Polygenic Heritability of Rose Root Rot Disease Resistance in Offspring of Rosa multiflora

Rose root rot disease caused by Pythium helicoides Drechsler has brought heavy damage to cut rose production in Japan,and it has became apparent that Rosa multiflora showed resistance to this disease.Roses have been bred by interspecies crossing with Rosa species including of R.multiflora,and many progenies of R.multiflora have been bred as determined cluster-flowered roses.However,the genetic architecture of this resistance remains.So,in this study,four kinds of R.multiflora and 21 rose cultivars that have been clarified in the cross-fertilization genealogy with R.multiflora were used as plant materials,and the inheritability of resistance to root rot disease was investigated.Four kinds of R.multiflora had all high resistance,and the resistance to root rot disease in R.multiflora was inherent characteristic of species.Five varieties not less than 50% in relatedness with R.multiflora were shown as varied ‘resistant’ and ‘moderately resistant’.Therefore,the inherent resistant characteristic in R.multiflora was not controlled by single major gene,and the resistibility in R.multiflora was not cytoplasmic but nuclear heredity.Although there was significant negative relation between relative root rot severity and relatedness with R.multiflora,the variance of relative root rot severity had tendency to expand as relatedness with R.multiflora reduced.This result,therefore,indicated that the contingency of resistance expression increased as the relatedness with R.multiflora was reduced.The varieties having low degree of relatedness with R.multiflora had similar relative root rot severity with R.multiflora.These results indicated that we would be able to select resistant roses from progenies crossed with R.multiflora.

Food legume production in China

Food legumes comprise all legumes grown for human food in China as either dry grains or vegetables,except for soybean and groundnut.China has a vast territory with complex ecological conditions.Rotation,intercropping,and mixed cropping involving pulses are normal cropping systems in China.Whether indigenous or introduced crops,pulses have played an important role in Chinese cropping systems and made an important contribution to food resources for humans since ancient times.The six major food legume species(pea,faba bean,common bean,mung bean,adzuki bean,and cowpea) are the most well-known pulses in China,as well as those with more local distributions;runner bean,lima bean,chickpea,lentil,grass pea,lupine,rice bean,black gram,hyacinth bean,pigeon pea,velvet bean,winged bean,guar bean,sword bean,and jack bean.China has remained the world's leading producer of peas,faba beans,mung beans,and adzuki beans in recent decades,as documented by FAO statistics and China Agriculture Statistical Reports.The demand for food legumes as a healthy food will markedly increase with the improvement of living standards in China.Since China officially joined the World Trade Organization(WTO) in2001,imports of pea from Canada and Australia have rapidly increased,resulting in reduced prices for dry pea and other food legumes.With reduced profits for food legume crops,their sowing area and total production has decreased within China.At the same time,the rising consumer demand for vegetable food legumes as a healthy food has led to attractive market prices and sharp production increases in China.Vegetable food legumes have reduced growing duration and enable flexibility in cropping systems.In the future,production of dry food legumes will range from stable to slowly decreasing,while production of vegetable food legumes will continue to increase.