wild type. The increased organs’ sizes were due to increases in cell number, but not due to cell size alterations. RT-PCR analysis revealed that BrGRFs regulated the expression of a wide range of genes that are involved in gibberellin-, auxin-, cell division-related growth processes. Taken together, our data indicate that BrGRFs act as positive regulators of B. napus growth, thus raising the possibility that they may serve as a useful genetic source for crop improvement with respect to organ size and seed production.

Gayabyeo, a Tongil-type rice variety, has been known to be resistant to the brown planthopper (BPH) in Korea. For genetic analysis of BPH resistance of Gayabyeo, we developed an F2 and F3 population derived from a cross between Gayabyeo and Taebaegbyeo which is a Tongil-type BPH susceptible rice variety. Based on the previously detected 284,501 putative SNPs between Gayabyeo and Taebaegbyeo, 99 cleaved amplified polymorphic sequences (CAPS) markers were developed, and they have been used for genotyping 180 F2 plants. By comparison of resequencing data of Gayabyeo and the sequences of already reported BPH resistance genes (Bph3, BPH9, Bph14, BPH18, BPH26), it was revealed that Gayabyeo has Bph3 and BPH26 resistance genes. Two InDel markers, Bph3IND and BPH26IND, were developed, which can be used as selection markers in breeding program aiming at introducing BPH resistance genes of Gayabyeo into Korean high quality japonica rice varieties. In addition, BPH bioassay was performed with 180 F3 lines for BPH resistance QTL analysis. Two major QTLs were found on chromosome 4 and 12. The regions of these two QTLs included Bph3 and BPH26, which also supported that Gayabyeo has Bph3 and BPH26 resistance genes. These results would be useful in accelerating development of various BPH-resistant high quality japonica rice varieties in Korea.