Mapping quantitative trait loci and predicting candidate genes for leaf angle in maize

Leaf angle of maize is a fundamental determinant of plant architecture and an important trait influencing photosynthetic efficiency and crop yields. To broaden our understanding of the genetic mechanisms of leaf angle formation, we constructed a F3:4 recombinant inbred lines (RIL) population to map QTL for leaf angle. The RIL was derived from a cross between a model inbred line (B73) with expanded leaf architecture and an elite inbred line (Zheng58) with compact leaf architecture. A sum of eight QTL were detected on chromosome 1, 2, 3, 4 and 8. Single QTL explained 4.3 to 14.2% of the leaf angle variance. Additionally, some important QTL were confirmed through a heterogeneous inbred family (HIF) approach. Furthermore, twenty-four candidate genes for leaf angle were predicted through whole-genome re-sequencing and expression analysis in qLA02-01and qLA08-01 regions. These results will be helpful to elucidate the genetic mechanism of leaf angle formation in maize and benefit to clone the favorable allele for leaf angle. Besides, this will be helpful to develop the novel maize varieties with ideal plant architecture through marker-assisted selection.

Mapping quantitative trait loci and predicting candidate genes for leaf angle in maize

ABSTRACTLeaf angle of maize is a fundamental determinant of plant architecture and an important trait influencing photosynthetic efficiency and crop yields. To broaden our understanding of the genetic mechanisms of leaf angle formation, we constructed an F3:4 recombinant inbred lines (RIL) population derived from a cross between a model inbred line (B73) with expanded leaf architecture and an elite inbred line (Zheng58) with compact leaf architecture to map QTL for leaf angle. A sum of 8 QTL were detected on chromosome 1, 2, 3, 4 and 8. Single QTL explained 4.3 to 14.2% of the leaf angle variance. Additionally, some important QTL were confirmed through a heterogeneous inbred family(HIF) approach. Furthermore, twenty-four candidate genes for leaf angle were predicted through whole-genome resequencing and expression analysis in qLA02-01and qLA08-01 regions. These results will be helpful to elucidate the genetic mechanism of leaf angle formation in maize and benefit to clone the favorable allele for leaf angle or develop the novel maize varieties with ideal plant architecture through marker-assisted selection.

Evaluation of the resistance of the breeding material beetroot to Cercospora amid epiphytoty in greenhouses the Moscow region

Relevance. An important feature that determines the technological qualities of varieties and hybrids of beetroot is an erect, compact leaf rosette that persists until the end of the vegetation of plants. In this regard, much attention is paid to the selection of resistance to diseases affecting the leaves of plants, including Cercospora beticola Sacc. When creating resistant to Cercospora interline hybrids based on CMS, the selection of parent components plays an important role. In agroclimatic conditions of the Moscow region, Cercospora on industrial beetroot rarely reaches an economically significant threshold of harmfulness. However, in 2019, epiphytic development of Cercospora on summer first-year crops was observed in the block film greenhouse of the «Federal Scientific Vegetable Center», which allowed to assess the promising breeding material.Material and method. Phytomonitoring on beetroot plantings and sowing of the experimental production Department of the «Federal Scientific Vegetable Center» growing was carried out by methods of visual diagnostics and microscopy. Cercospora lesion in the breeding nursery was evaluated on an 11-point scale, the ranking of samples into five groups of resistance - according to the degree of disease development (R%). Analyzed: 28 sterile lines (А); 13 fertile lines of fixers (В); 25 lines of pollinators (С) and 38 hybrid F1 (АхВхС).Results. It was found that more than half of the studied lines were receptive to Cercospora. The share of relatively resistant lines was 13%. Most of them (8%) are ms - lines « obtained by pollination of CMS with mf-lines В. A close relationship (r=0.86-0.89) between the index of lesion of fixators and the degree of disease development of ms- lines was revealed, in some simple combinations a positive effect of heterosis on resistance to Cercospora relative to mf-В was noted. In the submitted sample F1 hybrids mainly observed between the nature of inheritance according to the degree of disease development (R, %), mixed effects the base line stability of pollinator mf-С (r=0,32) and a closer correlation of the stability of hybrid offspring the F1 with the resistant parent ms-line А (r=0.55). As a result of the evaluation, the most resistant to Cercospora ms- and mf-lines and derived from them hybrid F1, among which only 9% were included in the group of relatively resistant to C. beticola.

Results and prospects of European radish breeding

Relevance Currently, the first place goes to the creation of new high-yielding varieties and hybrids F1 crops that meet the requirements of modern industrial technologies. Heterosis hybrids have high yield, marketability, equalization, friendly yield and resistance to disease. Methods When developing new varieties and hybrids of radish suitable for mechanized harvesting, attention should be paid to the strength of the attachment of the leaf outlet and its upright position, the uniformity of immersion in the soil and the easy pull-out of root crops. Studies were performed in a protected (heated film greenhouse) and open ground in All-Russian Scientific Research Institute of Vegetable Growing – Branch of the FSBSI Federal Scientific Vegetable Center. Results The results of breeding work with European radish are presented. According to the results of expert evaluation, the state register of breeding achievements included two varieties of European summer radish – Bianca, Sirius and one hybrid of European winter radish – Tsyganskiy Baron F1. The new varieties are distinguished by uniformity in shape, length, diameter of the root crop, compact leaf rosette, form a root crop in a short and long daylight, recommended for cultivation under film shelters and in the open ground (early spring and summer sowing time). As a result of repeated inbreeding, inbred lines of European winter radish (brought to the seventh generation) were created, characterized by high equalization of the root crop, with strict self-compatibility. These lines were included in the process of creating heterosis hybrids. Evaluation of the obtained hybrids was carried out in the open ground. A hybrid of radish European winter Tsyganskiy Baron F1 – medium-ripe, flat-rounded root, black, weighing 220-260 g. Perspective hybrid in relation to the standard has a more aligned form of the root, with a rich black color and smooth surface. Tsyganskiy Baron F1 on the above indicators exceeds the standard night, resistant to stressful conditions.

Бьянка – новый сорт редьки

Выведен и испытан в Московской области новый перспективный сорт редьки европейской летней Бьянка для защищенного и открытого грунта. Отбор проводили по признаку устойчивости к цветушности, высокой товарности и урожайности, однородности по форме корнеплода. Описаны хозяйственно ценные признаки. Сорт пригоден для ранневесенних и летних посевов, скороспелый (от полных всходов до начала хозяйственной годности – 35–40 суток), с компактной листовой розеткой. Формирует корнеплод в условиях короткого и длинного светового дня. Устойчив к преждевременному цветению. Средняя масса корнеплода 45 г, урожайность 4,2–4,5 кг/м2.A new promising cultivar of European summer Bianca radish for protected and open ground has been bred and tested in the Moscow region. The breeding was performed for traits of sustainability to boltering, high yield and marketability, uniformity in the shape of the root. The economically valuable signs are described. The variety is suitable for early spring and summer crops, early ripening (from full germination to the beginning of economic validity – 35–40 days), with a compact leaf outlet. It forms the root crop in conditions of short and long daylight hours. Resistant to premature flowering. The average weight of the root 45 g, yield 4,2–4,5 kg/m2.