Genetic dissection of ear-related traits using immortalized F2 population in maize

Ear-related traits are often selection targets for maize improvement. This study used an immortalized F(IF) population to elucidate the genetic basis of ear-related traits. Twelve ear-related traits(namely, row number(RN), kernel number per row(KNPR), ear length(EL), ear diameter(ED), ten-kernel thickness(TKT), ear weight(EW), cob diameter(CD),kernel length(KL), kernel width(KW), grain weight per ear(GW), 100-kernel weight(HKW), and grain yield per plot(GY)),were collected from the IFpopulation. The ear-related traits were comprised of 265 crosses derived from 516 individuals of the recombinant inbred lines(RILs) under two separated environments in 2017 and 2018, respectively. Quantitative trait loci(QTLs) analyses identified 165 ear traits related QTLs, which explained phenotypic variation ranging from 0.1 to 12.66%. Among the 165 QTLs, 19 underlying nine ear-related traits(CD, ED, GY, RN, TKT, HKW, KL, GW, and KNPR)were identified across multiple environments and recognized as reliable QTLs. Furthermore, 44.85% of the total QTLs showed an overdominance effect, and 12.72% showed a dominance effect. Additionally, we found 35 genomic regions exhibiting pleiotropic effects across the whole maize genome, and 17 heterotic loci(HLs) for RN, EL, ED and EW were identified. The results provide insights into genetic components of ear-related traits and enhance the understanding of the genetic basis of heterosis in maize.

Performance and Inheritance of Rice Starch RVA Profile Characteristics

The classification and inheritance of rice starch RVA profiles were studied by testing RVA profiles of F2 clonally propagated population and some varieties, including japonica, indica, and glutinous types. All the RVA profiles of accessions could be divided into six kinds based on the cluster analysis, that is A, B, C, D, E and F. Feature profile of sticky variety was type A. The profiles of indica varieties could be presented as B, C, D, E and F types and that of japonica varieties fell into D, E and F types.RVA profiles of the rice were mainly affected by apparent amylose content (AAC), but the difference of RVA profiles could also be detected in the varieties with similar AAC. The close relationship between RVA profile indices and sensory of low or middle AAC varieties suggested that the RVA profiles can be used as indirect index to evaluate eating and cooking quality. In four hybrid combinations, the component indices of RVA profiles of F1 were between those of its parents except peak viscosity and pasting temperature. Also, in F2 clonally propagated population, all the components of the RVA profiles showed continuous segregation,suggesting that all of them were controlled by a series of minor genes, although Wx gene may play an important role in determining the RVA profiles. These results may provide some new information useful for rice quality breeding program.

Identification of QTL for Popping Characteristics Using a BC_2F_2 Population and Comparison with Its F_(2:3) Population in Popcorn

Normal corn germplasm can be used to improve popcorn （Zea mays L.） through 1-2 backcrosses with popcorn as recurrent parents. Popping characteristics of derived lines from popcorn × dent or flint corn crosses play a determinant role in popcorn breeding. Advanced backcross QTL methods can effectively combine QTL identification and plant breeding. 220 selected BC2F2 families developed from a cross between Dan 232, a dent corn inbred line, and N04, an elite popcorn inbred line, were evaluated for three popping characteristics, popping volume, flake size, and popping rate, under two environmental conditions. Using composite interval mapping, a total of 10 significant QTLs were detected, and of these, 2 to 4 QTLs were identified for each trait. Six QTLs had favorable alleles contributed by Dan 232. Comparison with the 15 QTLs detected in the F2：3 families showed that 3 QTLs were the same in both populations. The QTLs should be redetected in generations developed through severe selection. Improved N04 and near isogenic lines could be developed from this BC2F2 population through selfing or another 1 to 2 backcrosses with N04.

Mapping of QTL for Fiber Length Using Interspecific Gossypium hirsutum × G.barbadense F_2 Population

Cotton occupies a pre-eminent place among cash crops as it guides the destiny of a large section of the farming community as well as that of a flourishing textile industry.As the yarn manufacturing industry has undergone a technological revolution,more emphasis is given to quality of the raw

Application of soybean shoot-cutting in SMV-resistance genetic analysis

Soybean mosaic virus （SMV） is one of the most serious diseases affecting soy-bean yield. Recombination inbred lines （RILs） are common materials for resistance genetic research. However, the population construction always takes quite a long time which pro-long the breading process. Shoot-cutting is a well-established technique for plant multipli-cation. It has high successful ratio in soybean. In this study, we use shoot-cutting to multiply two F2 populations from the crosses of susceptible and resistant varieties. Soybean plants can be multiplied from 1 into 3 homogenous ones within 30 days, bringing on well-grown plants with normal seeds. The SMV resistance from cutting-shoot plants was consistent with that from original plants. When shoot-cutting is applied in a F2 population, the pheno-typic and genotypic data can be simultaneously collected and corresponding saved during population development. The genetic research and resistant breeding can be effectively promoted by this technology.