Study On Identification And Evaluation Of Peanut Wild Species And Utilization Of Incompatible Wild Species

Cultivated varieties of peanut are the world’s major cash crop and an important source of high-quality edible oil and vegetable protein.With the development of the economy and the increasing standard of living of the people,higher requirements are being placed on the quality and resistance of peanut varieties.However,the genetic base of cultivated peanuts is narrow,and it is increasingly difficult to breed breakthrough varieties by relying solely on crosses within cultivated species.Peanut wild species contain a rich genetic diversity,with high quality,high yield,resistance and other excellent genes,especially outside the peanut zone group of unaffiliated wild species,resistance is stronger than the peanut zone group of affinity wild species.However,the unaffiliated wild species are crossed with cultivars,and the hybrid embryos are defeated and difficult to use by conventional means.For this reason,a systematic study was carried out to broaden the genetic base of peanut breeding using peanut unaffiliated wild species.The main results are as follows:1.To investigate the utilization value of wild species of peanut,wild species grown at two locations(Guangxi and Shandong)were analysed for quality testing and evaluation of late blotch and insect-infested leaf damage ratings.The results showed that five biochemical qualities,including protein,oil,oleic acid,unsaturated fatty acid and linolenic acid content,showed highly significant differences between locations and wild species material,and that there was significant intercropping between locations and wild species of peanut.A.correntina(A14)and A.duranensis(A17)were found to be high in protein,and A.correntina(A3)and A.paraguariensis(A24)were found to be high in oil at both locations.The wild species material was grown in Shandong and had significantly higher oil,unsaturated fatty acid and linolenic acid contents than in Guangxi.Most of the wild species investigated were highly resistant to late blotch disease and insect pests,with A.stenosperma(A16),A.duranensis(A17)and A.appresipilla(A25)being immune to both late blotch disease and insect pests.And in terms of insect pest resistance,the proportion of unaffiliated wild species with superior resistance was higher in their zonation than the proportion of affiliated wild species in the peanut zonation.2.To investigate the mechanism of distant hybrid incompatibility,endogenous hormone assays were performed on samples taken at three periods of embryonic development(flower base,pegs and pods)of the peanut incompatible hybrid combinations.The results showed that three growth hormones,ten cytokinins and three gibberellins were significantly down-regulated in the unaffiliated crosses compared to the control affine crosses,indicating that hormone imbalance did occur in the unaffiliated crosses.Based on the measured hormone levels,the hormone treatment solution formulation could be adjusted after in situ embryo rescue technique pollination.3.In situ embryo rescue technique was used to investigate the effect of improving the original hormone formulation(t ZR replacing BAP)to overcome the impediment of crossing unaffinity between peanut cultivars and unaffiliated wild species.The seeds harvested after the cross were identified by competitive allele specific PCR(KASP).32 true hybrids were identified from all five cross combinations and the modified hormone formulation was found to be superior to the original formulation.4.The results of the interspecific hybrid resistance survey of 30 unrelated crosses showed that 11 were moderately resistant to late blotch,11 showed no damage to insect pests and 12 showed high resistance.Two high protein,four high oil and 20 high oleic acid materials were obtained from the interspecific hybrids,which inherited the high oleic acid gene from Huayu 665 and the excellent insect pest resistance and high protein and oil genes of the unrelated wild species.Genetic diversity analysis of the four main types of cultivars,wild species and interspecific hybrids showed that wild species were the most genetically diverse,followed by interspecific hybrids,and cultivars the least.Analysis using Nei’s(1972)genetic distance and UPGMA method revealed that cultivated peanut pearl bean and multigranular types clustered together,and dragon raw and common types clustered together,with genetic diversity being pearl bean > common type > dragon raw >multigranular type.